Title of Invention

A FUEL CELL SYSTEM FOR PRODUCING ELECTRICAL ENERGY

Abstract Described herein are fuel cell systems (10, 400, 420, 420, 460) and methods of using fuel cell systems. The systems include a fuel cell (20) that generates electrical energy using hydrogen and a fuel processor (15) that produces hydrogen from a fuel source (16). The fuel processor (15) includes a reformer (32) and a burner (30) that heats the reformer (32). One heat efficient fuel cell system described herein heats internal portions of a fuel cell (20) using a heating medium from a fuel processor (15). The heating medium may comprise gases exhausted at high temperatures from the fuel processor (15), which are then transported to the fuel cell (20). The heating medium may also include a gas that reacts catalytically in the fuel cell (20) to produce heat. Systems and methods for expediting fuel cell system start up are provided. Methods for shutting down a fuel cell system are also described that reduce the amount of moisture and gases in the reformer (32) and in one or more fuel cell components. One hydrogen efficient fuel cell system described herein transports hydrogen to an inlet of a burner (30). The hydrogen may comprise unused hydrogen from a fuel cell (20) and/or hydrogen produced in a reformer (32). The burner (30) comprises a catalyst that facilitates production of heat in the presence of the hydrogen.
Full Text
A FUEL CELL SYSTEM FOR PRODUCING ELECTRICAL ENERGY
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cellsystem for producing elctricaal
energy and generally to fuel cell technology. In particular, the invention relates to
systems for improving fuel cell system efficiency.
A fuel cell electrochemically combines hydrogen and oxygen to produce
electrical energy. The ambient air readily supplies oxygen. Hydrogen provision,
however, calls for a working supply. Gaseous hydrogen has a low energy density that
reduces its practicality as a portable fuel. Liquid hydrogen, which has a suitable
energy density, must be stored at extremely low temperatures and high pressures,
making storing and transporting liquid hydrogen burdensome.
A reformed hydrogen supply processes a fuel source to produce hydrogen.
The fuel source acts as a hydrogen carrier. Currently available hydrocarbon fuel
sources include methanol, ethanol, gasoline, propane and natural gas. Liquid
hydrocarbon fuel sources offer high energy densities and the ability to be readily
stored and transported. A fuel processor reforms the hydrocarbon fuel source to
produce hydrogen.
Fuel cell evolution so far has concentrated on large-scale applications such as
industrial size generators for electrical power back-up. Consumer electronics devices
and other portable electrical power applications currently rely on lithium ion and
similar battery technologies. Fuel cell systems that generate electrical energy for
portable applications such as electronics would be desirable but are not yet
commercially available. In addition, techniques that increase fuel cell system
efficiency would be beneficial.
SUMMARY OF THE INVENTION
The present invention relates to fuel cell systems and methods of using fuel
cell systems. The systems include a fuel cell mat generates electrical energy using
hydrogen and a fuel processor that produces hydrogen from a fuel source. The fuel
processor includes a reformer and a burner that heats the reformer.

A heat efficient fuel cell system described herein heats internal portions of a
fuel cell using a heating medium from a fuel processor. The heating medium may
comprise gases exhausted at high temperatures from the fuel processor, which are
then transported to the fuel cell. The heating medium may also include a gas that
reacts catalytically in the fuel cell to produce heat. When the gases include methanol
for example, a catalyst in the fuel cell facilitates production of heat using the
methanol. Similarly, a catalyst in the fuel cell may be employed to facilitate heat
production using hydrogen output from the reformer and provided to the fuel cell.
Heating a fuel cell in this manner allows fuel cell operating temperatures to be
reached sooner during fuel cell warm-up periods, and permits elevated operating
temperatures to be maintained when electrical energy is not being generated by the
fuel cell.
Systems and methods for expediting fuel cell system start up are provided.
The systems use electrical heat to expedite start up time before operating
temperatures are reached.
Methods for shutting down a fuel cell system are also described that reduce
the amount of moisture and gases in the reformer and in one or more fuel cell
components at shut down.
One hydrogen efficient fuel cell system described herein transports hydrogen
to an inlet of a burner. The hydrogen may comprise unused hydrogen from a fuel cell
and/or hydrogen produced in a reformer. The burner comprises a catalyst that
facilitates production of heat in the presence of the hydrogen.
In one aspect, the present invention relates to a fuel cell system for producing
electrical energy. The fuel cell system comprises a fuel processor and a fuel cell. The
fuel processor includes a reformer configured to receive a fuel source, configured to
output hydrogen, and including a catalyst that facilitates the production of hydrogen.
The fuel processor also includes a burner configured to provide heat to the reformer.
The fuel cell comprises a fuel cell stack configured to produce electrical energy using
hydrogen output by the fuel processor. The fuel cell also comprises a heat transfer
appendage that a) includes a portion arranged external to the fuel cell stack and b) is
in conductive thermal communication with an internal portion of the fuel cell stack.

The fuel cell system also comprises plumbing configured to transport a heating
medium from the fuel processor to the fuel cell.
In another aspect, the present invention relates to a method for generating
electrical energy in a fuel cell that receives hydrogen from a fuel processor. The fuel
processor is configured to process a fuel source to produce the hydrogen. The method
comprises providing the fuel source to the fuel processor. The method also comprises
transporting a heating medium from the fuel processor to the fuel cell when electrical
energy output by the fuel cell includes less than an electrical threshold or when
temperature of a component in the fuel cell is less than a temperature threshold. The
method further comprises heating a portion of the fuel cell. The method additionally
comprises transporting hydrogen from the fuel processor to the fuel cell. The method
also comprises detecting temperature of the component or electrical output of the fuel
cell. The method further comprises generating electrical energy in the fuel cell when
the temperature of the component is about equal to or greater than the threshold
temperature or when electrical energy output by the fuel cell is about equal to or
greater than an electrical threshold.
In yet another aspect, the present invention relates to a method for shutting
down a fuel cell system comprising a fuel cell that received hydrogen from a fuel
processor. The fuel processor includes a reformer and a burner that provided heat to
the reformer. The method comprises stopping electrical energy generation in the fuel
cell. The method also comprises discontinuing a supply of a fuel source to the
reformer, which is configured to receive the fuel source and output hydrogen. The
method further comprises generating heat in the burner to heat to the reformer after
discontinuing the supply of the fuel source to the reformer. The method additionally
comprises discontinuing heat generation in the burner. The method also comprises
flushing the burner with air.
In still another aspect, the present invention relates to a fuel cell system for
producing electrical energy. The fuel cell system comprises a fuel processor and a
burner. The fuel processor includes a reformer configured to receive a fuel source,
configured to output hydrogen, and including a catalyst that facilitates the production
of hydrogen. The fuel processor also includes a burner configured to provide heat to
the reformer. The fuel cell is configured to receive hydrogen produced in the reformer

and configured to produce electrical energy using the hydrogen. The fuel cell system
also comprises plumbing configured to transport hydrogen to the burner.
In another aspect, the present invention relates to a fuel cell system for
producing electrical energy. The fuel cell system comprises a fuel processor and a
burner. The fuel processor includes a reformer configured to receive a fuel source,
configured to output hydrogen, and including a catalyst that facilitates the production
of hydrogen. The fuel processor also includes a burner configured to provide heat to
the reformer. The fuel cell is configured to receive hydrogen produced in the reformer
and configured to produce electrical energy using the hydrogen. The fuel cell system
also comprises plumbing configured to transport oxygen from the fuel cell to the fuel
processor.
In yet another aspect, the present invention relates to a method for starting up
a fuel processor including a reformer and a burner that provides heat to the reformer.
The method comprises generating heat using an electrical heater that is configured to
heat the burner or a fuel source provided to the burner. The method also comprises
supplying the fuel source to the burner. The method further comprises catalytically
generating heat in the burner to heat the reformer. The method additionally comprises
supplying the fuel source to the reformer. The method also comprises generating
hydrogen in the reformer.
In still another aspect, the present invention relates to a system for heating a
fuel source before catalytic heat generation within a burner included in a fuel
processor. The system comprises a reformer configured to receive the fuel source,
configured to output hydrogen, and including a catalyst that facilitates the production
of hydrogen. The system also comprises a burner configured to provide heat to the
reformer. The system comprises an electric heater configured to heat the burner or the
fuel source provided to the burner.
In another aspect, the present invention relates to a fuel cell system for
producing electrical energy. The fuel cell system comprises a fuel processor. The fuel
processor includes a reformer configured to receive a fuel source, configured to
output hydrogen, and including a catalyst that facilitates the production of hydrogen.
The fuel processor also includes a burner configured to provide heat to the reformer.
The fuel cell comprises a fuel cell stack configured to produce electrical energy using

hydrogen output by the fuel processor. The fuel cell also comprises a heat transfer
appendage that a) includes a portion arranged external to the fuel cell stack and b) is
in conductive thermal communication with an internal portion of the fuel cell stack.
The fuel cell system also comprises plumbing configured to transport a heating
medium or a cooling medium between the fuel processor and the fuel cell.
In still another aspect, the present invention relates to a fuel cell system for
producing electrical energy. The fuel cell system comprises a fuel processor. The fuel
processor includes a reformer configured to receive a fuel source, configured to
output hydrogen, and including a catalyst that facilitates the production of hydrogen.
The fuel processor also includes a burner configured to provide heat to the reformer.
The fuel cell comprises a fuel cell stack configured to produce electrical energy using
hydrogen output by the fuel processor. The fuel cell also comprises a heat transfer
appendage that a) includes a portion arranged external to the fuel cell stack and b) is
in conductive thermal communication with an internal portion of the fuel cell stack.
The fuel cell system also comprises control logic configured to regulate heat transfer
or temperature for one or more components within the fuel cell system.
Accordingly, the present invention provides a fuel cell system for producing
electrical energy, the fuel cell system comprising: a fuel processor that comprises a
reformer configured to receive a fuel source, configured to output hydrogen, and
including a catalyst that facilitates the production of hydrogen; a burner configured to
provide heat to the reformer; a fuel cell comprising a fuel cell stack configured to
produce electrical energy using hydrogen output by the fuel processor, the fuel cell
stack including a bi-polar plate having I) a single substrate from a first face to a
second face, ii) a first channel field disposed on the first face and having a First set of
channels formed into the first face, iii) a second channel field disposed on the second
face and having a second set of channels formed into the second face, where the
single substrate is configured to maintain separation of gases between the first set of
channels and the second set of channels, and iv) a heat transfer appendage that a)
includes a portion arranged external to the fuel cell stack and b) is in conductive
thermal communication with an internal portion of the fuel cell stack; and plumbing
configured to transport a heating medium from the fuel processor to the fuel cell;
wherein the bi-polar plate is configured to receive heat provided to the fuel cell using

the heating medium at the externally arranged heat transfer appendage and configured
to conduct the heat to the internal portion of the fuel cell stack.
These and other features and advantages of the present invention will be
described in the following description of the invention and associated figures.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
FIG. 1A illustrates a fuel cell system for producing electrical energy in
accordance with one embodiment of the present invention.
FIG. 1B illustrates schematic operation for the fuel cell system of FIG. 1A in
accordance with a specific embodiment of the present invention.
FIG. 2A illustrates a cross sectional view of a fuel cell stack for use in the fuel
cell of FIG. 1A in accordance with one embodiment of the present invention.
FIG. 2B illustrates an outer top perspective view of a fuel cell stack and fuel
cell in accordance with another embodiment of the present invention.
FIG. 2C illustrates a ion conductive membrane fuel cell (PEMFC) architecture
for the fuel cell of FIG. 1A in accordance with one embodiment of the present
invention.

FIG. 2D illustrates a top perspective view of bi-polar plates in accordance
with one embodiment of the present invention.
FIG. 2E illustrates a widely used and conventional bi-polar plate that
comprises a plate/cooling layer/plate architecture.
FIG. 2F illustrates a cross sectional view of a fuel cell stack for use in the fuel
cell of FIG. 1A in accordance with another embodiment of the present invention.
FIG. 3 A illustrates a cross-sectional side view of a fuel processor used in the
fuel cell system of FIG. 1A in accordance with one embodiment of the present
invention.
FIG. 3B illustrates a cross-sectional front view of the fuel processor used in
the fuel cell system of FIG. 1A taken through a mid-plane of fuel processor.
FIG. 4A illustrates a heat efficient fuel cell system in accordance with one
embodiment of the present invention.
FIG. 4B illustrates a heat efficient fuel cell system in accordance with another
embodiment of the present invention.
FIG. 5 illustrates a process flow for generating electrical energy in a fuel cell
that receives hydrogen from a fuel processor in accordance with one embodiment of
the present invention.
FIG. 6 illustrates an embodiment of the fuel cell system of FIG. 1A that routes
hydrogen from an anode exhaust of the fuel cell back to a burner in the fuel
processor.
FIG. 7 illustrates a process flow for shutting down a fuel cell system
comprising a fuel cell that received hydrogen from a fuel processor in accordance
with one embodiment of the present invention.
FIG. 8 illustrates a schematic operation for a fuel cell system in accordance
with another specific embodiment of the present invention.
FIG. 9 illustrates of a system for producing electrical energy for a portable
electronics device in accordance with one embodiment of the present invention.

