Numerical study of temperature distribution and performance optimization of radioisotope thermophotovoltaic system

The optimized design of radioisotope thermophotovoltaics system can enhance the utilization of Pu-238 in deep space exploration. A 3-dimensional coupled thermal-optical-electrical numerical model based on step 2 general purpose heat source is developed to analyze the effect of temperature and radiant flux on system efficiency. Calculations show that when the number of heat sources is increased to 8, the module temperature saturates from 943.9 °C to 986.96 °C. Under a certain heat dissipation capacity, for the 250 W system, the optimal distance is 0.5 cm, the system efficiency is 17.9%, and the specific power is 9.49 W/kg. For the 1000 W system, the optimal distance is 1.5 cm, the system efficiency is 22.67%, and the specific power is 14.75 W/kg. For the 2000 W system, the optimal distance is 2.5 cm, the system efficiency is 23.96%, and the specific power is 13.85 W/kg. By analyzing the energy distribution of different power systems, the high power system has high thermal utilization, high emitter temperature and high system efficiency. Enhanced heat dissipation results in system efficiency of up to 25.06%. This provides a novel and promising energy supply technology solution for addressing the power supply challenge in deep space exploration. • Development of a multi-module step 2 general purpose heat source radioisotope thermophotovoltaic model. • A new approach to study the temperature effect on system optimization from the system structure is proposed. • Increasing the number of heat sources and optimizing the spacing are effective ways to improve system performance. • The system's internal emitter temperature is projected to reach as high as 982.62 °C.