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Experimental study of R134a/R410A cascade cycle for variable refrigerant flow heat pump systems
김정훈,이재완,최환종,이상훈,오새기,박원규 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.12
Cascade cycle is widely applied to heat pumps operating at low ambient temperature to overcome problems such as low heating capacityand Coefficient of performance (COP) deterioration A number of researches have been conducted on cascade cycle heat pumps, butmost of those studies were focused on system optimization to determine optimal intermediate temperature in air-to-water heat pumps. However, experimental optimization in regard to air and water heating simultaneously using a cascade cycle has been an understudiedarea. Therefore, we focused on experimental analysis for a cascade system with Variable refrigerant flow (VRF) heat pumps. Experimentswere conducted under a variety of operating conditions, such as ambient and water inlet temperature. COP increased up to 16%when water inlet temperature decreased. COP of VRF heat pumps with cascade cycle is three-times higher compared with conventionalboilers as well as 17% higher compared to single heat pumps.