FIG. 10A illustrates a system for heating a fuel source before catalytic heat
generation within burner 30 in accordance with one embodiment of the present
invention.
FIG. 10B illustrates a process flow for starting up a fuel processor in
accordance with one embodiment of the present invention.
FIG. 10C illustrates a system for electrically heating a reformer in accordance
with one embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is described in detail with reference to a few preferred
embodiments as illustrated in the accompanying drawings. In the following
description, numerous specific details are set forth in order to provide a thorough
understanding of the present invention. It will be apparent, however, to one skilled in
the art, that the present invention may be practiced without some or all of these
specific details. In other instances, well known process steps and/or structures have
not been described in detail in order to not unnecessarily obscure the present
invention.
1. FUEL CELL SYSTEM
FIG. 1A illustrates a fuel cell system 10 for producing electrical energy in
accordance with one embodiment of the present invention. Fuel cell system 10
comprises a hydrogen fuel supply 12 and a fuel cell 20.
Hydrogen supply 12 provides hydrogen to fuel cell 20. As shown, supply 12
includes a 'reformed' hydrogen supply that processes a fuel source to produce
hydrogen. Fuel source 17 acts as a carrier for hydrogen and can be processed to
separate hydrogen. Fuel source 17 may include any hydrogen bearing fuel stream,
hydrocarbon fuel or other hydrogen fuel source such as ammonia. Currently available
hydrocarbon fuel sources 17 suitable for use with the present invention include
methanol, ethanol, gasoline, propane, butane and natural gas, for example. Several
hydrocarbon and ammonia products may also produce a suitable fuel source 17.

Liquid fuel sources 17 offer high energy densities and the ability to be readily stored
and shipped. Storage device 16 may contain a fuel mixture. When the fuel processor
15 comprises a steam reformer, storage device 16 may contain a fuel mixture of a
hydrocarbon fuel source and water. Hydrocarbon fuel source/water fuel mixtures are
frequently represented as a percentage fuel source in water. In one embodiment, fuel
source 17 comprises methanol or ethanol concentrations in water in the range of 1%-
99.9%. Other liquid fuels such as butane, propane, gasoline, military grade "JP8" etc.
may also be contained in storage device 16 with concentrations in water from 5-
100%. In a specific embodiment, fuel source 17 comprises 67% methanol by volume.
As shown, the reformed hydrogen supply comprises a fuel processor 15 and a
fuel source storage device 16. Storage device 16 stores fuel source 17, and may
comprise a portable and/or disposable fuel cartridge. A disposable cartridge offers a
user instant recharging. In one embodiment, the cartridge includes a collapsible
bladder within a hard plastic case. A separate fuel pump typically controls fuel source
17 flow from storage device 16. If system 10 is load following, then a control system
meters fuel source 17 to deliver fuel source 17 to processor 15 at a flow rate
determined by the required power level output of fuel cell 20.
Fuel processor 15 processes the hydrocarbon fuel source 17 and outputs
hydrogen. A hydrocarbon fuel processor 15 heats and processes a hydrocarbon fuel
source 17 in the presence of a catalyst to produce hydrogen. Fuel processor 15
comprises a reformer, which is a catalytic device that converts a liquid or gaseous
hydrocarbon fuel source 17 into hydrogen and carbon dioxide. As the term is used
herein, reforming refers to the process of producing hydrogen from a fuel source.
Fuel processor 15 is described in further detail below.
Fuel cell 20 electrochemically converts hydrogen and oxygen to water,
generating electrical energy and heat in the process. Ambient air commonly supplies
oxygen for fuel cell 20. A pure or direct oxygen source may also be used for oxygen
supply. The water often forms as a vapor, depending on the temperature of fuel cell
20 components. The electrochemical reaction also produces carbon dioxide as a
byproduct for many fuel cells.
In one embodiment, fuel cell 20 is a low volume ion conductive membrane
(PEM) fuel cell suitable for use with portable applications such as consumer

electronics. A ion conductive membrane fuel cell comprises a membrane electrode
assembly that carries out the electrical energy generating electrochemical reaction.
The membrane electrode assembly includes a hydrogen catalyst, an oxygen catalyst
and a ion conductive membrane that a) selectively conducts protons and b)
electrically isolates the hydrogen catalyst from the oxygen catalyst. A hydrogen gas
distribution layer contains the hydrogen catalyst and allows the diffusion of hydrogen
therethrough. An oxygen gas distribution layer contains the oxygen catalyst and
allows the diffusion of oxygen and hydrogen protons therethrough. The ion
conductive membrane separates the hydrogen and oxygen gas distribution layers. In
chemical terms, the anode comprises the hydrogen gas distribution layer and
hydrogen catalyst, while the cathode comprises the oxygen gas distribution layer and
oxygen catalyst.
A PEM fuel cell often includes a fuel cell stack having a set of bi-polar plates.
A membrane electrode assembly is disposed between two bi-polar plates. Hydrogen
distribution 43 occurs via a channel field on one plate while oxygen distribution 45
occurs via a channel field on a second facing plate. Specifically, a first channel field
distributes hydrogen to the hydrogen gas distribution layer, while a second channel
field distributes oxygen to the oxygen gas distribution layer. The 'term 'bi-polar'
refers electrically to a bi-polar plate (whether comprised of one plate or two plates)
sandwiched between two membrane electrode assembly layers. In this case, the bi-
polar plate acts as both a negative terminal for one adjacent membrane electrode
assembly and a positive terminal for a second adjacent membrane electrode assembly
arranged on the opposite face of the bi-polar plate.
In electrical terms, the anode includes the hydrogen gas distribution layer,
hydrogen catalyst and bi-polar plate. The anode acts as the negative electrode for fuel
cell 20 and conducts electrons that are freed from hydrogen molecules so that they
can be used externally, e.g., to power an external circuit. In a fuel cell stack, the bi-
polar plates are connected in series to add the potential gained in each layer of the
stack. In electrical terms, the cathode includes the oxygen gas distribution layer,
oxygen catalyst and bi-polar plate. The cathode represents the positive electrode for
fuel cell 20 and conducts the electrons back from the external electrical circuit to the
oxygen catalyst, where they can recombine with hydrogen ions and oxygen to form
water.

The hydrogen catalyst separates the hydrogen into protons and electrons. The
ion conductive membrane blocks the electrons, and electrically isolates the chemical
anode (hydrogen gas distribution layer and hydrogen catalyst) from the chemical
cathode. The ion conductive membrane also selectively conducts positively charged
ions. Electrically, the anode conducts electrons to a load (electrical energy is
produced) or battery (energy is stored). Meanwhile, protons move through the ion
conductive membrane. The protons and used electrons subsequently meet on the
cathode side, and combine with oxygen to form water. The oxygen catalyst in the
oxygen gas distribution layer facilitates this reaction. One common oxygen catalyst
comprises platinum powder very thinly coated onto a carbon paper or cloth. Many
designs employ a rough and porous catalyst to increase surface area of the platinum
exposed to the hydrogen and oxygen.
In one embodiment, fuel cell 20 comprises a set of bi-polar plates formed
from a single plate. Each plate includes channel fields on opposite faces of the plate.
The single bi-polar plate thus dually distributes hydrogen and oxygen: one channel
field distributes hydrogen while a channel field on the opposite face distributes
oxygen. Multiple bi-polar plates can be stacked to produce a 'fuel cell stack' in which
a membrane electrode assembly is disposed between each pair of adjacent bi-polar
plates.
Since the electrical generation process in fuel cell 20 is exothermic, fuel cell
20 may implement a thermal management system to dissipate heat from the fuel cell.
Fuel cell 20 may also employ a number of humidification plates (HP) to manage
moisture levels in the fuel cell. Further description of a fuel cell suitable for use with
the present invention is included in commonly owned co-pending patent application
entitled "Micro Fuel Cell Architecture" naming Ian Kaye as inventor and filed on the
same day as this patent application, which is incorporated by reference for all
purposes.
While the present invention will mainly be discussed with respect to PEM fuel
cells, it is understood that the present invention may be practiced with other fuel cell
architectures. The main difference between fuel cell architectures is the type of ion
conductive membrane used. In one embodiment, fuel cell 20 is phosphoric acid fuel
cell that employs liquid phosphoric acid for ion exchange. Solid oxide fuel cells

employ a hard, non-porous ceramic compound for ion exchange and may be suitable
for use with the present invention. Generally, any fuel cell architecture may benefit
from one or more systems and controls improvements described herein. Other such
fuel cell architectures include direct methanol, alkaline and molten carbonate fuel
cells.
Fuel cell 20 generates dc voltage that may be used in a wide variety of
applications. For example, electrical energy generated by fuel cell 20 may be used to
power a motor or light. In one embodiment, the present invention provides 'small'
fuel cells that are configured to output less than 200 watts of power (net or total). Fuel
cells of this size are commonly referred to as 'micro fuel cells' and are well suited for
use with portable electronics devices. In one embodiment, fuel cell 20 is configured
to generate from about 1 milliwatt to about 200 watts. In another embodiment, fuel
cell 20 generates from about 3 W to about 20 W. Fuel cell 20 may also be a stand-
alone fuel cell, which is a single unit that produces power as long as it has an a)
oxygen and b) hydrogen or a hydrocarbon fuel supply. A stand-alone fuel cell 20 that
outputs from about 40W to about 100W is well suited for use in a laptop computer.
In one embodiment, fuel processor 15 is a steam reformer that only needs
steam to produce hydrogen. Several types of reformers suitable for use in fuel cell
system 10 include steam reformers, auto thermal reformers (ATR) or catalytic partial
oxidizers (CPOX). ATR and CPOX reformers mix air with the fuel and steam mix.
ATR and CPOX systems reform fuels such as methanol, diesel, regular unleaded
gasoline and other hydrocarbons. In a specific embodiment, storage device 16
provides methanol 17 to fuel processor 15, which reforms the methanol at about
250°C or less and allows fuel cell system 10 use in applications where temperature is
to be rrnnimized.
FIG. IB illustrates schematic operation for fuel cell system 10 in accordance
with a specific embodiment of the present invention. As shown, fuel cell system 10
comprises fuel container 16, hydrogen fuel source 17, fuel processor 15, fuel cell 20,
multiple pumps 21 and fans 35, fuel lines and gas lines, and one or more valves 23.
Fuel container 16 stores methanol as a hydrogen fuel source 17. An outlet 26
of fuel container 16 provides methanol 17 into hydrogen fuel source line 25. As
shown, line 25 divides into two lines: a first line 27 that transports methanol 17 to a

burner 30 for fuel processor 15 and a second line 29 that transports methanol 17 to
reformer 32 in fuel processor 15. lines 25, 27 and 29 may comprise plastic tubing,
for example. Separate pumps 21a and 21b are provided for lines 27 and 29,
respectively, to pressurize die lines and transmit me fuel source at independent rates if
desired. A model P625 pump as provided by Instech of Plymouth Meeting, PA is
suitable to transmit liquid methanol for system 10 is suitable in this embodiment. A
flow sensor or valve 23 situated on line 29 between storage device 16 and fuel
processor 15 detects and communicates the amount of methanol 17 transfer between
storage device 16 and reformer 32. In conjunction with the sensor or valve 23 and
suitable control, such as digital control applied by a processor that implements
instructions from stored software, pump 21b regulates methanol 17 provision from
storage device 16 to reformer 32.
Fan 35a delivers oxygen and air from the ambient room through line 31 to
regenerator 36 of fuel processor 15. Fan 35b delivers oxygen and air from the
ambient room through line 33 to regenerator 36 of fuel processor 15. In this
embodiment, a model AD2005DX-K70 fan as provided by Adda USA of California
is suitable to transmit oxygen and air for fuel cell system 10. A fan 37 blows cooling
air over fuel cell 20 and its heat transfer appendages 46.
Fuel processor 15 receives methanol 17 from storage device 16 and outputs
hydrogen. Fuel processor 15 comprises burner 30, reformer 32, boiler 34 and dewar
150. Burner 30 includes an inlet that receives methanol 17 from line 27 and a catalyst
that generates heat with methanol presence. Boiler 34 includes an inlet that receives
methanol 17 from line 29. The structure of boiler 34 permits heat produced in burner
30 to heat methanol 17 in boiler 34 before reformer 32 receives the methanol 17.
Boiler 34 includes an outlet that provides heated methanol 17 to reformer 32.
Reformer 32 includes an inlet that receives heated medianol 17 from boiler 34. A
catalyst in reformer 32 reacts with the methanol 17 and produces hydrogen and
carbon dioxide. This reaction is slightly endothermic and draws heat from burner 30.
A hydrogen oudet of reformer 32 outputs hydrogen to line 39. In one embodiment,
fuel processor 15 also includes a preferential oxidizer that intercepts reformer 32
hydrogen exhaust and decreases the amount of carbon monoxide in the exhaust. The
preferential oxidizer employs oxygen from an air inlet to the preferential oxidizer and

a catalyst, such as ruthenium or platinum, that is preferential to carbon monoxide over
carbon dioxide.
Dewar 150 pre-heats air before die air enters burner 30. Dewar 150 also
reduces heat loss from fuel cell 20 by heating the incoming air before it escapes fuel
processor 15. In one sense, dewar 150 acts as a regenerator that uses waste heat in
fuel processor 15 to increase thermal management and thermal efficiency of the fuel
processor. Specifically, waste heat from burner 30 may be used to pre-heat incoming
air provided to burner 30 to reduce heat transfer to the air in the burner so more heat
transfers to reformer 32.
Line 39 transports hydrogen from fuel processor 15 to fuel cell 20. Gaseous
delivery lines 31, 33 and 39 may comprise plastic tubing, for example. A hydrogen
flow sensor (not shown) may also be added on line 39 to detect and communicate the
amount of hydrogen being delivered to fuel cell 20. In conjunction with the hydrogen
flow sensor and suitable control, such as digital control applied by a processor that
implements instructions from stored software, fuel processor 15 regulates hydrogen
gas provision to fuel cell 20.
Fuel cell 20 includes an hydrogen inlet port that receives hydrogen from line
39 and delivers it to a hydrogen intake manifold for delivery to one or more bi-polar
plates and meir hydrogen distribution channels. An oxygen inlet port of fuel cell 20
receives oxygen from line 33 and delivers it to an oxygen intake manifold for delivery
to one or more bi-polar plates and their oxygen distribution channels. An anode
exhaust manifold collects gases from the hydrogen distribution channels and delivers
them to an anode exhaust port, which oudets me exhaust gases into the ambient room.
A cathode exhaust manifold collects gases from the oxygen distribution channels and
delivers them to a cathode exhaust port.
In addition to the components shown in shown in FIG. 1B, system 10 may
also include other elements such as electronic controls, additional pumps and valves,
added system sensors, manifolds, heat exchangers and electrical interconnects useful
for carrying out functionality of a fuel cell system 10 that are known to one of skill in
the art and omitted herein for sake of brevity.

