Field test investigation of the characteristics for the air source heat pump under two typical mal-defrost phenomena

W. Wang, J. Xiao, Q.C. Guo, W.P. Lu and Y.C. Feng

Applied Energy, 2011, vol. 88, issue 12, 4470-4480

Abstract: A study is presented on the characteristics of the air source heat pump (ASHP) under two kinds of typical mal-defrost phenomena. The definition of the “Mal-defrost phenomena” is put forward, and the possible origins of their occurrence are analyzed. It is concluded that the current defrost strategies may cause mal-defrost phenomena due to the lack of the direct control information, frost thickness. Transient characteristics of the tested ASHP under these mal-defrost phenomena are investigated by field tests. Instant frosting images are captured to record the dynamic frosting process. In the first phenomenon of mal-defrost, the defrost control is carried out over an hour after a “critical” level of frosting has been reached. It reduces the COP and heating capacity by about 17.4% and 29%, respectively. In the second phenomenon of mal-defrost, three defrost operations occur while almost no frost is observed on the heat exchanger during 6h testing period. It causes 4.2% decrease for the heating efficiency.

Keywords: Air source heat pump; Mal-defrost; Heating efficiency; Heating capacity (search for similar items in EconPapers)
Date: 2011
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (19)

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DOI: 10.1016/j.apenergy.2011.05.047

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