Heat exchanger for thermoelectric applications
A thermoelectric system (10) for pumping heat having at least one foam heat exchanger (45) is provided that enhances heat transfer away from the system (10) to increase overall system efficiency and performance of the system.
1. Field of the Invention
This invention relates generally to foam heat exchangers, and more particularly, to an apparatus and method for enhancing heat transfer in thermoelectric systems using foam heat exchangers.
2. Description of Related Art
The use of heat exchangers to dissipate heat in power electronics applications is well known. Heat exchangers or heat sinks are frequently metal radiators designed to remove heat from power electronics components, particularly, power transistor modules, by thermal conduction, convection or radiation. Without heat exchangers power electronics component would suffer from reduced performance and reliability.
Heat exchangers are often structured to have a maximum number of fins per unit volume radiating in a direction perpendicular to a heated surface. In particularly demanding applications, heat exchangers dissipate heat using forced convection to a cooling fluid over the heat exchangers to increase the heat dissipation of the exchanger. An even more efficient apparatus for dissipating heat is the use of foams, and in particular metal forms, which have a more effective surface area for heat transfer. Metal foams have recently been used to dissipate heat in power electronic applications; however, they have not been used in thermoelectric systems.
Accordingly, there exists a need for foam heat exchangers to be used with thermoelectric elements to build systems for a variety of heating and cooling systems that reduce energy consumption and increase heat pumping capacity in such systems.
SUMMARY OF THE INVENTIONIt is an object of the present invention to provide thermoelectric heating and cooling systems that use foam heat exchangers.
It is also an object of the present invention to provide thermoelectric heating and cooling systems that use metal foam heat exchangers.
It is another object of the present invention to provide thermoelectric heating and cooling systems that use foam heat exchangers to dissipate heat.
It is a yet another object of the present invention to provide thermoelectric heating and cooling systems having thermoelectric elements that use foam heat exchangers to reduce the energy consumption of the thermoelectric elements.
It is still yet another object of the present invention to provide thermoelectric heating and cooling systems having thermoelectric elements that use foam heat exchangers to increase the heat pumping capacity of the thermoelectric elements.
It is a further object of the present invention to provide a method for enhancing heat transfer of thermoelectric elements using foam heat exchangers.
A system for enhancing the efficiency of a thermoelectric heat pumping system including an array of thermoelectric elements having a temperature at a first surface of the array and a temperature at a second surface of the array opposite the first surface and at least one foam heat exchanger located adjacent one of the first surface and the second surface is provided. The fluid flowing through the at least one foam heat exchanger reduces a difference between the temperature at a first surface of the array and the temperature at a second surface of the array thereby enhancing the efficiency of the system.
A method of enhancing the efficiency of a thermoelectric system having a thermoelectric array having a series of thermoelectric pairs arranged electrically in series is provided. The method provides for a first foam heat exchanger adjacent a first surface of the thermoelectric array and a second foam heat exchanger adjacent a second surface of the thermoelectric array opposite first surface; for generating a temperature at a first surface of the thermal array and a temperature at a second surface of the array that is different from the temperature at the first surface of the array; whereby fluid flowing through the first foam heat exchanger and the second foam heat exchanger reduces a temperature difference between the first surface and the second surface, thereby enhancing the efficiency of the thermoelectric system.
Referring to
In
Foam heat exchangers 45 and 55 are made from highly conductive materials such as aluminum, copper or graphite. Exchangers made from such materials are not only highly conductive, but because they are formed as a foam, they have a very high porosity and surface area to further enhance their heat transfer capacity. Traditional heat exchangers used in thermoelectric applications have fins to dissipate heat. In comparison to foam heat exchanges, finned heat exchangers have a very limited surface area. Furthermore, traditional heat exchangers are relatively heavy compared to foam heat exchangers 45 and 55 of the present invention. Reducing the weight and/or volume and increasing the heat transfer capacity of heat exchangers is of great concern when both small and large heating and cooling thermoelectric systems are used.
Referring to Table 1 in
Referring to
Foam heat exchangers 95 and 100 provide substantial heat transfer capacity across surfaces 130 and 125, respectively, compared to traditional heat sinks to increase the efficiency of system 90. By having a high heat transfer coefficient foam heat exchangers 95 and 100, a lower the temperature difference between the opposing surfaces of thermoelectric elements 120, is achieved. This low temperature difference increases the performance of the overall system 90 by consuming less energy. Thus the overall system, whether it is configured as a heating or a cooling system, has a very high performance.
Referring to
In
While the instant disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope thereof. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims
1. A system for enhancing the efficiency of a thermoelectric heat pumping system comprising:
- an array of thermoelectric elements having a temperature at a first surface of said array and a temperature at a second surface of said array opposite said first surface and
- a foam heat exchanger adjacent a first surface of said array and a foam heat exchanger adjacent a second surface of said array
- wherein fluid flowing through said foam heat exchanger adjacent said first surface and fluid flowing through said foam heat exchanger adjacent a second surface of said array reduce a difference between said temperature at a first surface of said array and said temperature at a second surface of said array thereby enhancing the efficiency of said system.
2. (canceled)
3. The system of claim 1, comprising a current flowing through said array of thermoelectric elements to generate a temperature difference between a first surface of said array and a second surface of said array.
4. The system of claim 3, wherein said at least one foam heat exchanger at one of said first surface of said array and said second surface of said array transport heat away from said array thereby reducing the current flowing through said array.
5. The system of claim 1, wherein said foam heat exchanger adjacent said first surface of said array and said foam heat exchanger adjacent said second surface of said array each have a porosity to enhance heat transfer through said array.
6. The system of claim 1, wherein said at least one foam heat exchanger incorporates fins for heat dissipation.
7. The system of claim 1, wherein said at least one foam heat exchanger is made from a material selected from a group consisting of aluminum, graphite and copper.
8. (canceled)
9. A method of enhancing the efficiency of a thermoelectric system comprising:
- providing a thermoelectric array having a series of thermoelectric pairs arranged electrically in series;
- providing a first foam heat exchanger adjacent a first surface of said thermoelectric array and a second foam heat exchanger adjacent a second surface of said thermoelectric array opposite said first surface;
- generating a temperature at said first surface of said thermal array and a temperature at a second surface of said array that is different from said temperature at said first surface of said array;
- whereby fluid flowing through said first foam heat exchanger and said second foam heat exchanger reduce a temperature difference between said first surface and said second surface, thereby enhancing the efficiency of the thermoelectric system.
10. The method of claim 9, wherein said first foam heat exchanger and said second foam heat exchanger each have a porosity to enhance heat transfer capability.
11. The method of claim 9, wherein as a temperature between said first surface and said second surface is reduced, a coefficient of performance of said system is increased.
12. The method of claim 9, wherein a reduced porosity of said first foam heat exchanger and said second foam heat exchanger further enhance heat transfer to or away from said first surface and said second surface.
13. The method of claim 9, wherein enhanced heat transfer across said first surface and said second surface reduces required current flowing through said array.
14. The method of claim 9, wherein at least one of said first foam heat exchanger and said second foam heat exchanger incorporate fins.
15. (canceled)
Type: Application
Filed: Aug 25, 2005
Publication Date: Sep 2, 2010
Inventors: Abbas A Alahyari (Manchester, CT), Louis J. Spadaccini (Manchester, CT), Xiaomei Yu (Glastonbury, CT), Thomas H. Vanderspurt (Glastonbury, CT)
Application Number: 11/990,964
International Classification: F25B 21/04 (20060101); F25B 21/02 (20060101); F28F 7/00 (20060101);