2. FUEL CELL
FIG. 2A illustrates a cross sectional view of a fuel cell stack 60 for use in fuel
cell 20 in accordance with one embodiment of the present invention. FIG. 2B
illustrates an outer top perspective view of a fuel cell stack 60 and fuel cell 20 in
accordance with another embodiment of the present invention.
Referring initially to FIG. 2A, fuel cell stack 60 is a bi-polar plate stack that
comprises a set of bi-polar plates 44 and a set of membrane electrode assembly
(MEA) layers 62. Two MEA layers 62 neighbor each bi-polar plate 44. With the
exception of topmost and bottommost membrane electrode assembly layers 62a and
62b, each MEA 62 is disposed between two adjacent bi-polar plates 44. For MEAs
62a and 62b, top and bottom end plates 64a and 64b include a channel field 72 on the
face neighboring an MEA 62.
The bi-polar plates 44 in stack 60 also each include two heat transfer
appendages 46. More specifically, each bi-polar plate 44 includes a heat transfer
appendage 46a on one side of the plate and a heat transfer appendage 46b on the
opposite side. Heat transfer appendages 46 are discussed in further detail below.
As shown, stack 60 includes twelve membrane electrode assembly layers 62,
eleven bi-polar plates 44 and two end plates 64. The number of bi-polar plates 44 and
MEA layers 62 in each set may vary with design of fuel cell stack 60. Stacking
parallel layers in fuel cell stack 60 permits efficient use of space and increased power
density for fuel cell 20. In one embodiment, each membrane electrode assembly 62
produces 0.7 V and the number of MEA layers 62 is selected to achieve a desired
voltage. Alternatively, the number of MEA layers 62 and bi-polar plates 44 may be
determined by the allowable thickness in an electronics device. A fuel cell stack 60
having from one MEA 62 to several hundred MEAs 62 is suitable for many
applications. A stack 60 having from about three MEAs 62 to about twenty MEAs 62
is also suitable for numerous applications. Fuel cell 20 size and layout may also be
tailored and configured to output a given power.
Referring to FIG. 2B, top and bottom end plates 64a and 64b provide
mechanical protection for stack 60. End plates 64 also hold the bi-polar plates 44 and
MEA layers 62 together, and apply pressure across the planar area of each bi-polar

plate 44 and each MEA 62. Bolts 82a and 82b connect and secure top and bottom end
plates 64a and 64b together.
Fuel cell 20 includes two anode ports that open to the outside of fuel cell stack
60: an inlet anode port or inlet hydrogen port 84, and an outlet anode port or outlet
hydrogen port 86. Inlet hydrogen port 84 is disposed on top end plate 64a, couples
with an inlet line to receive hydrogen gas, and opens to an inlet hydrogen manifold
102 (see FIG. 2D) that is configured to deliver inlet hydrogen gas to a channel field
72 on each bi-polar plate 44 in stack 60. Outlet port 86 receives outlet gases from an
anode exhaust manifold 104 (see FIG. 2D) that is configured to collect waste products
from the anode channel fields 72 of each bi-polar plate 44. Outlet port 86 may
provide the exhaust gases to the ambient space about the fuel cell output the gases to
a line that couples to port 86 for transportation of the anode exhaust gases as
described below.
Fuel cell 20 includes two cathode ports: an inlet cathode port or inlet oxygen
port 88, and an outlet cathode port or outlet water/vapor port 90. Inlet oxygen port 88
is disposed on bottom end plate 64b (see FIG. 2A), couples with an inlet line to
Teceive ambient air, and opens to an oxygen manifold 106 that is configured to
deliver inlet oxygen and ambient air to a channel field 72 on each bi-polar plate 44 in
stack 60. Outlet water/vapor port 90 receives outlet gases from a cathode exhaust
manifold 108 (see FIG. 2D) that is configured to collect water (typically as a vapor)
from the cathode channel fields 72 on each bi-polar plate 44.
FIG. 2C illustrates a ion conductive membrane fuel cell (PEMFC) architecture
120 for use in fuel cell 20 in accordance with one embodiment of the present
invention. As shown, PEMFC architecture 120 comprises two bi-polar plates 44 and a
membrane electrode assembly layer (or MEA) 62 sandwiched between the two bi-
polar plates 44. The MEA 62 electrochemically converts hydrogen and oxygen to
water, generating electrical energy and heat in the process. Membrane electrode
assembly 62 includes an anode gas diffusion layer 122, a cathode gas diffusion layer
124, a hydrogen catalyst 126, ion conductive membrane 128, anode electrode 130,
cathode electrode 132, and oxygen catalyst 134.
Pressurized hydrogen gas (H2) enters fuel cell 20 via hydrogen port 84,
proceeds through inlet hydrogen manifold 102 and through hydrogen channels 74 of a

hydrogen channel field 72a disposed on the anode face 75 of bi-polar plate 44a. The
hydrogen channels 74 open to anode gas diffusion layer 122, which is disposed
between the anode face 75 of bi-polar plate 44a and ion conductive membrane 128.
The pressure forces hydrogen gas into the hydrogen-permeable anode gas diffusion
layer 122 and across the hydrogen catalyst 126, which is disposed in the anode gas
diffusion layer 122. When an H2 molecule contacts hydrogen catalyst 126, it splits
into two H+ ions (protons) and two electrons (e-). The protons move through the ion
conductive membrane 128 to combine with oxygen in cathode gas diffusion layer
124. The electrons conduct through the anode electrode 130, where they build
potential for use in an external circuit (e.g., a power supply of a laptop computer)
After external use, the electrons flow to the cathode electrode 132 of PEMFC
architecture 120.
Hydrogen catalyst 126 breaks hydrogen into protons and electrons. Suitable
catalysts 126 include platinum, ruthenium, and platinum black or platinum carbon,
and/or platinum on carbon nanotubes, for example. Anode gas diffusion layer 122
comprises any material that allows the diffusion of hydrogen therethrough and is
capable of holding the hydrogen catalyst 126 to allow interaction between the catalyst
and hydrogen molecules. One such suitable layer comprises a woven or non-woven
carbon paper. Other suitable gas diffusion layer 122 materials may comprise a silicon
carbide matrix and a mixture of a woven or non-woven carbon paper and Teflon.
On the cathode side of PEMFC architecture 120, pressurized air carrying
oxygen gas (O2) enters fuel cell 20 via oxygen port 88, proceeds through inlet oxygen
manifold 106, and through oxygen channels 76 of an oxygen channel field 72b
disposed on the cathode face 77 of bi-polar plate 44b. The oxygen channels 76 open
to cathode gas diffusion layer 124, which is disposed between the cathode face 77 of
bi-polar plate 44b and ion conductive membrane 128. The pressure forces oxygen
into cathode gas diffusion layer 124 and across the oxygen catalyst 134 disposed in
the cathode gas diffusion layer 124. When an O2 molecule contacts oxygen catalyst
134, it splits into two oxygen atoms. Two H+ ions that have traveled through the ion
selective ion conductive membrane 128 and an oxygen atom combine with two
electrons returning from the external circuit to form a water molecule (H2O). Cathode
channels 76 exhaust the water, which usually forms as a vapor. This reaction in a
single MEA layer 62 produces about 0.7 volts.


Cathode gas diffusion layer 124 comprises a material that permits diffusion of
oxygen and hydrogen protons therethrough and is capable of holding the oxygen
catalyst 134 to allow interaction between the catalyst 134 with oxygen and hydrogen.
Suitable gas diffusion layers 124 may comprise carbon paper or cloth, for example.
Other suitable gas diffusion layer 124 materials may comprise a silicon carbide
matrix and a mixture of a woven or non-woven carbon paper and Teflon. Oxygen
catalyst 134 facilitates the reaction of oxygen and hydrogen to form water. One
common catalyst 134 comprises platinum. Many designs employ a rough and porous
catalyst 134 to increase surface area of catalyst 134 exposed to the hydrogen or
oxygen. For example, the platinum may reside as a powder very thinly coated onto a
carbon paper or cloth cathode gas diffusion layer 124.
Ion conductive membrane 128 electrically isolates the anode from the
cathode by blocking electrons from passing through membrane 128. Thus, membrane
128 prevents the passage of electrons between gas diffusion layer 122 and gas
diffusion layer 124. Ion conductive membrane 128 also selectively conducts
positively charged ions, e.g., hydrogen protons from gas diffusion layer 122 to gas
diffusion layer 124. For fuel cell 20, protons move through membrane 128 and
electrons are conducted away to an electrical load or battery. In one embodiment, ion
conductive membrane 128 comprises an electrolyte. One electrolyte suitable for use
with fuel cell 20 is Celtec 1000 from PEMEAS USA AG of Murray Hill, NJ
(www.pemeas.com). Fuel cells 20 including this electrolyte are generally more
carbon monoxide tolerant and may not require humidification. Ion conductive
membrane 128 may also employ a phosphoric acid matrix that includes a porous
separator impregnated with phosphoric acid. Alternative ion conductive membranes
128 suitable for use with fuel cell 20 are widely available from companies such as
United technologies, DuPont, 3M, and other manufacturers known to those of skill in
the art. For example, WL Gore Associates of Elkton, MD produces the primea Series
58, which is a low temperature MEA suitable for use with the present invention.
In one embodiment, fuel cell 20 requires no external humidifier or heat
exchanger and the stack 60 only needs hydrogen and air to produce electrical power.
Alternatively, fuel cell 20 may employ humidification of the cathode to fuel cell 20
improve performance. For some fuel cell stack 60 designs, humidifying the cathode
increases the power and operating life of fuel cell 20.

FIG. 2D illustrates a top perspective view of bi-polar plates 44p and 44q in
accordance with one embodiment of the present invention. Bi-polar plate 44 is a
single plate 44 with a first channel fields 72 disposed on opposite faces 75 of the plate
44.
Functionally, bi-polar plate 44 a) delivers and distributes reactant gasses to the
gas diffusion layers 122 and 124 and their respective catalysts, b) maintains
separation of the reactant gasses from one another between MEA layers 62 in stack
60, c) exhausts electrochemical reaction byproducts from MEA layers 62, d)
facilitates heat transfer to and/or from MEA layers 62 and fuel cell stack 60, and e)
includes gas intake and gas exhaust manifolds for gas delivery to other bi-polar plates
44 in the fuel stack 60.
Structurally, bi-polar plate 44 has a relatively flat profile and includes
opposing top and bottom faces 75a and 75b (only top face 75a is shown) and a
number of sides 78. Faces 75 are substantially planar with the exception of channels
76 formed as troughs into substrate 89. Sides 78 comprise portions of bi-polar plate
44 proximate to edges of bi-polar plate 44 between the two faces 75. As shown, bi-
polar plate 44 is roughly quadrilateral with features for the intake manifolds, exhaust
manifolds and heat transfer appendage 46 that provide deviation from the
quadrilateral shape.
The manifold on each plate 44 is configured to deliver a gas to a channel field
on a face of the plate 44 or receive a gas from the channel field 72. The manifolds for
bi-polar plate 44 include apertures or holes in substrate 89 that, when combined with
manifolds of other plates 44 in a stack 60, form an inter-plate 44 gaseous
communication manifold (such as 102,104,106 and 108). Thus, when plates 44 are
stacked and their manifolds substantially align, the manifolds permit gaseous delivery
to and from each plate 44.
Bi-polar plate 44 includes a channel field 72 or "flow field" on each face of
plate 44. Each channel field 72 includes one or more channels 76 formed into the
substrate 89 of plate 44 such that the channel rests below the surface of plate 44. Each
channel field 72 distributes one or more reactant gasses to an active area for the fuel
cell stack 60. Bi-polar plate 44 includes a first channel field 72a on the anode face
75a of bi-polar plate 44 that distributes hydrogen to an anode (FIG. 2C), while a

