TY - JOUR
T1 - An experimental study on defrosting heat supplies and energy consumptions during a reverse cycle defrost operation for an air source heat pump
AU - Dong, Jiankai
AU - Deng, Shiming
AU - Jiang, Yiqiang
AU - Xia, Liang
AU - Yao, Yang
N1 - Funding Information:
The authors wish to acknowledge The Hong Kong Polytechnic University ( G-U872 ) and The National Natural Science Fund of China (Grant No. 50606007 ) to financially support the work reported in this paper.
PY - 2012/5
Y1 - 2012/5
N2 - For a space heating air source heat pump (ASHP) unit, when its outdoor coil surface temperature is below both the air dew point temperature and the freezing point of water, frost will form on its outdoor coil surface. Frosting affects its operational performance and energy efficiency. Therefore, periodic defrosting is necessary. Currently, the most widely used standard defrosting method for ASHP units is reverse cycle defrost. The energy that should have been used for space heating is used to melt frost, vaporize the melted frost off outdoor coil surface and heat ambient air during defrosting. It is therefore necessary to study the sources of heat supplies and the end-uses of the heat supplied during a reverse cycle defrost operation. In this paper, firstly, an experimental setup is described and experimental procedures are detailed. This is followed by reporting the experimental results and the evaluation of defrosting efficiency for the experimental ASHP unit. Finally, an evaluation of defrosting heat supplies and energy consumptions during a revere cycle defrost operation for the experimental ASHP unit is presented. The experimental and evaluation results indicated that the heat supply from indoor air contributed to 71.8% of the total heat supplied for defrosting and 59.4% of the supplied energy was used for melting frost. The maximum defrosting efficiency could be up to 60.1%.
AB - For a space heating air source heat pump (ASHP) unit, when its outdoor coil surface temperature is below both the air dew point temperature and the freezing point of water, frost will form on its outdoor coil surface. Frosting affects its operational performance and energy efficiency. Therefore, periodic defrosting is necessary. Currently, the most widely used standard defrosting method for ASHP units is reverse cycle defrost. The energy that should have been used for space heating is used to melt frost, vaporize the melted frost off outdoor coil surface and heat ambient air during defrosting. It is therefore necessary to study the sources of heat supplies and the end-uses of the heat supplied during a reverse cycle defrost operation. In this paper, firstly, an experimental setup is described and experimental procedures are detailed. This is followed by reporting the experimental results and the evaluation of defrosting efficiency for the experimental ASHP unit. Finally, an evaluation of defrosting heat supplies and energy consumptions during a revere cycle defrost operation for the experimental ASHP unit is presented. The experimental and evaluation results indicated that the heat supply from indoor air contributed to 71.8% of the total heat supplied for defrosting and 59.4% of the supplied energy was used for melting frost. The maximum defrosting efficiency could be up to 60.1%.
KW - Air source heat pump
KW - Defrosting efficiency
KW - Energy consumption
KW - Experiment
KW - Heat supply
KW - Revere cycle defrost
UR - http://www.scopus.com/inward/record.url?scp=84856382592&partnerID=8YFLogxK
U2 - 10.1016/j.applthermaleng.2011.11.052
DO - 10.1016/j.applthermaleng.2011.11.052
M3 - Article
AN - SCOPUS:84856382592
SN - 1359-4311
VL - 37
SP - 380
EP - 387
JO - Applied Thermal Engineering
JF - Applied Thermal Engineering
ER -
