Performance Analysis of Transcritical CO2 Quasi-Secondary Compression Cycle with Ejector Based on Pinch Point

To investigate the performance of transcritical CO2 quasi-secondary compression cycle with ejector (TCIEJ) for heat pump water heaters, thermodynamic model TCIEJ is established based on pinch point, and TCEX, TCEJ, TCI are selected as comparisons. The effects changing high pressure ambient temperature heating COP compressor exhaust analyzed, influence cooling inlet outlet vapor injection further analyzed. results show that there optimal pressures make four cycles reach maximum value, which has best performance. At an −15 °C, increased by about 20.5%, 14.9%, 7.9% compared TCI. With increase in temperature, continues to increase, corresponding gradually increases. Selecting geometric mean evaporation TCIEJ, error small actual pressure. correlation formula fitted according simulation results.