Performance analysis and optimization of an irreversible Carnot heat engine cycle for space power plant

Abstract

In this paper, an irreversible Carnot heat engine cycle model for space power plants is built by using finite time thermodynamics. A radiator panel is considered between low temperature heat sink and space environment, expressions for power output and thermal efficiency of the plant are derived. Influences of internal irreversibility effect and thermal leakage loss on the optimal power output performance are analyzed when thermal conductivity of hot- and cold-sides heat exchangers are given. For the fixed total area of three heat exchangers the double-maximum power output and double-maximum thermal efficiency are obtained further by optimizing area distributions of hot- and cold- side heat exchangers and radiator, and by optimizing temperature of low-temperature heat sink. Influences of internal irreversibility effect and thermal leakage loss on the optimal performances are investigated. The results show that when taking power output as optimization objective, if considering thermal leakage and irreversibility effect, internal irreversibility effect increases from 1.1 to 1.3, double maximum power output decreases from 216.38 kW to 139.85 kW and decreases by 35.37%, the optimal the temperature the low-temperature heat sink decreases from 556Kto 501.1Kand decreases by 9.87%, and the optimal area allocations of hot- and cold-side heat exchangers decrease from 0.213 to 0.182 and decreases by 14.55%, from 0.213 to 0.207 and decreases by 2.82%, respectively, and that of radiator increases from 0.563 to 0.611 (an increase of 8.35%). Such temperature and area distribution condition ensure the future design of plant conversion system that aligns better performances and compactness.

Keywords

• Finite time thermodynamics
• Irreversible Carnot heat engine cycle
• Space power plant
• Power output
• Thermal efficiency
• Performance optimization