Performance analysis of transcritical CO2 air source heat pump system with different jet enthalpies

The models of traditional circulation system, ejector heat pump circulation system, flash evaporator circulation system, economizer circulation system and expander circulation system are established, and the typical heating conditions are analyzed. The effects of five systems on the COP and exhaust pressure of the system at the return water temperature of 28 °C, 40 °C and 50 °C in the variable ambient temperature of-20 ~ 10 °C were studied. The results show that the COP of the system decreases with the increase of the return water temperature. When the return temperature of the water is below 40 °C, the expander cycle heat pump system's expander efficiency is higher than the ejector cycle efficiency. When the ambient temperature is 10 °C, the expander heat pump cycle is 15.6 % higher than the ejector cycle heat pump. When the recirculating fluid temperature rises over 40 °C, the ejector cycle heat pump system's efficiency surpasses that of the expander. When the ambient temperature is 0 °C, the ejector cycle heat pump is 9.6 % higher than the expander cycle heat pump.