An alkali metal thermoelectric converter/thermally regenerative electrochemical cycles/absorption refrigerator coupling system for power and cooling

Abstract

The performance of an alkali metal thermoelectric converter (AMTEC) is restricted by the generation of surplus waste heat, so utilizing waste heat is a potential way to enhance the energy exchange efficiency of AMTEC. In this work, a novel coupling system comprised of an AMTEC, thermally regenerative electrochemical cycles (TRECs) and an absorption refrigerator (AR) is proposed, in which the waste heat is spilt into two parts to drive TRECs and AR to content with the actual demand for power and cooling. Taking into account the external heat leakage as well as the principal irreversible losses in the system, the equivalent power output and efficiency of the system are expressed mathematically. Furthermore, the generic performance features are demonstrated as well as optimum operation regions of the coupling system are obtained. After optimizing the proportional coefficient of heat flow distribution and the current density of the AMTEC, the maximum power output (MPO) and maximum efficiency (ME) could reach 29.49 W and 0.35, respectively. Meanwhile, the MPO and ME of the coupling system are 45 % and 28 % larger than the separate AMTEC system, and are also significantly higher than AMTEC/TRECs and AMTEC/AR. Finally, the impacts of the critical parameters on the systemic performance are evaluated, including the temperature-independent exchange current coefficient, the internal resistance, the regenerative efficiency and the heat-transfer coefficients. The present study may provide a new route for AMTEC to improve the conversion efficiency.