|Title:||An Experimental Analysis of Cycling Losses in Domestic Refrigerator-Freezers
|Author(s):||Coulter, W.H.; Bullard, C.W.
|Abstract:||This report identifies and quantifies the cycling losses in a domestic refrigerator-freezer. During cycling
operation the refrigerator was found to operate between 5 and 25% less efficient then the corresponding quasisteady
machine. The cycling refrigerator operates with an evaporator capacity between 3 and 17% less than the
quasi-steady refrigerator, while at the same time requiring between 1 and 9% more power to operate.
This refrigerator performance degradation was attributed to several factors, the most important being the
refrigerant migration and the thermal mass of the evaporator and compressor. During the off-cycle refrigerant
migrates from the condenser to the evaporator as the system pressures equalize. The off-cycle migration increases
the temperature of the evaporator and necessitates refrigerant redistribution during the on-cycle, and thereby tends
to reduce system performance. The increased power requirements, traced to the compressor, result from slight
differences in system pressure and the reduced compressor efficiency due to a cool compressor.
With the cycling losses identified, several possible refrigerator design changes were suggested. It appears
that a refrigerator equipped with a reciprocating compressor, solenoid valves to isolate the condenser, and no
accumulator should operate in a nearly quasi-steady manner. In addition using the condenser fan to accelerate
charge redistribution was investigated. However, since the experimental refrigerator was equipped with an
accumulator which held up some charge manipulating the condenser fan showed little payoff.
|Publisher:||Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
|Series/Report:||Air Conditioning and Refrigeration Center TR-77
|Sponsor:||Air Conditioning and Refrigeration Center Project 30
|Date Available in IDEALS:||2009-04-17