Title of Invention

CERAMIC HONEYCOMB BASED ENERGY EFFICIENT AIR HEATER

Abstract

A ceramic honeycomb based energy efficient air heater includes a ceramic honeycomb monolithic structure with a plurality of parallel holes with square, rectangular, circular, hexagonal or any other geometrical cross section. These holes behave as the channels for passage of air when air is blown or allowed to pass through them. An electrical resistance-heating element is woven through these channels in such a fashion that the heating element passes through any channel only once. A predetermined number of channels are woven with the elements. The two ends of the electrical resistance heating element are terminated to two electrodes which are rigidly fixed in two empty channels. The two electrodes are always positioned on the air inlet side of the honeycomb. When air is blown through the honeycomb and electrical current is supplied to the electrode, the system performs as a very energy efficient hot air unit.

Full Text

This invention relates to an energy efficient air heater. The heater of the present invention is highly efficient in heat transfer, compact in size, quick to start, low thermal mass and reduces heat wastage and hence the present invention is very energy efficient. The heater of this invention is useful in wider areas of applications like domestic, industrial heaters, dryers, hospital room warmers, room heaters, hot air knives and many tailor made needs. Conventional air heaters are normally fabricated with bare coiled wire, wire wound around ceramic rods or wire embedded ceramic beads in tubular metal sheaths over which fins of different kinds are arranged. These air heaters may or may not be provided with other essential components such as thermostats, air generating systems, blowing ducts, outlets etc. Most of such heaters suffer from the draw back of low power utilization as well as low thermal efficiency due to poor coefficient of heat transfer. Considering the high cost of power as well as to achieve higher thermal efficiency it will be advantageous if a heater having improved properties is made available. Such a heater will also reduce heat wastage resulting in energy conservation, which is a very important criterion in the economic development of a country such as India. The main objective of the present invention is, therefore to provide an improved energy efficient air heater which utilizes less power and has higher thermal efficiency , compact in size and has wider applicability . It has been an object of the present invention to provide a sufficiently strong ceramic honeycomb monolith structure with plurality of parallel holes (here -after called channels) with predetermined wall thickness and channel size to insert and weave an electrode in and out of all or some of the holes in a predetermined fashion, there by creating series of parallel channels with nearly parallel woven elements from a single electrode or more. It has also been an object of the present invention to provide a ceramic honeycomb monolithic body with plurality of channels of circular, square, rectangular, triangular or any other cross section to act as the support structure for the electrical resistance heating element woven through its channels and the channels in turn to act as passages for air when air is blown through them or allowed to pass through them. It has also been an objective of the present invention to provide an efficient air heater employing ceramic honeycomb monolithic structures with plurality of parallel holes, made of cordierite or steatite or alumina or alumina silica based formulations. Yet another objective of the invention is to reduce the size of the heater to more than 30% of the conventional air heater of similar heat output and productive heat requirements there by allowing better space management. Still another important objective of the present invention is to provide a heating unit, which minimizes start-up times due to its low thermal mass owing to its high coefficient of heat transfer there-by improving the productivity, reduce down times and improves the over all utilization of power. Yet another objective of the present invention is to provide a heater with an electrical resistance-heating element woven in such a fashion that all its windings are well insulated from one another due to the ceramic honeycomb channel walls separating them and with no scope of short-circuiting with the outer structure. We have observed that ceramic honeycomb monolithic units fabricated from materials such as cordierite or steatite can be used in the manufacture of heaters. We have further observed that configurations such as circular/ triangular / rectangular / square /hexagonal and any other shaped honeycomb monolithic units fabricated from the above said materials when used in the manufacture of heaters, and the electrical resistance heating element is woven through the channels of the honeycomb, the resulting heaters when used in generation of hot air are energy efficient. Summary of the invention In its very simplest of forms, the present invention relates to an improved energy