Experimental Study on the Performance of Water Source Trans-Critical CO2 Heat Pump Water Heater

Energies

Changhai Liu¹  Liang Chen²  Yu Hou²  Xiufang Liu²  Ze Zhang² 

[1] School of Civil Engineering, Zhengzhou University, Zhengzhou 450001, China;State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China;

关键词: trans-critical CO2 cycle;    heat pump;    optimal discharge pressure;    COP;   

DOI  :  10.3390/en10060810

来源: DOAJ

【 摘 要 】

The effect of the discharge pressure on the performance of the trans-critical CO2 heat pump with a low gas-cooler outlet temperature is experimentally investigated on a test rig of water source heat-pump water heater. The optimal discharge pressure of the trans-critical CO2 heat pump is investigated under different external operation conditions. When the tap-water temperature is low, the characteristic of the S-shape isotherm at the supercritical region has little effect on the occurrence of the optimal discharge pressure; while the mass flow rate of CO2, the suction pressure and the gas-cooler outlet temperature play a significant role in determining the emergence of the optimal discharge pressure. At the optimal discharge pressure, the COP reaches the peak; however, the corresponding heating capacity is still lower than its maximum, which is reached as the discharge pressure is slightly above the optimal discharge pressure. Reducing the tap-water flowrate or increasing the water-source temperature can increase the optimal discharge pressure. The COP is positively dependent on both the tap-water flowrate and the water-source temperature. In addition, the tap-water flowrate has a negligible influence on the maximum heating capacity while increasing the water-source temperature can greatly enhance the heating capacity.

【 授权许可】

Unknown