Title of Invention

COOLING TOWER ENERGY SAVER

Abstract A Device of COOLING TOWER ENERGY SAVER for saving energy consumed by the fan in a cooling tower operation fitted to a cooling tower having a water in-let, a water out-let and an overhead fan characterized in that the energy saver comprises; (i) Two signal reception means to receive signals from Resistance Temperature Devices (temperature sensors), one being placed at the water out-let which senses the temperature of water therein and the other being placed near the cooling tower which senses the ambient air temperature, which are all connected through sensor cables (ii) A comparing means to compare the signals from both Resistance Temperature Devices (RTDs) and to decide upon; and (iii) A Variable Frequency Drive/Pan Starter to send conditional electric supply to the Fan Motor in such a way that the Fan is switched on/off/speed of the fan varied by which the power consumption is minimized AND a method of Saving Energy spent by the fan(s) in a cooling tower characterized in the stoppage of rotation of fan(s) when the water reaches ambient temperature, restarting the fan(s) when the temperature of water increases above the ambient temperature and regulating the speed of fan(s), as required by means of feedback as received by the Energy Saving Controller from the sensors sensing ambient temperature and water temperature concurrently and as conveyed to the fan motor through the fen starter/Variable frequency drive.
Full Text

This invention basically relates to the field of manufacture of an electronic device for controlling the operation of a fan, used for Cooling the water in a Cooling Tower. This invention relates to the field of energy conservation and also addresses the problem of energy loss taking place rampantly in the industry. This invention is further concerned with electrical and electronic technologies. The invention is a breakthrough after extensive and successful test/trial runs and being cost effective, a big motivator to understand the fundamentals behind the Cooling Tower (CI) and energy consciousness creator among the industrialists, energy auditors, Plant Engineers and Heating, Ventilating and Air-Conditioning (HVAC) Consultants. The invention focuses on sensing climatic variations themselves and saving energy thereby whereas such other currently known devices only work at a preset temperature and such devices cannot sense variations in climatic conditions.
BACKGROUND OP INVENTION WITH REGARD TO THE DRAWBACKS OP KNOWN ART:
BACKGROUND OF INVENTION:
A Cooling tower (CT) is an equipment to cool the water using the ambient air. In other words, CT is a final heat rejecting part in a water-cooled heat transfer system, which rejects the heat energy absorbed by the cooling system to the atmosphere.
Thus Cooling and maintaining the circulated water few degrees lower than ambient temperature is the primaiy function, of any cooling tower. This in turn reduces the work done/ Power input in a water cooled refrigeration and air - conditioning system as compared to an air cooled system.
Cooling towers are selected and installed to handle peak load at worst ambient conditions and hence capacity of the cooling tower is always higher than the required level This results in loss of energy for circulating the fixed (excess) quantity air through the CT, in turn, resulting in payment of MORE ELECTRICITY BILLS THROUGHOUT THE YEAR, except the peak load period happening occasionally in a year.
While the installed capacity cannot be altered to match the variable demand, aileast the energy consumed by the fan motor to circulate the cur can be saved to the extent of excess capacity.

DRAWBACKS OF EXISTING ENERGY SAVERS:
Presently available Cooling Tower energy savers are simple temperature controllers, which works only on the basis of manually preset water temperature. The fen stops and restarts when the basin water temperature reaches the preset point temperature, in the currently available Cooling Tower.
The set point or target point which is manually act, in «uch devices cannot actually represent the lowest possible temperature that can be achieved In s Cooling Tower. This results in operation of the Cooling Tower at the preset water temperatures throughout the year, regardless of favourable low ambient conditions, that may be prevailing, at any given time.
This preset water temperature may coincide with the lowest possible temperature in a particular season, in a particular day that too in particular hours of a day. Remaining parts of the year the Cooling Tower is not optimised to achieve lowest possible temperature which is equal to the Wet Bulb temperature of the ambient air.
However, when the ambient temperatures itself drops below these set points, these energy savers actually increase the power consumption of the overall system by not allowing the CT fan to cool the water below the set point. Where more energy is spent on main equipment for rejecting the heat at higher water temperatures than the savings achieved by stopping the fen through these controllers, the very purpose of Cooling Tower is defeated.
Therefore, the plant engineers are compelled to discard or bye-pass these controllers at this point, otherwise the overall energy wastage goes
unnoticed.
OBJECTS OF THE INVENTION:
Accordingly it is the primary object of the invention to invent a new device which can save energy consumed by the Cooling Tower fens WITHOUT COMPROMISING THE VERY PURPOSE OP COOLING TOWER AND EXPLOITING THE FAVOURABLE AMBIENT CONDITIONS.