efficient air heater employing a ceramic honeycomb monolithic body with plurality of parallel holes of circular, square, rectangular, triangular, hexagonal or any other geometric shape of cross section forming the element support channels and when the electrical resistance heating element is woven through these channels in such a fashion that the said heating element passes through each channel only once and there is an annular space in between the said heating element and the said channel walls and these channels also serve as passages for air when air is blown through or allowed to pass through these channels. The electrical resistance heating element may be round, flat, rectangular or any other cross section and is of predetermined length. The said heating element is inserted and woven through the channels of the honeycomb monolithic structure in such a fashion that the said heating element passes only once through each of the channels in a predetermined fashion. The electrode element may be wound through the channels as a straight wire or as zigzag bent wire or alternately as coiled wire of predetermined coil diameter. Both the ends of the electrical resistance-heating element are extending out of the channels from one end of the honeycomb to be properly terminated for power connection. Two electrodes of appropriate length are inserted in to two empty channels of the honeycomb and fixed rigidly in those channels by means of suitable ceramic cement. Each end of the electrical resistance heating element extending out of the ceramic honeycomb body is securely and rigidly terminated to each of the fixed electrodes respectively. The heater is canned in an appropriate container in such a fashion that the rigidly fixed electrodes are always positioned on the air inlet end of the main body. The electrodes are terminated out side the heater body to a connector. When power is supplied to the electrode and air is blown through the channels of the honeycomb, heat is generated in the electrical resistance heating element .The air passing through the channels of the honeycomb is in intimate contact with the entire length and surface area of electrode in individual channels thereby creating a most favorable condition for efficient convective heat transfer and provide us with an energy efficient air heating system. The ceramic honeycomb channel walls act as good insulators positioned in-between every two parallel element windings besides supporting the electrode at every winding point thereby providing a stable and strong unit. Not much heat storing is observed in the heater body during the operating period, as air is allowed to pass through all the channels with out preference. As air passes through the channels continuously, almost entire heat generated in the electrical resistance-heating element is transferred. And the resulting air heater is energy efficient and has many distinct advantages over the conventional air heaters. Brief description of the drawings Accordingly we have fabricated an energy efficient air heater with ceramic honeycomb monolithic body '6' made of cordierite, steatite, and alumina- silica based materials. An electrical resistance heating element '5' is woven through the channels in the said manner and terminated at the two electrodes, fixed rigidly in two empty channels of the ceramic honeycomb unit. This ceramic honeycomb unit is in-turn fitted in to the main body ' 1' with provision for air inlet '2' and air outlet '3'. The electrodes are positioned on the air inlet side of the heater. The electrodes are terminated out side the main body to a connector. A diffuser '4' to spread air uniformly is in between the air inlet and the honeycomb body. A thermocouple '7' is provided in some applications. Figure. No .1. Represents the view of the heater in one of its simplest forms Figure No. 2. Represents the general circuit of electrical part of the system. This can vary according to specific needs of the heater Detailed description The ceramic honeycomb monolith body - The external cross sectional shape of the honeycomb may be round, square, elliptical, rectangular, triangular or any other geometrical shape and size to suit the specific need. The internal charmels may be of round, square, rectangular, triangular, hexagonal, or any other geometrical shape and size to suit specific needs. The wall thickness of the channels may vary from 0.2mm to 2.0mm or more as per requirement. The cross sectional open area of the channel can be anywhere from 0.04 sq .mm to 100 sq.mm depending on the requirement of the heater .The total open channel area may be more than 50 % of the total cross sectional area The electrical resistance heating element- The heating element may be of Nichrome, Kanthal, or of any standard resistance material selected on the basis of the heater required. The cross section may be round, flat, and ribbon, rectangular with rounded edges or any other section. The diameter of the heating element may vary from 0 .1 mm to 2 .0 mm or more as the case may be. The number of channels containing the heating element is variable from heater to heater. The manner of distribution