Thermodynamic Analysis and Comparison of Four Type CBC-ORC Energy Systems with Regenerator Using Improved Lunar Regolith for Heat Storage Applied to Lunar Base

Closed Brayton cycle (CBC)-organic Rankine cycle (ORC) system is an important option for lunar base energy system. In order to deeply explore the potential of CBC-ORC applications at lunar base, the impact of different system constructions on system performance needs to be evaluated. This paper establishes four types CBC-ORC mathematical model with different position of regenerator, and evaluates the daytime and nighttime operation characteristics of the regenerators, including thermal efficiency, thermal efficiency and power generation. The results show that the CBC regenerator can significantly improve the thermal efficiency of the system during the lunar daytime, with an increase of 15 %. However, ORC regenerator has limited improvement on system performance (only 4.28 %). In addition, the CBC regenerator can reduce the heat exchange area of solar trough collector and radiator by 60.3 % and 57.94 %, respectively. The CBC regenerator can balance the exergy destruction of each equipment, especially the evaporator. Compared with the energy system without CBC regenerator, its exergy destruction is reduced by 58 %. In summary, different demands correspond to different energy systems. Type 4 should be selected when the system is affected by limited space, high energy conversion efficiency is accomplished in limited space. If it is only to achieve high power generation, Type 3 is the best choice for the lunar base.