second channel field on opposite cathode face 75b distributes oxygen to a cathode.
Specifically, channel field 72a includes multiple channels 76 that permit oxygen and
air flow to anode gas diffusion layer 122, while channel field 72b includes multiple
channels 76 that permit oxygen and air flow to cathode gas diffusion layer 124. For
fuel cell stack 60, each channel field 72 is configured to receive a reactant gas from
an intake manifold 102 or 106 and configured to distribute the reactant gas to a gas
diffusion layer 122 or 124. Each channel field 72 also collects reaction byproducts for
exhaust from fuel cell 20. When bi-polar plates 44 are stacked together in fuel cell 60,
adjacent plates 44 sandwich an MEA layer 62 such that the anode face 75a from one
bi-polar plate 44 neighbors a cathode face 75b of an adjacent bi-polar plate 44 on an
opposite side of the MEA layer 62.
Bi-polar plate 44 may include one or more heat transfer appendages 46. Heat
transfer appendage 46 permits external thermal management of internal portions of
fuel cell stack 60. More specifically, appendage 46 may be used to heat or cool
internal portions of fuel cell stack 60 such as internal portions of each attached bi-
polar plate 44 and any neighboring MEA layers 62, for example. Heat transfer
appendage 46 is laterally arranged outside channel field 72. In one embodiment,
appendage 46 is disposed on an external portion of bi-polar plate 44. External
portions of bi-polar plate 44 include any portions of plate 44 proximate to a side or
edge of the substrate included in plate 44. External portions of bi-polar plate 44
typically do not include a channel field 72. For the embodiment shown, heat transfer
appendage 46 substantially spans a side of plate 44 that does not include intake and
output manifolds 102-108. For the embodiment shown in FIG. 2A, plate 44 includes
two heat transfer appendages 46 that substantially span both sides of plate 44 that do
not include a gas manifold.
Peripherally disposing heat transfer appendage 46 allows heat transfer
between inner portions of plate 44 and the externally disposed appendage 46 via the
plate substrate 89. Conductive thermal communication refers to heat transfer between
bodies that are in contact or that are integrally formed. Thus, lateral conduction of
heat between external portions of plate 44 (where the heat transfer appendage 46
attaches) and central portions of bi-polar plate 44 occurs via conductive thermal
communication through substrate 89. In one embodiment, heat transfer appendage 46
is integral with substrate material 89 in plate 44. Integral in this sense refers to

material continuity between appendage 46 and plate 44. An integrally formed
appendage 46 may be formed with plate 44 in a single molding, stamping, machining
or MEMs process of a single metal sheet, for example. Integrally forming appendage
46 and plate 44 permits conductive thermal communication and heat transfer between
inner portions of plate 44 and the heat transfer appendage 46 via substrate 89. In
another embodiment, appendage 46 comprises a material other than that used in
substrate 89 that is attached onto plate 44 and conductive thermal communication and
heat transfer occurs at the junction of attachment between the two attached materials.
Heat may travel to or form the heat transfer appendage 46. In other words,
appendage 46 may be employed as a heat sink or source. Thus, heat transfer
appendage 46 may be used as a heat sink to cool internal portions of bi-polar plate 44
or an MEA 62. Fuel cell 20 employs a cooling medium to remove heat from
appendage 46. Alternatively, heat transfer appendage 46 may be employed as a heat
source to provide heat to internal portions of bi-polar plate 44 or an MEA 62. In this
case, a catalyst may be disposed on appendage 46 to generate heat in response to the
presence of a heating medium.
For cooling, heat transfer appendage 46 permits integral conductive heat
transfer from inner portions of plate 44 to the externally disposed appendage 46.
During hydrogen consumption and electrical energy production, the electrochemical
reaction generates heat in each MEA 62. Since internal portions of bi-polar plate 44
are in contact with the MEA 62, a heat transfer appendage 46 on a bi-polar plate 44
thus cools an MEA 62 adjacent to the plate via a) conductive heat transfer from MEA
62 to bi-polar plate 44 and b) lateral thermal communication and conductive heat
transfer from central portions of the bi-polar plate 44 in contact with the MEA 62 to
the external portions of plate 44 that include appendage 46. In this case, heat transfer
appendage 46 sinks heat from substrate 89 between a first channel field 72 on one
face 75 of plate 44 and a second channel field 72 on the opposite face of plate 44 to
heat transfer appendage 46 in a direction parallel to a face 75 of plate 44. When a fuel
cell stack 60 includes multiple MEA layers 62, lateral thermal communication
through each bi-polar plate 44 in this manner provides interlayer cooling of multiple
MEA layers 62 in stack 60 - including those layers in central portions of stack 60.

Fuel cell 20 may employ a cooling medium that passes over heat transfer
appendage 46. The cooling medium receives heat from appendage 46 and removes
the heat from fuel cell 20. Heat generated internal to stack 60 thus conducts through
bi-polar plate 44, to appendage 46, and heats the cooling medium via convective heat
transfer between the appendage 46 and cooling medium. Air is suitable for use as the
cooling medium.
As shown, heat transfer appendage 46 may be configured with a thickness that
is less than the thickness between opposite faces 75 of plate 44. The reduced
thickness of appendages 46 on adjacent bi-polar plates 44 in the fuel cell stack 60
forms a channel 190 between adjacent appendages. Multiple adjacent bi-polar plates
44 and appendages 46 in stack form numerous channels 190. Each channel 190
permits a cooling medium or heating medium to pass therethrough and across heat
transfer appendages 46. In one embodiment, fuel cell stack 60 includes a mechanical
housing that encloses and protects stack 60. Walls of the housing also provide
additional ducting for the cooling or heating medium by forming ducts between
adjacent appendages 46 and the walls.
The cooling medium may be a gas or liquid. Heat transfer advantages gained
by high conductance bi-polar plates 44 allow air to be used as a cooling medium to
cool heat transfer appendages 46 and stack 60. For example, a dc-fan may be attached
to an external surface of the mechanical housing. The fan moves air through a hole in
the mechanical housing, through channels 190 to cool heat transfer appendages 46
and fuel cell stack 60, and out an exhaust hole or port in the mechanical housing. Fuel
cell system 10 may then include active thermal controls. Increasing or decreasing
coolant fan speed regulates the amount of heat removal from stack 60 and the
operating temperature for stack 60. In one embodiment of an air-cooled stack 60, the
coolant fan speed increases or decreases as a function of the actual cathode exit
temperature, relative to a desired temperature set-point.
For heating, heat transfer appendage 46 allows integral heat transfer from the
externally disposed appendage 46 to inner portions of plate 44 and any components
and portions of fuel cell 20 in thermal communication with inner portions of plate 44.
A heating medium passed over the heat transfer appendage 46 provides heat to the
appendage. Heat convected onto the appendage 46 then conducts through the

substrate 89 and into internal portions of plate 44 and stack 60, such as portions of
MEA 62 and its constituent components.
In one embodiment, the heating medium comprises a heated gas having a
temperature greater than that of appendage 46. As will be described below, exhaust
gases from burner 30 or reformer 32 of fuel processor 15 may each include elevated
temperatures that are suitable for heating one or more appendages 46.
In another embodiment, fuel cell comprises a catalyst 192 disposed in contact
with, or in proximity to, a heat transfer appendage 46. The catalyst 192 generates heat
when the heating medium passes over it. The heating medium in this case may
comprise any gas or fluid that reacts with catalyst 192 to generate heat. Typically,
catalyst 192 and the heating medium employ an exothermic chemical reaction to
generate the heat. Heat transfer appendage 46 and plate 44 then transfer heat into the
fuel cell stack 60, e.g. to heat internal MEA layers 62. For example, catalyst 192 may
comprise platinum and the heating medium includes the hydrocarbon fuel source 17
supplied to fuel processor 15 (FIGs. 2A and 2F). The fuel source 17 may be heated to
a gaseous state before it enters fuel cell 20. This allows gaseous transportation of the
heating medium and gaseous interaction between the fuel source 17 and catalyst 192
to generate heat. Similar to the cooling medium described above, a fan disposed on
one of the walls 199 then moves the gaseous heating medium within fuel cell 20.
In a specific embodiment, the hydrocarbon fuel source 17 used to react with
catalyst 192 comes from a reformer exhaust or burner exhaust in fuel processor 15.
This advantageously pre-heats the fuel source 17 before receipt within fuel cell 20
and also efficiently uses or bums any fuel remaining in the reformer or burner exhaust
after processing by fuel processor 15. Alternatively, fuel cell 20 includes a separate
hydrocarbon fuel source 17 feed that directly supplies hydrocarbon fuel source 17 to
fuel cell 20 for heating and reaction with catalyst 192. In this case, catalyst 192 may
comprise platinum. Other suitable catalysts 192 include palladium, a platinum/
palladium mix, iron, ruthenium, and combinations thereof. Each of these will react
with a hydrocarbon fuel source 17 to generate heat. Other suitable heating medium
include hydrogen or any heated gases emitted from fuel processor 15, for example.
When hydrogen is used as the heating medium, catalyst 192 comprises a
material that generates heat in the presence of hydrogen, such as palladium or

platinum. As will be described in further detail below, the hydrogen may include
hydrogen supplied from the reformer 32 in fuel processor 15.
As shown in FIGs. 2A and 2F, catalyst 192 is arranged on, and in contact
with, each heat transfer appendage 46. In this case, the heating medium passes over
each appendage 46 and reacts with catalyst 192. This generates heat, which is
absorbed via conductive thermal communication by the cooler appendage 46. Wash
coating may be employed to dispose catalyst 192 on each appendage 46. A ceramic
support may also be used to bond catalyst 192 on an appendage 46.
FIG. 2F illustrates two examples in which a thermal catalyst 192 is disposed
in proximity to heat transfer appendage 46. Proximity in this case refers to being
arranged relative to heat transfer appendage 46 such that heat generated by catalyst
192 transfers to appendage 46, either by conduction, convection and/or radiation. As
shown in FIG. 2F, fuel cell 20 comprises a bulkhead 195 that contains catalyst 192.
Bulkhead 195 attaches to a heat transfer appendage 46 and either a) forms walls with
the appendage 46 that contain catalyst 192 or b) includes its own set of wall that
contain catalyst 192. Catalyst pellets 192 are then disposed in bulkhead 195. The
bulkhead 195 allows the heating medium to pass over and interact with catalyst 192.
As shown in FIG. 2F, the fuel cell 20 includes a mechanical housing 197 that
encloses and protects stack 60. Walls 199 of housing 197 and appendages 46 combine
to form ducting 193. The inter-appendage ducting 193 permits a) catalyst 192 to be
packed into the ducting 193 and b) permits the heating medium to pass through
ducting 193 and over catalyst 192. In this case, catalyst 192 is packed in ducting 193
with a packing density loose enough to permit a gas to pass therethrough without
encountering excessive resistance. A fan is then used to provide the heating medium
into ducting 193.
For catalyst-based heating, heat then a) transfers from catalyst 192 to
appendage 46, b) moves laterally though bi-polar plate 44 via conductive heat transfer
from lateral portions of the plate that include heat transfer appendage 46 to central
portions of bi-polar plate 44 in contact with the MEA layers 62, and c) conducts from
bi-polar plate 44 to MEA layer 62. When a fuel cell stack 60 includes multiple MEA
layers 62, lateral heating through each bi-polar plate 44 provides interlayer heating of
multiple MEA layers 62 in stack 60, which expedites fuel cell 20 warm up.

Bi-polar plates 44 of FIG. 2A include heat transfer appendages 46 on each
side. In this case, one set of heat transfer appendages 46a is used for cooling while the
other set of heat transfer appendages 46b is used for heating. Although heat transfer
appendages 46 of FIG. 2F are illustrated with two different types of heating via
catalyst 192 (namely, by packing into ducting 193 and storage in bulkheads 195), it is
understood that fuel cell 20 need not include multiple methods of heating appendages
46 and may only include one the aforementioned techniques. In addition, while bi-
polar plates 44 illustrated in FIGs. 2A and 2D show plates 44 with two heat transfer
appendages 46 disposed on sides of stack 60, appendage 46 arrangements can be
varied to affect and improve heat dissipation and thermal management of fuel cell
stack 60 according to other specific designs. For example, one or more than two heat
transfer appendages 46 may be employed on a single plate 44 to increase heat transfer
between internal and external portions of plate 44. In addition, appendages 46 need
not span a side of plate 44 as shown and may be tailored based on how the heating
fluid is channeled through the housing 197.
Although the present invention provides a bi-polar plate 44 having channel
fields 72 that distribute hydrogen and oxygen on opposing sides of a single plate 44,
many embodiments described herein are suitable for use with conventional bi-polar
plate assemblies that employ two separate plates for distribution of hydrogen and
oxygen. FIG. 2E illustrates a widely used and conventional bi-polar plate 300 that
comprises a plate/cooling layer/plate architecture.
Bi-polar plate 300 includes two plates 302a and 302b that sandwich a cooling
layer 304. Top plate 302a includes a channel field 306a on its top face 308 that
distributes oxygen. Bottom plate 302b includes a channel field 306b on its bottom
face 308 that distributes hydrogen (or oxygen when top plate 302a distributes
hydrogen). Cooling layer 304 runs a cooling medium such as de-ionized water
through cooling channels 310. The cooling medium actively cools each plate 302.
The cooling medium may be routed such that the temperature increase occurs in the
same direction as reducing oxygen partial pressure in the cathode. Similar to bi-polar
plate 44, bi-polar plate 300 is referred to as a 'bi-polar plate' since it acts electrically
as a cathode for one MEA and as an anode for another MEA. Bi-polar plate 300
serves similar functions for a fuel cell as those described above for bi-polar plate 44.

