Experimental investigation of heat pipe thermoelectric generator

Abstract

Thermoelectric generators can generate electricity directly from low-temperature energy sources, such as solar and geothermal energy. Because of the low heat flux of the heat source, heat pipes are used to increase the hot end temperature of the thermoelectric module, and thus improve its conversion efficiency. We developed a heat pipe thermoelectric generator and quantitatively studied the effects of the heating power of the heat pipe evaporator and the number of modules used in the condenser, on the thermoelectric performance, heat transfer characteristics, and temperature uniformity of the generator. As the heating power increased, the heat pipe thermal resistance decreased, and the thermoelectric conversion efficiency increased. As the number of thermoelectric modules increased, the proportion of heat pipe thermal resistance increased and became dominant, which caused the hot end temperature of the modules to decrease. The system attains maximum efficiency when there is only a single module at the condenser. The temperature of the evaporator can be effectively increased to improve the output power. When the temperature of the evaporator remained constant, increasing the number of modules reduced the temperature of the hot end slightly, however, the output power was greatly improved, and the maximum output power reached 10.85 W with four modules used in the experiment. The non-uniformity of the module output performance was obvious at a low heat flux, and the module output power was high near the evaporator. These results contribute to understanding the working characteristics of heat pipe thermoelectric generators and provide some guiding significance for the optimization of generator operations.