It is another object of the invention to aid improvement of the overall efficiency of the Cooling system.
Further objects of the invention will be clear from the following description. Now the invention will be described in detail in the following description. The nature of invention is described in detail in this complete specification.
SUMMARY OF INVENTION:-
The novel invention, consisting of A PAIR OF SENSORS, invented by me alter years of experience in the industry, is the result of extensive research, investigation, constant study, meticulous labour and unstinted effort
It is a unique product and there is no other product, which carries out the functions of temperature sensing, indicating and controlling as pro-activefy, as the invention, with a view to improve efficiency and conserve power. Vast and extensive trials establish the use of my invention, in no uncertain terms.
LATENT ENERGY SAVING COOLING TOWER: The present invention is an electronic device which consists of a set of electronic and electrical circuits to compare the difference between two input values from two temperature sensors connected to it and gives ON/OFF control output to a motor starter OK gives variable current/ voltage output to a Variable Frequency Drive (VFD) which can vary the rotating speed of the Cooling Tower fan to match the system demand. Hence this may be teimed as "DUAL SENSOR DIFFERENTIAL TEMPERATURE CONTROLLER", The sensors are of Resistance Temperature Detector (RTD) type utilising PT 100 temperature sensors housed in a Stainless Steel (S.S) tube and sealed.
The UNIQUE method of Taking two RTD inputs, directly (without any transmitters) comparing them, to give an output* IS NOT USED BEFORE, Though more than one temperature inputs from various RTD's, in various forms are used in electronic controllers, accepting two RTD inputs directly, for comparing and to give an output is a new, novel economical method.

The essence of the invention is "Utilising this dual sensor type differential temperature controller for Cooling Tower Energy saving. The invented device uses one sensor to check the water temperature of the CT outlet or in Cooling Tower basin as in prevailing controllers and the SECOND Sensor, senses the Ambient Wet Bulb Temperature, This second sensor is covered with cotton wick to sense the ambient air Wet Bulb Temperature as depicted in the drawing and described in the description of the drawing contained in this complete specification.
The invented device has widespread applicability in many industries, wherein apart from saving water and precious power to the nation, the invention will also ensure monetary savings to the industries besides maintaining efficiency of their systems and processes.
The difference between Water temperature and ambient air Wet Bulb Temperature is called the "APPROACH" of a Cooling Tower at any given point of time and load. This 'APPROACH* varies according to efficiency of a Cooling Tower. The efficiency is affected by water flow, inlet water temperature, airflow, wet surface area etc. But this approach remains constant throughout the year when the efficiency is constant Therefore, "APPROACH* is a measure of efficiency of CT, which can be ascertained from this device, as a ready reference, at any time of the operation and this is a useful tool for cross checking the improvement after any major maintenance activity in a Cooling Tower (CT).



The novel invention applies uniformly to many industries having various specified applications such as Air conditioning plant, Air Compressor, chilled water plant, processing industries and Generator sets with equal efficiency.
The invention provides a Device of COOLING TOWER ENERGY SAVER for saving energy consumed hy the fen in a cooling tower operation fitted to a cooling tower having a water in-let, a water out-let and an overhead fen characterized in that the energy saver comprises: (i) Two signal reception means to receive signals from Resistance Temperature Devices (temperature sensors), one being placed at the water out-let which senses the temperature of water therein and the other being placed near the cooling tower which senses the ambient air temperature, which are all connected through sensor cables (ii) A comparing means to compare the signals from both Resistance Temperature Devices (RTDs) and to decide upon; and (iii) A Variable Frequency Drive/ Fan Starter to send conditional electric supply to the Pan Motor in such a way that the Fan is switched on/off/speed of the fen varied by which the power consumption is minimized. The invention further provides a method of Saving Energy spent by the fan(s) in a cooling tower characterized in the stoppage of rotation of fan(s) when the water reaches ambient temperature, restarting the fen(s) when the temperature of water increases above the ambient temperature and regulating the speed of fan(s), as required by means of feedback as received by the Energy Saving Controller from the sensors sensing ambient temperature and water temperature concurrently and as conveyed to the fen motor through the fen starter/Variable frequency drive.
The studies in various applications reveal generally the following pattern:



