Experimental study on performances of flat-plate pulsating heat pipes coupled with thermoelectric generators for power generation

Waste heat recovery for thermoelectric power generation is an important way to achieve carbon peaking and carbon neutrality goals. In this paper, the performances of flat-plate pulsating heat pipe (PHP) coupled with thermoelectric generators (TEGs) under constant heating temperature and constant heating power conditions were comparatively studied. It investigated the effects of type, number and layer number, connection mode, and installation mode of TEGs on the performances of the coupling system. Results indicate that there are different optimal types of TEGs in the coupling system under different conditions. The effects of connection mode, installation mode and cooling water flow rate on the maximum output power of the coupling system appear to be negligible. Under constant heating power conditions, the increase in the number of TEGs reduces the maximum output power and conversion efficiency. Three-layer TEGs can optimize the performances of the coupling system, and the maximum output power and open-circuit voltage can reach 4.115 W and 22.3 V at the heating power of 160 W. However, under constant heating temperature conditions, the effects of number and layer number on output power are completely opposite to those at constant heating power conditions. The maximum conversion efficiency of the coupling system is 4.40% at the heating temperature of 100 ℃. For thermal performances of the coupling system, the effective thermal conductivity can be up to 873 W/(m·K) and the thermal resistance is only about 0.1 ℃/W. The coupling system has broad application prospects in the fields of driving LED lamps and producing hydrogen by water electrolysis.