Top and bottom plates 302a and 302b may each comprise silicon with channels
etched in their faces to provide channel fields 306.
While the present invention has mainly been discussed so far with respect to a
reformed methanol fuel cell (RMFC), die present invention may also apply to other
types of fuel cells, such as a solid oxide fuel cell (SOFC), a phosphoric acid fuel cell
(PAFC), a direct methanol fuel cell (DMFC), or a direct ethanol fuel cell (DEFC). In
this case, fuel cell 20 includes components specific to these architectures, as one of
skill in the art will appreciate. A DMFC or DEFC receives and processes a fuel. More
specifically, a DMFC or DEFC receives liquid methanol or ethanol, respectively,
channels the fuel into the fuel cell stack 60 and processes the liquid fuel to separate
hydrogen for electrical energy generation. For a DMFC, channel fields 72 in the bi-
polar plates 44 distribute liquid methanol instead of hydrogen. Hydrogen catalyst 126
described above would then comprise a suitable anode catalyst for separating
hydrogen from medianol. Oxygen catalyst 134 would comprise a suitable cathode
catalyst for processing oxygen or another suitable oxidant used in the DMFC, such as
peroxide. In general, hydrogen catalyst 126 is also commonly referred to as an anode
catalyst in other fuel cell architectures and may comprise any suitable catalyst that
removes hydrogen for electrical energy generation in a fuel cell, such as directly from
the fuel as in a DMFC. In general, oxygen catalyst 134 may include any catalyst that
processes an oxidant in used in fuel cell 20. The oxidant may include any liquid or
gas mat oxidizes the fuel and is not limited to oxygen gas as described above. An
SOFC, PAFC or MCFC may also benefit from inventions described herein, for
example. In this case, fuel cell 20 comprises an anode catalyst 126, oxygen catalyst
134, anode fuel and oxidant according to a specific SOFC, PAFC or MCFC design.
3. FUEL PROCESSOR
FIG. 3A illustrates a cross-sectional side view of fuel processor 15 in
accordance with one embodiment of the present invention. FIG. 3B illustrates a cross-
sectional front view of fuel processor 15 taken through a mid-plane of processor 15
mat also shows features of end plate 82. Fuel processor 15 reforms methanol to
produce hydrogen. Fuel processor 15 comprises monolithic structure 100, end plates
182 and 184, reformer 32, burner 30, boiler 34, boiler 108, dewar 150 and housing

152. Although the present invention will now be described with respect to methanol
consumption for hydrogen production, it is understood that fuel processors of the
present invention may consume another fuel source, as one of skill in the art will
appreciate.
As the term is used herein, 'monolithic' refers to a single and integrated
structure that includes at least portions multiple components used in fuel processor
15. As shown, monolithic structure 100 includes reformer 32, burner 30, boiler 34
and boiler 108. Monolithic structure 100 may also include associated plumbing inlets
and outlets for reformer 32, burner 30 and boiler 34. Monolithic structure 100
comprises a common material 141 that constitutes the structure. The monolithic
structure 100 and common material 141 simplify manufacture of fuel processor 15.
For example, using a metal for common material 141 allows monolithic structure 100
to be formed by extrusion. In some cases, monolithic structure 100 is consistent in
cross sectional dimensions between end plates 82 and 84 and solely comprises copper
formed in a single extrusion.
Housing 152 provides mechanical protection for internal components of fuel
processor 15 such as burner 30 and reformer 32. Housing 152 also provides
separation from the environment external to processor 15 and includes inlet and outlet
ports for gaseous and liquid communication in and out of fuel processor 15. Housing
152 includes a set of housing walls 161 that at least partially contain a dewar 150 and
provide external mechanical protection for components in fuel processor 15. Walls
161 may comprises a suitably stiff material such as a metal or a rigid polymer, for
example. Dewar 150 improves thermal heat management for fuel processor 15 by a)
allowing incoming air to be pre-heated before entering burner 30, b) dissipating heat
generated by burner 32 into the incoming air before the heat reaches the outside of
housing 152.
Referring to FIG. 3B, boiler 34 heats methanol before reformer 32 receives
the methanol. Boiler 34 receives methanol via fuel source inlet 81, which couples to
methanol supply line 27 of FIG. 1B. Since methanol reforming and hydrogen
production via a catalyst 102 in reformer 32 often requires elevated methanol
temperatures, fuel processor 15 pre-heats the methanol before receipt by reformer 32
via boiler 34. Boiler 34 is disposed in proximity to burner 30 to receive heat

generated in burner 30. The heat transfers via conduction through monolithic
structure from burner 30 to boiler 34 and via convection from boiler 34 walls to the
methanol passing therethrough. In one embodiment, boiler 34 is configured to
vaporize liquid methanol. Boiler 34 then passes the gaseous methanol to reformer 32
for gaseous interaction with catalyst 102.
Reformer 32 is configured to receive methanol from boiler 34. Walls 111 in
monolithic structure 100 and end walls 113 on end plates 82 and 84 define
dimensions for a reformer chamber 103. In one embodiment, end plate 82 and/or end
plate 84 includes also channels 95 that route heated methanol exhausted from boiler
34 into reformer 32. The heated methanol then enters the reformer chamber 103 at
one end of monolithic structure 100 and passes to the other end where the reformer
exhaust is disposed. In another embodiment, a hole disposed in a reformer 32 wall
receives inlet heated methanol from a line or other supply. The inlet hole or port may
be disposed on a suitable wall 111 or 113 of reformer 32.
Reformer 32 includes a catalyst 102 that facilitates the production of
hydrogen. Catalyst 102 reacts with methanol 17 and produces hydrogen gas and
carbon dioxide. Li one embodiment, catalyst 102 comprises pellets packed to form a
porous bed or otherwise suitably filled into the volume of reformer chamber 103.
Pellet diameters ranging from about 50 microns to about 1.5 millimeters are suitable
for many applications. Pellet diameters ranging from about 500 microns to about 1
millimeter are suitable for use with reformer chamber 103. Pellet sizes may be varied
relative to the cross sectional size of reformer chamber 103, e.g., as reformer chamber
103 increases in size so do catalyst 102 pellet diameters. Pellet sizes and packing may
also be varied to control the pressure drop that occurs through reformer chamber 103.
hi one embodiment, pressure drops from about 0.2 to about 2 psi gauge are suitable
between the inlet and outlet of reformer chamber 103. One suitable catalyst 102 may
include CuZn coated onto alumina pellets when methanol is used as a hydrocarbon
fuel source 17. Other materials suitable for catalyst 102 include platinum, palladium,
a platinum/ palladium mix, nickel, and other precious metal catalysts for example.
Catalyst 102 pellets are commercially available from a number of vendors known to
those of skill in the art. Catalyst 102 may also comprise catalyst materials listed
above coated onto a metal sponge or metal foam. A wash coat of the desired metal

catalyst material onto the walls of reformer chamber 103 may also be used for
reformer 32.
Reformer 32 is configured to output hydrogen and includes an outlet port 87
that communicates hydrogen formed in reformer 32 outside of fuel processor 15. For
example, a line 39 may communicate to an anode of fuel cell 20 for electrical energy
generation or to a heating port for heating of a catalyst proximate to one or more heat
transfer appendages. Port 87 is disposed on a wall of end plate 82 and includes a hole
that passes through the wall (see FIG. 3B). The outlet hole port may be disposed on
any suitable wall 111 or 113.
Hydrogen production in reformer 32 is slightly endothermic and draws heat
from burner 30. Burner 30 generates heat and is configured to provide heat to
reformer 32. As shown in FIG. 3B, burner 30 comprises two burners 30a and 30b and
their respective burner chambers 105a and 105b that surround reformer 32. In one
embodiment, burner 30 uses electrical resistance and electrical energy to produce
heat.
In the embodiment shown, burner 30 employs catalytic combustion to produce
heat. A catalyst 104 disposed in each burner chamber 105 helps a burner fuel passed
through the chamber generate heat. Burner 30 includes an inlet that receives methanol
17 from boiler 108 via a channel in one of end plates 82 or 84. In one embodiment,
methanol produces heat in burner 30 and catalyst 104 facilitates the methanol
production of heat. In another embodiment, waste hydrogen from fuel cell 20
produces heat in the presence of catalyst 104. Suitable burner catalysts 104 may
include platinum or palladium coated onto alumina pellets for example. Other
materials suitable for catalyst 104 include iron, tin oxide, other noble-metal catalysts,
reducible oxides, and mixtures thereof. The catalyst 104 is commercially available
from a number of vendors known to those of skill in the art as small pellets. The
pellets that may be packed into burner chamber 105 to form a porous bed or
otherwise suitably filled into the burner chamber volume. Catalyst 104 pellet sizes
may be varied relative to the cross sectional size of burner chamber 105. Catalyst 104
may also comprise catalyst materials listed above coated onto a metal sponge or metal
foam or wash coated onto the walls of burner chamber 105. A burner outlet port 89
(FIG. 3 A) communicates exhaust formed in burner 30 outside of fuel processor 15.

Some fuel sources generate additional heat in burner 30, or generate heat more
efficiently, with elevated temperatures. Fuel processor 15 includes a boiler 108 that
heats methanol before burner 30 receives the fuel source. In this case, boiler 108
receives the methanol via fuel source inlet 85. Boiler 108 is disposed in proximity to
burner 30 to receive heat generated in burner 30. The heat transfers via conduction
through monolithic structure from burner 30 to boiler 108 and via convection from
boiler 108 walls to the methanol passing therethrough.
Air including oxygen enters fuel processor 15 via air inlet port 91. Burner 30
uses the oxygen for catalytic combustion of methanol. Dewar 150 is configured such
that air passing through dewar chamber 156 receives heat generated in burner 30.
Dewar 150 offers thus two functions for fuel processor 15: a) it permits active cooling
of components within fuel processor 15 before the heat reaches an outer portion of the
fuel processor, and b) it pre-heats the air going to burner 30. Air first passes along the
outside of dewar 150 before passing through apertures in the dewar and along the
inside of dewar 150. This heats the air before receipt by air inlet port 93 of burner 30.
A burner 30 in fuel processor 15 generates heat and typically operates at an elevated
temperature. In one embodiment, fuel processor 15 comprises a dewar 150 to improve
thermal management for fuel processor 15. Dewar 150 at least partially thermally
isolates components internal to housing 152 - such as burner 30 - and contains heat
within fuel processor 15.
Although the present invention will primarily be described with respect to the
annular reformer and burner shown in FIGs. 3A and 3B, it is anticipated that fuel cell
systems described herein are also applicable to other fuel processor designs. Many
architectures employ a planar reformer disposed on top or below to a planar burner.
Micro-channel designs fabricated in silicon commonly employ such stacked planar
architectures and would benefit from fuel cell systems described herein. Further
description of planar fuel processors suitable for use with the present invention are
included in commonly owned co-pending patent application entitled "Planar Micro
Fuel Processor" naming Ian Kaye as inventor and filed on the same day as this patent
application, which is incorporated by reference for all purposes.

4. EFFICIENT FUEL CELL SYSTEMS
Fuel processor components operate at elevated temperatures. Burner 30
temperatures from about 200 degrees Celsius to about 800 degrees Celsius are
common. Many fuel cells 20 require elevated temperatures for electrical energy
production. More specifically, the electrochemical reaction responsible for hydrogen
consumption and electrical energy generation typically requires an elevated
temperature. Start temperatures in the MEA layer 62 and its constituent parts greater
than 150 degrees Celsius are common.
One embodiment of the present invention heats internal portions of fuel cell
20 using heat generated in fuel processor 15 or gases exhausted from fuel processor
15 that can be used for catalytic combustion in fuel cell 20. FIG. 4A illustrates a heat
efficient fuel cell system 400 in accordance with one embodiment of the present
invention. System 400 runs gases exhausted from burner 30 to fuel cell 20 to provide
heat to fuel cell 20.
System 400 comprises components of system 10 described with respect to
FIG. 1B and also comprises plumbing configured to transport a heating medium from
fuel processor 15 to fuel cell 20. As the term is used herein, plumbing may comprise
any tubing, piping and/or channeling that communicates a gas or liquid from one
location to a second location. The plumbing may also comprise one or more valves,
gates or other devices to facilitate and control flow. A fan or pump may also be
included to pressurize a line and move the heating medium. Plumbing between burner
30 and fuel cell 20 includes an outlet 402 on fuel processor 15 that exhausts heated
gases from burner 30 to a line 41, which transmits the heated gases to fuel cell 20. A
'line' refers to tubing, piping and/or channeling that is dedicated for fluid or gas
communication between two locations.
In a specific embodiment, line 41 transports the heated gases to fan 37, which
moves the heated gases within fuel cell 20 and across the fuel cell stack and heat
transfer appendages. Alternatively, the plumbing may be configured to transport the
heating medium from burner 30 to one or more heat transfer appendages. In this case,
line 41 may continue through the fuel cell housing and open in the proximity of the
heat transfer appendages. A hole in the fuel cell housing then allows line 41 to pass
therethrough or connect to a port that communicates the gases to plumbing inside the

fuel cell for delivery to the fuel cell stack and heat transfer appendage. For catalytic
heat generation in fuel cell 20, the plumbing may also transport the heating medium
to facilitate gaseous interaction with the catalyst, such as plumbing delivery to one or
more bulkheads.
In one embodiment, the heating medium comprises heated gases exhausted
from burner 30. A catalytic burner or electrical resistance burner operates at elevated
temperatures. Cooling air exhausted from an electric burner or product gases
exhausted from a catalytic burner are often greater than about 100 degrees Celsius
when the gases leaves the fuel processor. For many catalytic burners, depending on
the fuel source employed, the heating medium is commonly greater than about 200
degrees Celsius when the heating medium leaves the fuel processor. These heated
gases are transported to the fuel cell for convective heat transfer in the fuel cell, such
as passing the heated gases over one or more heat transfer appendages 46 for
convective heat transfer from the warmer gases into the cooler heat transfer
appendages.
In another embodiment, burner 30 is a catalytic burner and the heating
medium comprises the fuel source. Catalytic combustion in burner 30 is often
incomplete and the burner exhaust gases include unused and gaseous methanol. Fuel
cell 20 then comprises a thermal catalyst that facilitates production of heat in the fuel
cell in the presence of methanol. The fuel source is typically vaporized prior to
reaching the burner to facilitate catalytic combustion. In this case, line 41 transports
the gaseous and unused methanol to the thermal catalyst in fuel cell 20. Several
suitable thermal catalyst arrangements for transferring heat into heat transfer
appendages 46 were described above (see FIGs. 2A and 2F). Suitable methanol
catalysts, such as platinum or palladium coated onto alumina pellets, were also
described above with respect to catalyst 104 in burner 30.
System 400 also comprises one or more sensors to help regulate thermal
management in system 400. A temperature sensor 404 detects temperature for a
component in fuel processor 15. Sensor 406 may be arranged within burner 30 for
detecting the temperatures within the burner. Other components in fuel processor 15
whose temperature may be monitored by sensor 404 include: reformer 32, boiler 34,
boiler 108 and gases at the inlet at outlet ports of each of these components. A

