Characteristics of an air source heat pump with novel photoelectric sensors during periodic frost–defrost cycles

Abstract To avoid mal-defrost phenomenon, an innovative photoelectric sensor is developed and presented in this paper. It is referred to as “Tube Encircled Photoelectric Sensor” (TEPS). Experiments are carried out in a controlled environmental chamber under standard frosting conditions. Ten TEPSs in 4 different models are tested on a commercial size air source heat pump with the nominal heating capacity of 60 kW. The characteristics of the air source heat pump, together with the performance of the TEPSs are investigated during 9 periodic frost–defrost cycles. Compared with the original defrosting control strategy equipped by the manufacturer, the proposed TEPS sensor reveals its potential ability to accurately control the defrosting process. Experimental results demonstrate that TEPSs can substantially prolong defrost intervals from 28.8 min to 52 min under the experimental conditions, and the number of defrost cycles can be reduced from 9 to 5. The performance improvement is found to be 6% to the heating efficiency, and 5% to the COP.

[1]  Sung Tack Ro,et al.  An experimental study of frost formation on a horizontal cylinder under cross flow , 2001 .

[2]  Giovanni Tanda,et al.  Study of free convection frost formation on a vertical plate , 2002 .

[3]  Bernard Franković,et al.  Prediction of an effective cooling output of the fin-and-tube heat exchanger under frosting conditions , 2009 .

[4]  Michael Wisniewski,et al.  The use of infrared thermal imaging in the study of ice nucleation and freezing of plants , 1998 .

[5]  Ju-Suk Byun,et al.  The application of photo-coupler for frost detecting in an air-source heat pump , 2006 .

[6]  Zhongliang Liu,et al.  An experimental study on minimizing frost deposition on a cold surface under natural convection conditions by use of a novel anti-frosting paint. Part II. Long-term performance, frost layer observation and mechanism analysis , 2006 .

[7]  Wei Wang,et al.  An experimental study of the correlation for predicting the frost height in applying the photoelectric technology , 2010 .

[8]  Jing Xiao,et al.  Field test investigation of the characteristics for the air source heat pump under two typical mal-defrost phenomena , 2011 .

[9]  Diogo L. da Silva,et al.  Experimental Study of Frost Accumulation on Fan-Supplied Tube-Fin Evaporators , 2011 .

[10]  Savvas A. Tassou,et al.  Frost formation and defrost control parameters for open multideck refrigerated food display cabinets , 2001 .

[11]  Wei Wang,et al.  An analysis of the feasibility and characteristics of photoelectric technique applied in defrost-control , 2009 .

[12]  Qingci Guo,et al.  A generalized simple model for predicting frost growth on cold flat plate. , 2012 .

[13]  D. S Llewelyn.  A significant advance in defrost control , 1984 .

[14]  V. D. Baxter,et al.  Field-measured cycling, frosting, and defrosting losses for a high-efficiency air-source heat pump , 1985 .

[15]  R. Morgan,et al.  Ice detection in heat pumps and coolers , 1978 .

[16]  Judith Evans,et al.  Refrigerant flow instability as a means to predict the need for defrosting the evaporator in a retail display freezer cabinet , 2008 .

[17]  Zhongliang Liu,et al.  An experimental study on minimizing frost deposition on a cold surface under natural convection conditions by use of a novel anti-frosting paint. Part I. Anti-frosting performance and comparison with the uncoated metallic surface , 2006 .

[18]  Xiaosong Zhang,et al.  Control strategy and experimental study on a novel defrosting method for air-source heat pump , 2010 .