Thermodynamic performance of lunar surface nuclear power system with heat sink temperature change in a rotational period

The thermodynamic performance of the lunar surface nuclear power system with Free-Piston Stirling Engines (FPSE) was analyzed based on the energy conservation of the system. The heat sink temperature was assumed to follow the sine function law. The cold side temperature of the FPSE was changing with time in a rotational period and would be increased with the increase of the heat sink temperature. The thermodynamic performance of the power system was changing with lower thermal efficiency and high amount of exhaust heat rejection, during the day time with heat sink temperature higher than 200 K. During the dark time, the power system could be kept as a steady state with higher thermal efficiency and less amount of exhaust heat rejection. The energy storage option could be required, if the electrical power output was expected to meet the grid. The highest thermal efficiency could be increased from 0.21 to 0.235, if the area of the heat rejection system was increased from 120 m2 to 180 m2, since the cold side temperature of the PFSE could be decreased. Larger area of the heat rejection system could increase the specific area but has the advantage of lightweight for the power system.