Abstract
Thermoelectric power generators are used to convert heat into electricity. Like any other heat engine, the performance of a thermoelectric generator increases as the temperature difference on the sides increases. It is generally assumed that as more heat is forced through the thermoelectric legs, their performance increases. Therefore, insulations are typically used to minimize the heat losses and to confine the heat transport through the thermoelectric legs. In this paper we show that to some extend it is beneficial to purposely open heat loss channels in order to establish a larger temperature gradient and therefore to increase the overall efficiency and achieve larger electric power output. We define a modified Biot number (Bi) as an indicator of requirements for sidewall insulation. We show cooling from sidewalls increases the efficiency for Bi values less than one, and decreases the efficiency for Bi values larger than one.
Highlights
Thermoelectric power generators are used to convert heat into electricity
In this paper we show that to some extend it is beneficial to purposely open heat loss channels in order to establish a larger temperature gradient and to increase the overall efficiency and achieve larger electric power output
We show cooling from sidewalls increases the efficiency for Biot number (Bi) values less than one, and decreases the efficiency for Bi values larger than one
Summary
Thermoelectric power generators are used to convert heat into electricity. Like any other heat engine, the performance of a thermoelectric generator increases as the temperature difference on the sides increases. Typical commercial thermoelectric devices are made out of Bi2Te3/Sb2Te3 for room temperature applications and PbTe for high temperature applications and they have a ZT of around 1 These modules are made out of many p-n legs, which are placed thermally in parallel and electrically in series. There is a factor-of-two difference between ideal and practical efficiency, which could be attributed to thermal/electrical contact resistances, and non-ideal heat managements (operational conditions). Both issues have been largely studied in the literature in the past. We would like to address the heat management issue It has been shown by several authors, that heat loss through sidewalls of thermoelectric legs, result in lowering of the thermoelectric efficiency[10,11,12]. The purpose of this article is to point to practical issues resulting in cases, wherein opening of heat loss channels, improves the efficiency!
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