temperature sensor 406 detects temperature for a component in fuel cell 20. For
example, sensor 406 may be arranged in contact with the substrate 89 of one or more
bi-polar plates 44 for detecting the temperature of the plate. Other component in fuel
cell 20 whose temperature may be monitored by sensor 406 include: MEA layer 62
and gases in an inlet or outlet manifold. Suitable temperature sensors for use with the
present invention are widely commercially available from numerous sources known
to those of skill in the art.
FIG. 4B illustrates a heat efficient fuel cell system 420 in accordance with
another embodiment of the present invention. System 420 comprises plumbing
configured to transport a heating medium from reformer 32 to fuel cell 20 to provide
heat to fuel cell 20. As shown, line 422 transports reformer exhaust from an outlet
port of reformer 32 to heat transfer appendage 46. Line 422 may also transport the
reformer exhaust to fan 37, which moves the heated gases within fuel cell 20 and
across the heat transfer appendages. In another embodiment, reformer 32 includes a
single output that splits into line 422 for reformer exhaust heating in fuel cell 20 and
into line 39 for hydrogen delivery to the anode. A valve may be employed to control
flow between the two lines.
In one embodiment, the reformer exhaust is at an elevated temperature
corresponding to the temperature in reformer 32. Reformer exhausts above 100
. degrees Celsius are common. Heat in the reformer exhaust then convects onto the
heat transfer appendage to heat the fuel stack and its internal components. In another
embodiment, hydrogen production in reformer 32 is often incomplete and the
reformer exhaust gases include unused and gaseous methanol. Fuel cell 20 then
comprises a thermal catalyst that facilitates production of heat in the fuel cell in the
presence of methanol. Boiler 34 vaporizes the methanol prior to reaching reformer 32.
In this case, line 422 transports the gaseous and unused methanol to the thermal
catalyst in fuel cell 20. Suitable methanol catalysts, such as platinum or palladium
coated onto alumina pellets, were also described above with respect to catalyst 104 in
burner 30. Alternatively, fuel cell 20 may include a thermal catalyst that facilitates
production of heat in the fuel cell in the presence of hydrogen. In this case, the
heating medium comprises hydrogen produced in reformer 32. Suitable hydrogen
catalysts that help hydrogen produce heat include platinum or palladium, for example.

Several suitable thermal catalyst arrangements for transferring heat into heat transfer
appendages 46 were described above (see FIGs. 2A and 2F).
FIGs. 4A and 4B illustrate two systems 400 and 420 that transport a heating
medium from the fuel processor to the fuel cell. The present invention may flexibly
employ heating from fuel processor 15 to fuel cell 20 for improving efficiency of the
fuel cell system. For example, a heating medium may be passed over one or more
appendages 46 during start up of fuel cell 20, or during periods of electrical
generation inactivity when fuel cell 20 is cooling from elevated temperatures
associated with operation.
FIG. 5 illustrates a process flow 500 for generating electrical energy in a fuel
cell that receives hydrogen from a fuel processor in accordance with one embodiment
of the present invention. The fuel processor is configured to process a fuel source to
produce the hydrogen and comprises a burner and a reformer.
Process flow 500 begins by providing the fuel source to the fuel processor
(502). Supply from fuel storage 16 is described above with respect to FIGs. 1A and
IB. When the fuel processor comprises a catalytic burner, the fuel source is supplied
to both the reformer and burner and is used in the burner to generate heat. A catalyst
in the reformer receives heat from the burner and reforms the fuel source to produce
hydrogen.
Process flow 500 then transports a heating medium from the fuel processor to
the fuel cell when a component in the fuel cell has a temperature that is less than a
threshold temperature or when electrical energy output by the fuel cell includes less
than an electrical threshold (504). Electrical energy output by the fuel cell is typically
dc power characterized by a dc voltage and current. The electrical threshold then
refers to a desired electrical output for the fuel cell. For example, if the fuel cell
electrical output drops below 0.54 Volts per cell, then load from the fuel cell may be
turned off and the heating medium transported from the fuel processor to the fuel cell.
The electrical threshold may be represented as a desired output according to a
polarization curve for the fuel cell, which is stored in software available to the
controller of the fuel cell system. The polarization curve represents acceptable
electrical energy output for the fuel cell.

For temperature monitoring, the fuel cell component refers to a portion of the
fuel cell whose temperature affects fuel cell performance. The threshold temperature
refers to a desired temperature to begin external heating of the component. For a
functional component of the fuel cell, the threshold temperature may relate to a
required temperature for the component to contribute to electrical energy generation.
Operating temperatures in the MEA 62 and its constituent parts greater than 190
degrees Celsius are common. An MEA 62 comprising a Celtec 1000 electrolyte from
PEMEAS USA AG mentioned above may require operating temperatures greater than
100 degrees Celsius. The component may alternatively comprise a bi-polar plate, a
gas diffusion layer, a membrane, or any other component mentioned above with
respect to fuel cell 20. The threshold temperature may also vary based on the
component being sensed. Detecting temperature of a bi-polar plate on an external
surface of the fuel cell stack allows the temperature sensor to remain outside the
stack. In this case, the threshold temperature may accommodate the difference in
temperature between an outside portion of the plate where the sensor attaches and an
inside portion proximate to the MEA. Temperature variation in a single plate may
range from 2 to 5 degrees Celsius for example. In general, the threshold temperature
may vary between about 50 degrees Celsius and about 1000 degrees Celsius for some
fuel cell components.
In one embodiment, the heating medium is transported to the fuel cell during a
start-up period before the fuel cell begins generating electrical energy, e.g., in
response to a request for electrical energy. Heating a fuel cell in this manner allows
fuel cell component operating temperatures to be reached sooner and expedites warm-
up time needed when initially turning on fuel cell 20.
hi another embodiment, the heating medium is transported from the fuel
processor to the fuel cell during a period of non-activity in which the fuel cell does
not produce electrical energy and the component cools (502). Since many fuel cells
require elevated temperatures for operation and the electrical energy generating
process is exothermic, the fuel cell usually does not require external heating during
electrical energy generation. However, when electrical energy generation ceases for
an extended time and the component drops below a threshold operating temperature,
the heating medium may then be transported from the fuel processor to regain the
operating temperature and resume electrical energy generation. This permits

operating temperatures in a fuel cell to be maintained when electrical energy is not
being generated by the fuel cell.
The heating medium then heats a portion of the fuel cell (506). The heating
medium may comprise heated exhaust (including air, combustion products and
unused methanol) from a burner or heated exhaust from a reformer (including air,
reforming reactants and reforming products such as hydrogen). Heating may also
employ catalytic combustion in the fuel cell. During fuel cell system start-up, the
reformer may not yet have reached its operating temperature and the exhaust/heating
medium may comprise a high concentration of CO and un-processed fuel (also
referred to as 'dirty hydrogen') that is unsuitable for use in a fuel cell. The hydrogen
may be catalytically combusted to generate heat in a portion of the fuel cell
responsible for heat generation. Suitable examples of heat transfer appendage
techniques to heat a fuel cell and its internal components with the heating medium are
described above.
Process flow 500 detects electrical output of the fuel cell and/or temperature
for the component (510) before transportation of the heating medium begins, and
afterwards. Logic implemented by a controller then compares the detected parameter
with stored values for either threshold. For detecting current and voltage, the
controller logic compares the measured amount with a stored polarization curve. If
the measured voltage or current is output by the fuel cell is about equal to or greater
than an electrical threshold, or a shift in the polarization curve has occurred, then flow
of the heating medium may begin, and in some cases, electrical energy generation
may cease. The component temperature may similarly be read and compared with
stored values.
"When the component temperature drops below the threshold temperature or
the electrical output returns to an unacceptable condition, then flow of the heating
medium may stop, e.g., using a valve between the fuel processor and fuel cell.
Similarly, if the component temperature subsequently rises above the threshold
temperature, then flow of the heating medium may again resume. Thus, when needed,
process flow 500 transports hydrogen from the fuel processor to the fuel cell (508).
Electrical energy is generated (512) in the fuel cell when the temperature of the
component is about equal to or greater than the threshold temperature or when

electrical energy output by the fuel cell is about equal to or greater than an electrical
threshold.
Efficient systems and methods of the present invention may also transport
hydrogen in the fuel cell system to burner 30 in fuel processor 15. A catalyst in the
burner then reacts with the hydrogen to produce heat in the burner. The hydrogen
may come from the anode exhaust of fuel cell 20 and/or from the reformer 32
exhaust.
FIG. 6 illustrates a fuel system 440 that routes unused hydrogen from fuel cell
20 back to burner 30 in accordance with one embodiment of the present invention.
Burner 30 includes a thermal catalyst that reacts with the unused hydrogen to produce
heat.
Fuel system 440 comprises plumbing that is configured to transport hydrogen
to burner 30. Line 51 is configured to transmit unused hydrogen from fuel cell 20 to
burner 30 of fuel processor 15. For system 440, burner 30 includes two inlets: an inlet
55 configured to receive the hydrogen fuel source 17 and an inlet 53 configured to
receive the hydrogen from line 51. Anode gas collection channels, which distribute
hydrogen provided by fuel processor 15 to each membrane electrode assembly layer,
collect and exhaust the unused hydrogen to a hydrogen exhaust manifold (see FIGs.
2A-2F), which delivers the hydrogen to line 51. In one embodiment, gaseous delivery
in line 51 back to fuel processor 15 relies on pressure at the exhaust of the anode gas
distribution channels, e.g., in the anode exhaust manifold. In another embodiment, an
anode recycling pump or fan is added to line 51 to pressurize line 51 and return
unused hydrogen back to fuel processor 15. A fan may also pressurize line 39 to
deliver the hydrogen from an outlet of fuel processor 15 to an anode inlet of fuel cell
20, which also pressurizes flow of hydrogen in line 51.
Since hydrogen consumption within fuel cell 20 is often incomplete and the
anode exhaust often includes unused hydrogen, re-routing the anode exhaust to burner
30 allows fuel cell system 10 to capitalize on unused hydrogen in fuel cell 20 and
increase hydrogen usage and efficiency in system 10.
Line 442 is configured to transmit hydrogen output by reformer 32 to burner
30 of fuel processor 15. Before a reformer reaches its operating temperature upon
system start from a cool temperature or rest state, imperfect hydrogen generation at

low temperatures may lead to reformer output that is unsuitable for use in a fuel cell.
In situations where the reformer output is unsuitable, fuel system 440 re-routes
hydrogen and reformer exhaust to burner 30 via line 442. Burner 30 catalytically uses
the hydrogen to produce heat. The heat may be provided to the reformer to expedite
warm up time for fuel processor 15 and fuel cell system 440.
Fuel cell system 440 provides flexibility to use different fuels in a catalytic
burner 30. For example, if fuel cell 20 can reliably and efficiently consume over 90%
of the hydrogen in the anode stream, then there may not be sufficient hydrogen to
maintain reformer and boiler operating temperatures in fuel processor 15. Under this
circumstance, methanol supply is increased to produce additional heat to maintain the
reformer and boiler temperatures.
FIG. 8 illustrates a schematic operation for a fuel cell system 460 in
accordance with another specific embodiment of the present invention. Burner 30 is
configured to receive oxygen from an oxygen exhaust included in fuel cell 20.
Cathode gas collection channels, which distribute oxygen and air from the ambient
room to each membrane electrode assembly layer, collect and exhaust any unused
oxygen in fuel cell 20. Line 466 receives unused oxygen from an exhaust manifold,
which collects oxygen from each cathode gas collection channel. Line 466 transports
the oxygen to an inlet 464 of burner 30. Since oxygen consumption within fuel cell 20
is often incomplete and the cathode exhaust includes unused oxygen, re-routing the
cathode exhaust to burner 30 allows fuel cell system 10 to capitalize on unused
oxygen in fuel cell 20 and increase oxygen usage and efficiency in system 10. Fuel
cell 20 also heats the oxygen before burner 30 receives the oxygen. Oxygen in the air
provided to burner 30 is consumed as part of the combustion process. Heat generated
in the burner 30 will heat cool incoming air, depending on the temperature of the air.
This heat loss to incoming cool air reduces the heating efficiency of burner 30, and
typically results in a greater consumption of methanol. To increase the heating
efficiency of burner 30, the present invention heats the incoming air in fuel cell 20 so
less heat generated in the burner passes into the incoming air. In other words, fuel cell
20 allows pre-heats air before reaching the burner, thus increasing efficiency of
system 460.

