Performance Analysis of CO2 Heat Pump Water Heater with an Ejector

CO₂ trans-critical cycle has a large loss of expansion work, based on this, use an ejector in the system to recover expansion work. This paper focused on the CO₂ heat pump water heater with an ejector, established a model for it on the basis of equal pressure mixture theory, and analyzed operating parameters and the ejector´s influence on system performance. It is found that: Coefficient Of Performance (COP) of the CO₂ trans-critical cycle system with an ejector is increased 16% than non-ejector system and the CO₂ trans-critical system with an ejector has big application value; entropy of ejector accounts 22% of the total entropy change, and appropriate design of ejector is very important to optimize overall system performance.