Thermodynamic analyses and optimization of a recompression N2O Brayton power cycle

Abstract

Thermodynamic analyses and simultaneous optimizations of cycle pressure ratio and flow split fraction to get maximum efficiency of N2O recompression Brayton cycle have been performed to study the effects of various operating conditions and component performances. The energetic as well as exergetic performance comparison with its counterpart recompression CO2 cycle is presented as well. Optimization shows that the optimum minimum cycle pressure is close to pseudo-critical pressure for supercritical cycle, whereas saturation pressure corresponding to minimum cycle temperature for condensation cycle. Results show that the maximum thermal efficiency increases with decrease in minimum cycle temperature and increase in both maximum cycle pressure and temperature. Influence of turbine performance on cycle efficiency is more compared to that of compressors, HTR (high temperature recuperator) and LTR (low temperature recuperator). Comparison shows that N2O gives better thermal efficiency (maximum deviation of 1.2%) as well as second law efficiency compared to CO2 for studied operating conditions. Component wise irreversibility distribution shows the similar trends for both working fluids. Present study reveals that N2O is a potential option for the recompression power cycle.