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Experimental Study on the Performance of Water Source Trans-Critical CO2 Heat Pump Water Heater
- Source :
- Energies, Vol 10, Iss 6, p 810 (2017)
- Publication Year :
- 2017
- Publisher :
- MDPI AG, 2017.
-
Abstract
- 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.
- Subjects :
- trans-critical CO2 cycle
heat pump
optimal discharge pressure
COP
Technology
Subjects
Details
- Language :
- English
- ISSN :
- 19961073
- Volume :
- 10
- Issue :
- 6
- Database :
- Directory of Open Access Journals
- Journal :
- Energies
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.19fd1ce3a82481aabc731914e252191
- Document Type :
- article
- Full Text :
- https://doi.org/10.3390/en10060810