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http://dx.doi.org/10.6110/KJACR.2011.23.4.273

Experimental Study on the Performance of a CO2 Heat Pump Water Heater under Various Operating Conditions  

Sohn, Dong-Jin (Graduate School of Mechanical Engineering, Korea University)
Baek, Chang-Hyun (Graduate School of Mechanical Engineering, Korea University)
Heo, Jae-Hyeok (Department of Mechanical Engineering, Korea University)
Kang, Hoon (Department of Mechanical Engineering, Korea University)
Kim, Yong-Chan (Department of Mechanical Engineering, Korea University)
Publication Information
Korean Journal of Air-Conditioning and Refrigeration Engineering / v.23, no.4, 2011 , pp. 273-280 More about this Journal
Abstract
In this study, the steady state performance of a $CO_2$ heat pump water heater was measured with a variation of operating conditions such as refrigerant charge amount, compressor frequency, EEV opening, and water mass flow rate. Transient state performance tests were also conducted to investigate major system effects associated with the interaction between the $CO_2$ heat pump water heater and the water tank. Optimum refrigerant charge amount for the system was 1600 g. At compressor frequencies of 50 Hz and 60 Hz, water mass flow rates of 95 kg/h and 105 kg/h, and EEV opening of 8% and 16%, the water heating temperatures were $65^{\circ}C$ and $68^{\circ}C$ and COPs were 3.0 and 2.8, respectively. In the transient condition, the instantaneous COP decreased with an increase in the inlet water temperature.
Keywords
$CO_2$ heat pump water heater; Water heating temperature; Coefficient of Performance(COP);
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