A high-efficient thermoelectric generator with a built-in field

Abstract

An analytical model is developed in this work to evaluate the maximum efficiency of a new thermocouple designed with a built-in electric field. The built-in field in the thermocouple, which is characterized by the electrostatic voltage between the hot-and the cold-sides, is created by the metallurgical junctions formed between the n-and the p-type legs and between these legs and their semiconductor emitters embedded on their exterior surfaces. For the upper bound electrostatic voltage which equals the value of the Seebeck voltage, the analytical model showed that the maximum efficiency can be enhanced up to 2-4 times that of the same thermocouple without the metallurgical junctions. The model further showed that when the mean ZT of the legs was greater than 1.5, the efficiency could be better than a heat engine, which has never been reported. The output power of the thermocouple was also studied and showed a similar trend as that of the maximum efficiency. Numerical simulations conducted on the thermocouple using various combinations of the legs’ and the emitters’ doping densities supported these model predictions. This work indicates that a thermocouple can achieve an efficiency that can exceed that of its legs’ materials or even the Carnot efficiency for a heat engine through design innovation.