6. Thermodynamic Analysis of N₂O Transcritical Cycle Using Dedicated Mechanical Subcooling

The thermodynamic analysis to improve the energetic performance of N₂O transcritical cycle using dedicated mechanical subcooling is done for three different evaporator temperatures 5, −5 and −30 °C. The analysis is done for the environment temperature ranging from 30 to 40 °C. Propane is used as a refrigerant in mechanical subcooling cycle. It has been found that if combined cycle is used, the maximum increments in COP and specific cooling capacity (SCC) are 22% and 30%, respectively. It has also been found that using mechanical subcooling cycle, the reduction in optimum heat rejection pressure is higher at lower evaporator temperature, i.e. −30 °C and power consumption ratio is higher at higher evaporator temperature, i.e. 5 °C. Further, COP increment using different refrigerants in mechanical subcooling cycle has been presented, where no significant differences have been found. The increment indicates that this cycle is more efficient if the environment temperature is more than 30 °C.