Study into the Influence of Internal Heat Sources on the Operating Characteristics of a Thermoelectric Generator

Abstract

The influence of internal heat sources on temperature distribution during the operation of thermoelectric generators (TEG) is investigated. Taking into account various factors affecting the temperature regime, including internal heat sources, a multilevel model of a two-stream TEG has been developed, which allows one to calculate the temperature distribution and the integral characteristics of the generator. The calculations were carried out using the PHOENICS program package; as a result, the dependences of the electrical characteristics and the temperature drop on the junctions on the load resistance, speed, and coolant temperature were obtained. A comparison is made with the corresponding indicators in the absence of internal heat sources. It is concluded that the influence of internal heat sources on the temperature drop and electric power increases with decreasing load resistance. Thus, in the maximum power mode, which corresponds to the ratio of the load resistance to the internal resistance of the module m = 1.15, the temperature drop decreases by 3.5–4.0%, while that at m = 0.01 is by 7.5–8.5%. TEG power in maximum power mode decreases by 7.5–8.0%. Studies have shown that the influence of internal heat sources on the characteristics of the TEG is more substantial when the flow rate in the heat exchangers is lower. The greatest decrease in the values of indicators due to the influence of internal sources was observed at v = 0.2 m/s and amounted in maximum power mode to 5.5–6.0% for the temperature difference and 12–13% for power. The results obtained indicate that the influence of internal sources on the characteristics of TEGs is significant enough, which implies that the most accurate estimates of the thermal and electrical performance of TEGs can be made only by taking into account the effect of internal heat sources on the temperature distribution in TEGs.