Evaluation of the energy system variable operating conditions under the lunar environment

Abstract

The periodic fluctuations of the heat and cold sources on the moon cause changes in the operating efficiency of the equipment within the energy system. Thus, the thermodynamic performance of the energy system cannot be evaluated through research under the design point conditions. In order to accurately evaluate the power generation characteristics, this paper establishes off-design operating conditions model of the closed Brayton cycle (CBC)-organic Rankine cycle (ORC) system considered lunar surface temperature and radiation intensity. It is found that 10,000 rpm is suitable for the lunar daytime, and the average power generation can reach 63.99 kW under the constant speed mode of the compressor and turbine. Under the constant power output mode, the average power generation is 56.43 kW. The constant speed output mode is more suitable for the lunar daytime. During the lunar night, due to the significant decrease in the lunar surface temperature, the power generation of ORC is enhanced. Under the constant speed output mode, when CBC is stopped on the 19th earth day, the average power generation can reach a maximum of 178.81 kW. Under the constant power output mode, the constant output power range of CBC-ORC is 42.25 kW to 184.56 kW. Considering the continuous operation of life support equipment during the lunar night, it is more appropriate to select the constant power output mode. This study takes into account the operating characteristics of the lunar energy system throughout the lunar day, fully considers the changes in the heat and cold sources at the lunar base, and provides certain guidance for the practical operation of the energy system.