Fuel cell system 460 also transports unused hydrogen from the anode of fuel
cell 20 back to the burner of fuel processor 15 for catalytic combustion and
generation of heat. Fuel cell system 460 also employs an electric heater 462 for
heating reformer 32 with electrical energy.
5. ELECTRONICS DEVICE IMPLEMENTATION
i
FIG. 9 shows a schematic illustration of a system 200 for producing electrical
energy in a portable electronics device 202 in accordance with one embodiment of the
present invention. System 200 comprises fuel processor 15 and fuel cell 20 included
within an electronics device 202 and a hydrogen fuel source storage device 16
coupled to electronics device 202 via connector 104 and mating connector 140.
In one embodiment, fuel processor 15 and fuel cell 20 are incorporated into
electronics device 202 (within its volume and outer housing) as an integral module,
and storage device 16 is a removable device. Fuel cell powered laptop computers 202
may comprise slightly modified existing products, with fuel processor 15 and fuel cell
20 and related system components fitted generally into the space provided for a
battery pack. Mating connector 140 is included in this allocated space for connection
to a removable storage device 16. Storage device 16 mechanically interfaces with
electronics device 202. In one embodiment, connectors 104 and 140 provide
sufficient mechanical force to maintain position between the storage device 16 and
electronics device 202. In another embodiment, electronics device 202 includes a
mechanical slot that storage device 16 fits and slides into.
When connector 104 and mating connector 140 interface, fuel cell system
controller 214 digitally communicates with memory 106 using link 217 for bi-
directional communication therebetween. In another embodiment, controller 214 uses
a wireless interrogator to communicate with an RFID antennae and memory 206
included in storage device 16. Controller 214 may read any information stored in
memory 206 such as a fuel type stored in the storage device 16, a model number for
storage device 16, a volume capacity for bladder 205 or storage device 16, a number
of refills provided to storage device 16, the last refill date, the refilling service
provider, and a current volume for the storage device. Controller 214 estimates the
remaining power in storage device 16 by comparing the fuel source 17 level since last

use or refill against a consumption rate for a particular laptop computer. Controller
214 may also write transient information to memory 106, such as an updated volume
for the storage device. The controller 214 communicates with a main controller 210
for computer 202 and computer memory 218 via communications bus 212. Computer
memory 218 may store instructions for the control of fuel system 10 such as read and
write protocol and instructions for communication with a digital memory 106.
Power management 219 controls power provision by fuel cell system 10 and
electrochemical battery 222. Thus, power management 219 may inform controller
214 how much power is needed for laptop computer 22 operation and controller 214
responds by sending signals to fuel cell 20, fuel processor 15 and a pump that draws
fuel from storage device 16 to alter fuel cell power production accordingly. If fuel
cell system 10 runs out of fuel source 17, then power management 219 switches to
electrical power provision from battery 222.
System 200 may also be configured for 'hot swappable' capability. Hot
swapping of storage device 16 refers to removing storage device 16 from a fuel
processor or electronics device 202 it provides hydrogen fuel source 17 to, without
shutting down the receiving device or without compromising hydrogen fuel source
provision to the receiving device for a limited time. A hot swappable system implies
fuel source provision when connector 104 and mating connector 140 are separated.
Further description of hot swappable fuel cell systems suitable for use with the
present invention are described in commonly owned co-pending patent application
entitled "Portable Fuel Cartridge for Fuel Cells" naming Ian Kaye as inventor and
filed on the same day as this patent application, which is incorporated by reference
for all purposes.
Main controller 210 is preferably a commercially available microprocessor
such as one of the Intel (including Pentium™) or Motorola family of chips, a reduced
instruction set computer (RISC) chip such as the PowerPC™ microprocessor
available from Motorola, Inc, or any other suitable processor. Memory 216 may
comprise some form of mass storage but can be eliminated by providing a sufficient
. amount of RAM to store user application programs and data. Memory 216 may also
contain the basic operating system for the computer system 350. It is generally
desirable to have some type of long term mass storage such as a commercially

available hard disk drive, nonvolatile memory such as flash memory, battery backed
RAM, PC-data cards, or the like. Regardless of computer system configuration, it
may employ one or more memories or memory modules configured to store program
instructions for controlling fuel cell and thermal systems described herein. Such
memory or memories may also be configured to store data structures, control
programs, or other specific non-program information described herein.
In addition, although the present invention is primarily described with respect
to fuel cell systems and methods operating on a fuel cell system, many of the methods
and techniques described constitute system controls and will comprise digital control
applied by control logic that implements instructions from stored software. The
control logic includes any combination of hardware and software needed for control
within system 10. For example, the control logic may include instructions stored in
memory 216 that are executed by main controller 210. The stored instructions may
correspond to any methods or elements explained in the process flows described
herein. Input/output logic may be employed to facilitate communication between
main controller 210 and components of fuel system 10. In one embodiment, the
control logic is configured to regulate heat transfer or temperature in system 10 by
controlling the routing of liquids and gases between fuel cell 20, fuel processor 15
and electronics device 202. In a specific embodiment, the control logic is configured
to start fuel system 10. This includes control logic configured to start a fuel processor
including a reformer and a burner that provides heat to the reformer. In another
specific embodiment, the control logic is configured to shut down a fuel cell system
comprising a fuel cell that received hydrogen from a fuel processor including a
reformer and a burner that provided heat to the reformer. In another specific
embodiment, the control logic is configured to regulate the transport of a heating
medium from the fuel processor to the fuel cell when electrical energy output by the
fuel cell includes less than an electrical threshold or when temperature of a
component in the fuel cell is less than a temperature threshold. In this case, memory
216 may include one or more polarization curves that help determine when to
transport of the heating medium.

6. FUEL SYSTEM START UP
Another aspect of the present invention relates to methods for improving fuel
cell system start up. Fuel cell system components often require elevated temperatures
before electrical energy production occurs. Techniques described herein expedite the
time needed for fuel cell system start up.
Many fuel processors avoid providing a liquid fuel source to a burner or
reformer catalyst. During normal operation, a boiler vaporizes the fuel source before
receipt by the burner or reformer. However, a boiler may not have, sufficient heat
during start-up to heat the fuel source. In this case, the present invention heats and
vaporizes a fuel source using electrically generated heat that maybe readily turned on
during fuel processor and system start-up.
FIG. 10A illustrates a system for heating a fuel source before catalytic heat
generation within burner 30 in accordance with one embodiment of the present
invention. As shown, the system includes a fuel processor 15 and an electric heater
806. The fuel processor 15 comprises a reformer 32, burner 30 and boiler 34, which
were described above with respect to FIG. 1 A. Reformer 32 comprises a catalyst 804
that facilitates the production of hydrogen. Catalyst 804 reacts with methanol 17 and
facilitates the production of hydrogen gas. In one embodiment, catalyst 804
comprises pellets packed to form a porous bed or otherwise suitably filled into the
volume of the reformer chamber.
Burner 30 comprises a catalyst bed 808 that helps a burner fuel passed
through the burner chamber generate heat. In one embodiment, methanol produces
heat in burner 30 and catalyst 808 facilitates methanol-based production of heat. In
another embodiment, waste hydrogen from fuel cell 20 produces heat in the presence
of catalyst 808. Suitable burner catalysts 808 may include platinum or palladium
coated onto alumina pellets for example.
Electric heater 806 is configured to heat burner 30 or the fuel source 17
provided to burner 30. As shown, electrical heater 806 is disposed within the burner
chamber 810 and intercepts the fuel source 17 before the fuel source passes over
catalyst bed 808. In this case, a portion of chamber 810 is reserved for electrical
heater 806 and heating of fuel source 17. A small gap 816 is left between heater 806
and catalyst 808 to allow room for the fuel source 17 to heat, vaporize and spread

within the burner chamber. Gap 816 sizes from about 2 millimeters to about 5
millimeters are suitable for many small fuel processors.
Electrical heaters suitable for use in fuel processor 15 may employ a resistive
heating element. A rechargeable battery, capacitor or other electrical power supply
S20 provides electrical energy to heater 806. In one embodiment, a fuel cell that
receives hydrogen from fuel processor 15 outputs electrical energy to recharge the
capacitor 820. Electric heater 806 may comprise a thin-film platinum, gold, graphite,
nickel, chromium, aluminum, alloy or other base metal that may be deposited and
used for a resistive heater. A model P/N CSS-01110 cartridge heater as provided by
Omega of Stamford, CT is suitable for use as electrical heater 806 in some
embodiments.
Electric heater 806 may also comprise a catalyst disposed on an outside
surface of heater 806 that generates heat in the presence of fuel source 17. Platinum,
for example, may be coated onto the external surface of the heater to interact with
fuel source 17 to generate heat in the presence of the fuel source. The catalytic heat
then increases heat generation and warming of the incoming fuel source 17.
In another embodiment, electrical heater 806 is embedded in the burner
catalyst bed 808 and heats the catalyst bed 808. In this case, an insulating cover is
used to electrically isolate heater 806 from catalyst 808. The insulating cover includes
a high temperature, electrically insulating material, such as a ceramic tube.
Alternatively, electrical heater 806 may be disposed external to burner 30 and in
thermal communication with fuel source supply 27 to heat fuel source 17 before it
enters burner 30. A heat exchanger may be employed to facilitate heat transfer
between supply 27 line and heater 806.
Burner 30 shows a common inlet 812 that receives both fuel source 17 and air
that have been mixed prior to entry into burner chamber 810. In another embodiment,
burner 30 includes two separate and dedicated inlets for fuel source 17 and air,
respectively. The dedicated fuel source inlet may also comprise an atomizing nozzle
to facilitate vaporization of the fuel source.
Thermal communication between burner 30 and reformer 32 also allows heat
generated by electrical heater 806 to heat fuel source 17 entering reformer 32. In
another embodiment, the present invention employ electrical heat to warm a reformer

or reformer catalyst during start-up. FIG. 10C illustrates a system for electrically
heating a reformer 32 in accordance with one embodiment of the present invention.
Reformer comprises an inlet 31a that receives fuel source 17, catalyst 804 and
an outlet 31b that outputs hydrogen gas. In one embodiment, reformer 32 is sized for
portable applications and comprises a reformer chamber having a volume greater than
about 0.1 cubic centimeters and less than about 50 cubic centimeters. Reformer 32
volumes between about 0.5 cubic centimeters and about 2 cubic centimeters are
suitable for laptop computer applications. Further description of annular fuel
processors suitable for use with the present invention are included in commonly
owned co-pending patent application entitled "Annular Fuel Processor and Methods"
naming Ian Kaye as inventor and filed on the same day as this patent application,
which is incorporated by reference for all purposes.
Electric heater 806 is configured to heat reformer 32. As shown, electric
heater 806 is embedded in the reformer 32 catalyst 804 bed. An insulating cover, such
as a ceramic tube, electrically isolates heater 806 from catalyst 804. In this case, the
electric heater 806 applies heat directly into the reforming catalyst 804 so that the
whole fuel processor 15 is not heated at startup. This brings the fuel cell online (even
at reduced power) faster. In addition, disposing the electric heater 806 in thermal
contact with the reformer 32 catalyst minimizes external power requirements from a
battery or capacitor.
Heater 806 heats reformer 32 or catalyst 804 during fuel processor start-up. A
temperature sensor 818 detects the temperature of the reformer catalyst bed or a wall
of reformer 32. When the catalyst 804 reaches a desired temperature for example,
heater 806 is turned off. Burner 30 comprises an inlet 33 that receives the fuel source
17. A catalyst bed 808 in burner 30 heats reformer 32 after electric heater 806 is
turned off. Electric heater 806 readily thus heats up reformer 32 and allows it to reach
operating temperature quickly, with assistance from burner 30 if needed and a
minimal amount of electrical heat input.
An electric heater may also be employed when the fuel processor is
constructed using MEMS technology. In one MEMs design, a reformer comprises
three separate chips: a heater/boiler chip, a reformer/ heater chip and a preferential
oxidizer chip. All three chips may have a glass cover and share common manifolds

that direct process gasses to the correct chip. The heater/boiler chip has a thin film
heater deposited in the flow channels, suitable for use during startup. The
heater/reformer and preferential oxidizer chips include MEMS deposited temperature
sensors either on the flow channels, or on the glass cover. Deposition of thin film
heaters and sensors is well understood to those of skill in MEMS technology.
FIG. 10B illustrates a process flow 820 for starting up a fuel processor in
accordance with one embodiment of the present invention. The fuel processor
includes a reformer and a burner that provides heat to the reformer. A fuel cell
receives hydrogen produced by the fuel processor.
Process flow 820 begins by generating heat using an electrical heater that is
configured to heat the burner or a fuel source provided to the burner (822). The
electrical heater may also be configured to heat the reformer or a fuel source provided
to the reformer. The heat may vaporize the fuel source. The electrical heater generates
heat for a set duration or until a particular operating condition is reached. In one
embodiment, the electrical heater generates heat for at least ten seconds before the
fuel source is supplied to the burner. Some fuel processors may be heated for 30
seconds, up to a minute, or even longer. A threshold start temperature may also be
used to determine the heating duration. A temperature sensitive catalyst, burner or
reformer may require that the electrical heater generate heat until the catalyst, burner
or reformer reaches a threshold start temperature. Some burner catalysts include a
threshold start temperature above 60. degrees Celsius. Some reformer catalysts
include a threshold start temperature above 100 degrees Celsius. Alternatively, the
electrical heater generates heat until the reformer walls reach 150 degrees Celsius or
some other operating temperature. In one embodiment, air and the fuel source mix
before the fuel source reaches the burner and electrical heater. In this case, the
electrical heater maybe disposed outside the burner to pre-heat the fuel source before
entering the burner.
Process flow 820 then supplies the fuel source to the burner (822). Typically,
a pump moves the fuel source and turns on via a system controller. The controller
may also turn on a fan that provides air to the burner. A catalyst in the burner then
catalytically generates heat in the burner to heat the reformer (824). The fuel source
enters the burner before the reformer reaches its operating temperature. If the burner

