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An Experimental Study on the Performance of Outdoor Heat Exchanger for Heat Pump Using $CO_{2}$  

Chang Young Soo (Thermal/flowtrol Research Center, Korea institute of Science of Technology)
Lee Min Kyu (Thermal/flowtrol Research Center, Korea institute of Science of Technology)
Ahn Young San (Thermal/flowtrol Research Center, Korea institute of Science of Technology)
Kim Young Il (Thermal/flowtrol Research Center, Korea institute of Science of Technology)
Publication Information
Korean Journal of Air-Conditioning and Refrigeration Engineering / v.17, no.2, 2005 , pp. 101-109 More about this Journal
Abstract
The purpose of this study is to investigate the performance of outdoor heat exchanger for heat pump using carbon dioxide. Two types of fin and tube heat exchangers (2 rows for type A and 3 rows for B) are tested. Both heat exchangers have counter-cross flow and 1-circuit arrangement. Test results such as heat transfer rate, pressure drop characteristics and temperature distribution in the heat exchanger are shown with respect to mass flow rate of refrigerant and frontal air velocity For cooling mode, the minimum temperature difference between air and refrigerant of type B is smaller than that of type A by $1^{circ}C$, but the pressure loss of air side is much higher for type B by $29\%$. It is found that a large temperature gradient of carbon dioxide during gas cooling Process Promotes thermal conduction through tube wall and fins which results in degradation of heat transfer performance. For heating mode operation, type B heat exchanger shows higher heat transfer performance compared to type A. However, because pressure loss of refrigerant side of type B is much greater than that of type A, the refrigerant outlet pressure of type B becomes lower than that of type A.
Keywords
Heat pump; Carbon dioxide; Outdoor heat exchanger; Gas coolingEvaporation;
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