Experimental study on the thermoelectric performance of a thermoelectric generator integrated with a gravity heat pipe

A gravity heat pipe (GHP) - integrated thermoelectric generator (TEG) utilizes the superior thermal conductivity of the GHP to facilitate efficient thermal exchange between the heat source/sink and the thermoelectric modules, exhibiting greater thermoelectric conversion efficiency and considerable potential for practical applications. In this study, a GHP-TEG is developed, and the effects of heating heat flux and GHP inclination angle on the GHP-TEG performance are quantitatively investigated. The experimental results show that as the heating heat flux is increased from 4500 W/m² to 10,500 W/m², the GHP thermal resistance is reduced by 31.30%, accompanied by substantial improvements in both output power and thermoelectric conversion efficiency. At a heating heat flux of 10,500 W/m², the system attains a maximum output power of 5.34 W and a thermoelectric efficiency of 2.54%. An increase in the GHP inclination angle leads to a reduction in its thermal resistance; however, owing to the relatively small contribution of the GHP thermal resistance to the overall thermal resistance, the inclination angle exerts a limited influence on thermoelectric performance. At a heating heat flux of 7500 W/m², the generator achieves its maximum output power at an inclination angle of 90°, which is 7.34% higher than that recorded at 5°. The findings of this study offer experimental support for the optimization of GHP-TEG structures and operating strategies, and provide a useful reference for enhancing the efficiency of waste heat recovery systems.