catalyst requires a lower operating temperature than the reformer catalyst, catalytic
heat generation in the burner may be used to continue heating the reformer - and the
electric heater is turned off after the fuel source is supplied to the burner. If the
reformer has not yet reached its operating temperature, the reformer exhaust may
comprise a high concentration of CO and un-processed fuel ('dirty hydrogen') that is
unsuitable for use in a fuel cell. As described above, the hydrogen may be routed
from a reformer outlet to a burner inlet to react with a thermal catalyst in the burner
and generate additional heat in the burner to expedite the time needed for the reformer
to reach operating temperature.
The fuel source is then supplying to the reformer (826). A catalyst in the
reformer then catalytically generates hydrogen (828). Plumbing transports the
hydrogen to a fuel cell that generates electricity using the hydrogen. In one
embodiment, the electrical heater receives energy from a capacitor that is recharged
by the fuel cell after the fuel cell system gains a steady operating status. The capacitor
or rechargeable battery may also be recharged during system start-up when then fuel
cell is at limited capacity, e.g., about 5-15% rated power. At this point, the fuel cell
power is enough to operate the electric heater, and the startup capacitor or
rechargeable battery can be turned off or recharged.
7. FUEL SYSTEM SHUTDOWN
The present invention also includes methods for shutting down a fuel cell
system. FIG. 7 illustrates a process flow 600 for shutting down a fuel cell system
comprising a fuel cell that received hydrogen from a fuel processor in accordance
with one embodiment of the present invention. The fuel processor includes a reformer
and a burner that provided heat to the reformer. Process flow 600 is particularly
useful to expunge any liquids in the fuel cell system, including those present when the
system is initially shut down and those that accumulate via condensation as the
system cools.
Process flow 600 begins by stopping electrical energy generation in the fuel
cell (602). This may occur electrically by varying the charge in the anode and/or
cathode. Hydrogen supply to the fuel cell may also be ceased, e.g., using a valve on a
line that transports hydrogen to the fuel cell.

Process flow 600 then discontinues a supply of the fuel source to the reformer.
For system 10 of FIG. 1B, valve 23 disposed on line 29 between fuel tank 14 and
reformer 32 cuts fuel source provision to the reformer. Cutting power to a pump may
also be used to discontinue the fuel supply. Heat is then generated in the burner to
heat to the reformer after discontinuing the supply of the fuel source to the reformer
(506). In some cases, heat generation in the burner may continue for greater than
about 30 seconds after discontinuing the supply of the fuel source to the reformer.
Alternatively, heat generation in the burner may continue unless the fuel cell load has
dropped below 10% rated power for a few minutes or unless a polarization curve for
the fuel cell has lowered, e.g., the voltage of the fuel cell has reduced significantly for
a given current.
Heat generation in the burner is then discontinued (508). For an electric
burner, this may be done via an electrical switch or digital control. For a catalytic
burner such as that used in system 10 of FIG. 1B, the burner then includes an inlet to
receive the fuel source from a supply of the fuel source and the burner catalytically
generates heat using the fuel source. A valve disposed on a line 27 between a fuel
tank 14 and reformer 32 may cut fuel supply to the reformer. The burner is then
flushed with air (510). Air supply may continue for greater than about 60 seconds
after discontinuing the supply of the fuel source to the reformer. Alternatively, air
supply may continue until the burner temperature reaches a threshold cooling
temperature, such as 80 degrees Celsius The above steps sufficiently shut down the
reformer and ensure no fuel is left in the reformer chamber or burner.
The present invention may also shut down the fuel cell. To do so, air is
provided to a cathode gas distribution system in the fuel cell after discontinuing
hydrogen supply to the fuel cell. Powering a fan that pressurizes air supply to the
cathode gas distribution system may do this. The fuel cell may also be cooled. For
system 10 of FIG. 1B, fan 37 may be turned on to move cooling air across the heat
transfer appendages 46 until a desired shut-down temperature is reached. Both fans
may run until the fuel cell is cooled to a desired temperature and moisture has been
removed by the air supply from the cathode gas distribution system.

8. CONCLUSION
While this invention has been described in terms of several preferred
embodiments, there are alterations, permutations, and equivalents that fall within the
scope of this invention which have been omitted for brevity's sake. For example,
although the present invention has been described with respect to methods operating
on a fuel cell system, many of the methods and techniques described constitute
system controls and will comprise digital control applied by a processor that
implements instructions from stored software. While not described in detail, such
digital control of a mechanical system is well known to one of skill in the art and the
present invention may thus relate to instructions stored in software capable of
carrying out methods described herein. It is therefore intended that the scope of the
invention should be determined with reference to the appended claims.

WE CLAIM:
1. A fuel cell system for producing electrical energy, the fuel cell system comprising:
a fuel processor that comprises
a reformer configured to receive a fuel source, configured to output hydrogen,
and including a catalyst that facilitates the production of hydrogen;
a burner configured to provide heat to the reformer;
a fuel cell comprising a fuel cell stack configured to produce electrical energy using
hydrogen output by the fuel processor, the fuel cell stack including a bi-polar plate having I)
a single substrate from a first face to a second face, ii) a first channel field disposed on the
first face and having a first set of channels formed into the first face, iii) a second channel
field disposed on the second face and having a second set of channels formed into the second
face, where the single substrate is configured to maintain separation of gases between the
first set of channels and the second set of channels, and iv) a heat transfer appendage that a)
includes a portion arranged external to the fuel cell stack and b) is in conductive thermal
communication with an internal portion of the fuel cell stack; and
plumbing configured to transport a heating medium from the fuel processor to the
fuel cell;
wherein the bi-polar plate is configured to receive heat provided to the fuel cell using
the heating medium at the externally arranged heat transfer appendage and configured to
conduct the heat to the internal portion of the fuel cell stack.
2. The fuel cell system as claimed in claim 1 wherein the plumbing is configured to
transport the heating medium from the fuel processor to the heat transfer appendage.
3. The fuel cell system as claimed in claim 2 wherein the heating medium comprises the
fuel source after the fuel source has been vaporized.

4. The fuel cell system of as claimed in claim 3 wherein the plumbing comprises a line
that is configured to transport the heating medium from an exhaust of the burner to the fuel
cell.
5. The fuel cell system of as claimed in claim 1 comprising a thermal catalyst disposed
in contact with or in proximity to the heat transfer appendage and that facilitates heat
generation with exposure to the heating medium.
6. The fuel cell system as claimed in claim 5 wherein the thermal catalyst is disposed on
the heat transfer appendage.
7. The fuel cell system as claimed in claim 5 wherein the thermal catalyst comprises
platinum.
8. The fuel cell system as claimed in claim 5 comprising a bulkhead that contains the
thermal catalyst, wherein the bulkhead is attached to the heat transfer appendage.
9. The fuel cell system of as claimed in claim 1 wherein the plumbing comprises a line
that is configured to transport the heating medium from an exhaust of the reformer to the fuel
cell.
10. The fuel cell system as claimed in claim 1 wherein the heating medium comprises
hydrogen produced in the reformer.

11. The fuel cell system as claimed in claim 1 wherein the heating medium is greater than
about 100 degrees Celsius when the heating medium leaves the fuel processor.
12. The fuel cell system of as claimed in claim 1 wherein the heating medium is greater
than about 200 degrees Celsius when the heating medium leaves the fuel processor.
13. The fuel cell system as claimed in claim 1 comprising at least one temperature sensor
that detects a temperature for a component in the fuel processor.
14. The fuel cell system as claimed in claim 1 comprising at least one sensor mat detects
a temperature for a component in the fuel cell.
15. The fuel cell system as claimed in claim 1 wherein the plumbing is configured to
transport hydrogen to the burner.
16. The fuel cell system as claimed in claim 15 wherein the plumbing is configured to
receive hydrogen produced in the reformer and transport the hydrogen to the burner.
17. The fuel cell system as claimed in claim 15 wherein the plumbing is configured to
receive hydrogen exhausted from the fuel cell and transport the hydrogen to the burner.
18. The fuel cell system as claimed in claim 17 wherein the plumbing is configured to
receive hydrogen exhausted from an anode gas collection system in the fuel cell.

19. The fuel cell system as claimed in claim 15 wherein the burner includes an inlet
configured to receive the fuel source.
20. The fuel cell system as claimed in claim 19 wherein the fuel cell is configured to
output less than 200 watts of power.
21. The fuel cell system as claimed in claim 1 wherein the plumbing is configured to
transport oxygen from the fuel cell to the fuel processor.
22. The fuel cell system as claimed in claim 21 wherein the plumbing is configured to
receive oxygen exhausted from a cathode gas collection system in the fuel cell.
23. The fuel cell system as claimed in claim 21 wherein the fuel processor comprises a
dewar configured to receive the oxygen and configured to provide the oxygen to the burner.
24. The fuel cell system as claimed in claim 23 wherein the dewar is configured to heat
the oxygen before providing the oxygen to the burner.
25. The fuel cell system as claimed in claim 23 wherein the fuel cell is configured to
output less than 200 watts of power.
26. The fuel cell system as claimed in claim 1 wherein the plumbing is configured to
transport a heating medium or a cooling medium between the fuel processor and the fuel cell.

27. The fuel cell system as claimed in claim 26 wherein the plumbing is configured to
transport the heating medium from the fuel processor to the heat transfer appendage.
28. The fuel cell system as claimed in claim 26 comprising a thermal catalyst disposed in
contact with or in proximity to the heat transfer appendage and that facilitates heat generation
with exposure to the heating medium.
29. The fuel cell system as claimed in claim 26 wherein the plumbing is configured to
transport the heating medium from the fuel cell to the fuel processor.
30. The fuel cell system as claimed in claim 1 comprising control logic configured to
regulate heat transfer or temperature for one or more components within the fuel cell system.
31. The system as claimed in claim 30 wherein the control logic is configured to generate
heat in the burner to heat to the reformer after discontinuing the supply of the fuel source to
the reformer.
32. The system as claimed in claim 31 wherein the control logic is configured to
discontinue heat generation in the burner.
33. The system as claimed in claim 32 wherein the control logic is configured to flush the
burner with air.
Described herein are fuel cell systems (10, 400, 420, 420, 460) and methods of using
fuel cell systems. The systems include a fuel cell (20) that generates electrical energy using
hydrogen and a fuel processor (15) that produces hydrogen from a fuel source (16). The fuel
processor (15) includes a reformer (32) and a burner (30) that heats the reformer (32). One
heat efficient fuel cell system described herein heats internal portions of a fuel cell (20) using
a heating medium from a fuel processor (15). The heating medium may comprise gases
exhausted at high temperatures from the fuel processor (15), which are then transported to
the fuel cell (20). The heating medium may also include a gas that reacts catalytically in the
fuel cell (20) to produce heat. Systems and methods for expediting fuel cell system start up
are provided. Methods for shutting down a fuel cell system are also described that reduce the
amount of moisture and gases in the reformer (32) and in one or more fuel cell components.
One hydrogen efficient fuel cell system described herein transports hydrogen to an inlet of a
burner (30). The hydrogen may comprise unused hydrogen from a fuel cell (20) and/or
hydrogen produced in a reformer (32). The burner (30) comprises a catalyst that facilitates
production of heat in the presence of the hydrogen.

Documents:

00013-kolnp-2006-abstract.pdf

00013-kolnp-2006-claims.pdf

00013-kolnp-2006-description complete.pdf

00013-kolnp-2006-drawings.pdf

00013-kolnp-2006-form 1.pdf

00013-kolnp-2006-form 3.pdf

00013-kolnp-2006-form 5.pdf

00013-kolnp-2006-international publication.pdf

00013-kolnp-2006-international search authority.pdf

00013-kolnp-2006-priority document.pdf

13-kolnp-2006-assignment.pdf

13-kolnp-2006-correspondence-1.1..pdf

13-KOLNP-2006-CORRESPONDENCE.pdf

13-kolnp-2006-examination report.pdf

13-kolnp-2006-form 18.pdf

13-kolnp-2006-form 3.pdf

13-kolnp-2006-form 5.pdf

13-kolnp-2006-gpa.pdf

13-kolnp-2006-granted-abstract.pdf

13-kolnp-2006-granted-claims.pdf

13-kolnp-2006-granted-description (complete).pdf

13-kolnp-2006-granted-drawings.pdf

13-kolnp-2006-granted-form 1.pdf

abstract-00013-kolnp-2006.jpg


Patent Number 246022
Indian Patent Application Number 13/KOLNP/2006
PG Journal Number 06/2011
Publication Date 11-Feb-2011
Grant Date 09-Feb-2011
Date of Filing 02-Jan-2006
Name of Patentee ULTRACELL CORPORATION
Applicant Address 399 LINDBERGH AVENUE, LIVERMORE, CALIFORNIA 94551, UNITED STATES OF AMERICA
Inventors:
# Inventor's Name Inventor's Address
1 KAYE IAN W 1307 CHATEAU COMMAN, LIVERMORE, CALIFORNIA 94550, UNITED STATES OF AMERICA
2 TUCKER GERRY 4206 DUNDALK COURT, PLEASANTON, CA 94566, UNITED STATES OF AMERICA
PCT International Classification Number H01M 08/04
PCT International Application Number PCT/US2004/020517
PCT International Filing date 2004-06-25
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/482,981 2003-06-27 U.S.A.
2 60/482,996 2003-06-27 U.S.A.
3 60/483,416 2003-06-27 U.S.A.