of channels with heating element and channels without heating element is dependent on individual application of heater. The Electrodes- The electrodes are of suitable dimensions and are partly embedded rigidly in to two empty channels by means of a suitable ceramic cement and the extended portion of the electrode will act as terminations for the electrical resistance heating element and the electrodes will in turn be terminated outside the main body ' 1' The Main Body - The figure '1' shows a schematic shape of the main body and the main body shape may vary depending on the type and purpose of the heater. It may be fabricated out of any suitable material. The general electrical circuit provided to the heater is shown in fig -2. The thermostat and other accessories of the system like diffuser etc can be incorporated inside the main body of the heater or outside the system as per convenience. The advantages of the heater of the present invention: - 1. The heater is of compact size. 2. 30 % more heat efficiency as compared to conventional heaters. 3. Prolonged life due to special configuration. 4. Minimizes fuel input resulting in economy of operation 5. Easy and economical to fabricate in comparison to PTC heaters and other conductive honeycomb heaters. 6. Affordable by a wider range of end users due to low input and operational costs 7. Safe to use even in some domestic applications. 8. Quick to start due to high co-efficient of heat transfer resulting in improved productivity and reduced downtime 9. Heater ratings can be designed, to the nearest value of calculated power needed, thus ensuring good utilization. We claim 1. An improved energy efficient air heater, comprises of a main body (1) provided with insulation having an inlet (2) and an outlet (3) at two ends respectively. A distributor / diffuser disc (4) placed at the inlet end of the heater for uniform distribution of air, the main body (1) housing at-least a single honeycomb structured monolith unit of appropriate configuration made of cordierite or steatite or alumina or alumina - silica based body with plurality of parallel holes acting as channels for passage of air when air is blown or allowed to pass through them. 2. An improved energy efficient air heater as claimed in claim 1 wherein the said ceramic honeycomb monolithic body with plurality of parallel holes acting as channels will have at-least one electrical resistance heating element, of predetermined cross section and length woven through the honeycomb channels in such a way that the weavings are in general parallel to each other and also parallel to the direction of air flow. 3. An improved energy efficient air heater as claimed in claim 1, wherein said electrical heating element is woven through the channels of the said ceramic honeycomb monolith in such a way, that the finished heater will have the element passing through each channel only once and also in such a way, that air can freely pass through the annular space between the element and the walls of the channel. 4. An improved energy efficient air heater as claimed in claim 1 wherein both the ends of the said electrical resistance heating element are properly terminated to two electrodes which are in-tum fixed rigidly by a suitable ceramic cement in to two empty channels of the said ceramic honeycomb monolith structure, the electrodes are always positioned on the air inlet end of the honeycomb. These electrodes are finally terminated on the outer shell through an insulated port on the heater main body. 5. An improved energy efficient air heater as claimed in claim 1 wherein more than one ceramic honeycomb monolithic structures arranged side by side with in one plane so that air travels parallely and simultaneously through all the ceramic honey comb monolithic structures, conversely the ceramic honeycomb monolithic structures with the heating elements may be arranged in tandem so that outlet air fi-om one honeycomb unit travels through the second honeycomb unit and so on. 6. The ceramic honeycomb heater as claimed in claim '2' wherein the electrical heating element woven in all or some of the channels, the said heating element may be woven as a straight wire, strip, and ribbon or as a zigzag bent form or even as a coil 7. Electrical resistance heating element as claimed in claim.'2', wherein the said element is woven through the channels, and the said element is woven through one channel at a time and forms a bend at the edge of one channel to enter the next channel and so forth while ensuring that during the said weaving operation and bending operations, the said electrical resistance heating element does not get physically worn out or damaged in the process of winding.

Documents:

0030-mas-1999 abstract-duplicate.pdf

0030-mas-1999 abstract.pdf

0030-mas-1999 claims.pdf

0030-mas-1999 correspondence-po.pdf

0030-mas-1999 correspondnece-others.pdf

0030-mas-1999 correspondnece-po.pdf

0030-mas-1999 description(complete)-duplicate.pdf

0030-mas-1999 description(complete).pdf

0030-mas-1999 drawings-duplciate.pdf

0030-mas-1999 drawings.pdf

0030-mas-1999 form-1.pdf

0030-mas-1999 form-19.pdf