In order to improve the performance of CO2 air source heat pump water heater, an experimental device was built, and the effects of cooling water flow, high pressure and compressor frequency were tested. Furthermore, the simulation model of trans-critical CO2 quasi-two-stage compression heat pump with ejector （TCIEJ) was established, and the system performance was simulated. The results show that when the flow rate of cooling water increases from 70 kg/h to 122.5 kg/h, COP increases by 30%, while the outlet temperature of cooling water decreases by 15.4%. With the increase of high pressure, the COP has a maximum value, the outlet temperature of gas cooler and cooling water both increase. When the compressor frequency increases from 110 Hz to 180 Hz, the exhaust pressure increases by 22.3%, but COP decreases by 44.6%. When the high pressure of TCIEJ system increases from 8.0 MPa to 10.4 MPa, the outlet temperature of cooling water increases by 17.66 ℃, even when the ambient temperature is 0 ℃ and the high pressure reaches 10.4 MPa, the exhaust temperature of the compressor is only 85.77 ℃, this system is conducive to improving the compression process. When the flow rate of cooling water increases from 60 L/h to 100 L/h, the outlet temperature of cooling water decreases by 6.8 ℃.
Key words
CO2 /
air source heat pump /
quasi-two-stage /
ejector /
system performance
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