Thermodynamic analysis and optimization of a novel two-stage transcritical N 2O cycle

Abstract

Thermodynamic (energy and exergy) analyses and optimization studies of two-stage transcritical N 2O and CO 2 cycles, incorporating compressor intercooling, are presented based on cycle simulation employing simultaneous optimization of intercooler pressure and gas cooler pressure. Further, performance comparisons with the basic single-stage cycles are also presented. The N 2O cycle exhibits higher cooling COP, lower optimum gas cooler pressure and discharge temperature and higher second law efficiency as compared to an equivalent CO 2 cycle. However, two-stage compression with intercooling yields lesser COP improvement for N 2O compared to CO 2. Based on the cycle simulations, correlations of optimum gas cooler pressure and inter-stage pressure in terms of gas cooler exit temperature and evaporator temperature are obtained. This is expected to be of help as a guideline in optimal design and operation of such systems.