Experimental prototype and simulation optimization of micro-radial milliwatt-power radioisotope thermoelectric generator

Abstract

To satisfy the flexible power demand of the low power dissipation devices in the independent space electric system, a micro-radial milliwatt-power radioisotope thermoelectric generator (RTG) was prepared and optimized in this research. The overall geometrical dimension of the RTG in the experiment was 65mm (diameter)×40mm (height). The RTG, which was built and tested using simulated radioisotope source, eventually obtained an open-circuit voltage of 92.72mV, an electric power of 149.0μW, and an energy conversion efficiency of 0.015% at the ambient temperature of 293.15K and heat source power from 0.1W to 1W. On the basis of the structure used in the experiment, the length and cross-sectional area of the thermoelectric leg and the number of thermoelectric modules were effectively optimized through the COMSOL Multiphysics. With the optimized length of 35mm and cross-sectional area of 1.2mm2, the RTG with four thermoelectric modules achieved a 15.8mW output power under 1W heat source power. The maximum conversion efficiency calculated using COMSOL code increased to 1.58%. According to the optimized electrical output, the micro-radial RTG is expected to be a reliable space power supply for micro components and could satisfy the low power requirements of space missions.