Numerical study on the performance of the thermoelectric generator with different air-water mixtures

Abstract

Thermoelectric generators (TEGs) have been widely used to convert thermal energy into electrical energy directly. Nowadays, the most popular TEG applications, such as vehicle heat recovery and geothermal power generation, typically utilize water as the cooling working fluid. Water sources, however, may not be available or extremely limited in some cases. Therefore, in this study, we proposed a new method of mixing water and air as the working fluid to save water. It is necessary to find out the suitable ratio of water to air, under which the performance loss could be minimized. A numerical model of TEG was built utilizing COMSOL Multiphysics to investigate the effect of water mole fraction (WMF, representing water to air ratio) on the performance of TEG, where the properties of the air-water mixture (AWM) could vary with WMF. In this study, 5 cases were considered at different flow velocities, different WMFs, and different combinations of air, water, and AWMs. The effects of these parameters on the voltage and the output power of TEGs were studied and analyzed. The TEG module could generate higher voltage and power output with increasing velocity and WMF. When air fixed on one side, only 0.2 of WMF on the other side could boost over 1.5 times of voltage and 3 times of power generation than only using air. Based on the simulation results, TEGs reach the best performance when the value of WMF is equal to 0.5 on both sides.