Effects of surface heat transfer on the performance of a thermoelectric generator

Abstract

Analytical solutions are given for the steady-state temperature distribution, power output, and efficiency of a thermoelement which is used in a thermoelectric power generator. The longitudinal surface of the thermoelement is divided into three regions. The first region is exposed to convection with the environment at the cold junction; the second region is thermally insulated; the third region is exposed to convection with the environment at the hot junction. The relative sizes of the three regions are variable. The solutions are useful for predicting the performance of thermoelectric power generators and for showing the improvements in performance that can be gained through the use of surface heat transfer. It is shown that substantial increases in the power output can be gained if the thermoelements are exposed to surface heat transfer. It is possible to use surface heat transfer to reduce greatly the amount of fin surface needed at the hot and cold junctions. A numerical example is presented in which no fins are used at the hot and cold junctions; it is shown in this example, that, by using surface heat transfer, 97 per cent of the maximum theoretical output can be achieved.