The invention is illustrated with reference to the enclosed drawings as under:
As per drawing sheet No. 1, Warm water from the process 'C' enters the Cooling Tower {CI) at the top of which a rotating fan 'D' is fixed. In the normal circumstances, the fan constantly keeps on rotating hi order to cool the warm water entering the Cooling Tower, which results in indiscriminate loss of power. Above the fen 'D' is located the air outlet *E' while the ambient air inlet remains (marked F). However, Energy saving controller 'G' the subject of my invention fitted alongside, has 2 sensor cables 'H' to the end of which are attached Wet Bulb Sensor (marked A) and sensor *B' for reading water temperature leaving the cooling tower (marked J). The relay output of the Energy Saving Controller is connected to a fan starter/Variable Frequency Drive (Marked I), which, in turn, is connected to the fen motor operating over the cooling tower. The wet bulb temperature of ambient air and temperature of cooling tower at water basin are constantly read, through the sensors feed back*
Though in the drawing, the location of wet bulb sensors1 is indicated at a position below the Cooling Tower (CT) basin, actually this Wet bulb Sensor can also be located anywhere near the cooling tower so as to sense the condition of inlet air. Hie cotton wick will be supplied with water from a separate container to compensate the evaporation loss.
The energy saving controller 'G' through the medium of fen starter/variable Frequency Drive (VFD) T ensures the stoppage/restarting/speed regulation of the fan, as may be necessary and as described earlier in the complete specification. the drawing sheet Nos.2 and 3 include description of the Wet Bulb sensor construction and the temperature sensor meant for measuring the water temperature. As described in drawing sheet No, 2, it is important to ensure that the other end of cotton wick 'K', emanating from the sensor, is kept dipped in constant source of water (CT Basin) to facilitate supply by capillary action. Drawing sheet No.3, shows a temperature sensor 'B' measuring the water flowing through the pump/process 'J'



I claim:
1. A Device of COOLING TOWER ENERGY SAVER for saving energy
consumed by the fan in a cooling tower operation fitted to a cooling
tower having a water in-let. a water out-let and an overhead fen
characterized in that the energy saver comprises:
(i) Two signal reception means to receive signals from
Resistance Temperature Devices (temperature sensors), one being placed at the water out-let which senses the temperature of water therein and the other being placed near the cooling tower which senses the ambient air temperature, which are all connected through sensor cables.
(ii) A comparing means to compare the signals from both
Resistance Temperature Devices (RTDs) and to decide upon; and
(iii) A Variable Frequency Drive/Fan Starter to send
conditional electric supply to the Fan Motor in such a way that the Pan is switched on/off/speed of the fen varied by which the power consumption is minimized,
2. A Device as claimed in Claim (1) in which starter has a provision of
15 minutes on delay time.

3. A Device as claimed in Claim (1) wherein the Sensor (Wet Bulb Sensor) detecting the ambient air temperature is covered with Cotton Wick which is supplied with water from a separate container to offset evaporation loss.
4. A Device as claimed in Claim (1) wherein the Fan Starter stops the fan(s) when the temperature of water reaches the ambient temperature and re-starts the Fan(s) when the temperature of water goes up above the ambient temperature.
5. A Device as claimed in Claim (1) wherein the Variable Frequency Drive facilitates regulation of speed of the Fan(s) operating over the Cooling Tower, as required for the temperature control of water.
6. A Device as claimed in Claim (1) wherein the Sensor Cable is a compensated 3-core cable having any specific length.
7. A Device as claimed in Claim (1) wherein the Relay Contact Rating is 5 AMPS.
8. A Device as claimed in Claim (1) further comprising Hour Counter and Timer for evaluating efficiency*
9. A method of Saving Energy spent by the fen(s) in a cooling tower characterized in the stoppage of rotation of fan(s) when the water reaches ambient temperature, restarting the fan(s) when the

temperature of water increases above the ambient temperature and regulating the speed of fan(s), as required by means of feedback as received by the Energy Saving Controller from the sensors sensing ambient temperature and water temperature concurrently and as conveyed to the fan motor through the fan starter/Variable frequency drive.
10. A Device of Cooling Tower Energy Saver substantially as described
hereinbefore with reference to the accompanying drawings.
11. A method of saving energy in a cooling tower substantially as
described hereinbefore with reference to the accompanying
drawings.


Documents:


Patent Number 207523
Indian Patent Application Number 47/MAS/2003
PG Journal Number 27/2007
Publication Date 06-Jul-2007
Grant Date 14-Jun-2007
Date of Filing 16-Jan-2003
Name of Patentee SUBRAMANIAM BASKER
Applicant Address FLAT C,VETRI APARTMENTS, #10,SABAPATHY STREET, SEMBIUM,PERAMBUR, CHENNAI-600 011
Inventors:
# Inventor's Name Inventor's Address
1 SUBRAMANIAM BASKER FLAT C,VETRI APARTMENTS, #10,SABAPATHY STREET, SEMBIUM,PERAMBUR, CHENNAI-600 011
PCT International Classification Number G05D23/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA