|Title:||Development, Validation, and Application of a Refrigerator Simulation Model
|Author(s):||Woodall, R.J.; Bullard, C.W.
|Subject(s):||refrigerator systems analysis
|Abstract:||This report describes the further development and validation of the Refrigerator/Freezer
Simulation (RFSIM) model. The reports also describes the first major application of the model
as an analysis tool for new refrigerator designs; several aspects of multi-speed compressor
operation were examined with the model. Several improvements were made to the model that
facilitated the validation process and the examination of multi-speed compressors: the model was
made more general so that it could operate in numerous configurations in addition to the original
design and simulation modes; many improvements were made in the modeling logic and
robustness of the capillary tube-suction line heat exchanger model; and the equation-of-statebased
property routines that calculated the thermodynamic properties were replaced with
interpolation routines that were much faster. The RFSIM model, in design and simulation mode,
was validated with data from two refrigerators. In both modes, the average model errors were
less than ±5% for several important variables such as evaporator capacity and coefficient of
performance. The errors of the simulation mode were reduced from the previous model
validation primarily by using a different void fraction correlation in the refrigerant charge
equations. The results from the validated RFSIM model indicate that a two-speed compressor
could yield energy savings of 4% to 14% due to the increased steady-state efficiency at the low
speed and an additional 0.5 to 4% savings due to the decreased cycling frequency. The results
also showed that the capillary tube-suction line heat exchanger, when designed for the low speed,
did not adversely affect the pull-down capacity when the compressor operated at the high speed.
Lastly, it was found that a refrigerator operating at low ambient temperatures could actually
benefit from a decrease in the condenser fan speed. This change in fan speed increased the
evaporator capacity by reallocating charge to the evaporator and subsequently reducing the
superheat at the evaporator exit.
|Publisher:||Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
|Series/Report:||Air Conditioning and Refrigeration Center TR-99
|Sponsor:||Air Conditioning and Refrigeration Project 66
|Date Available in IDEALS:||2009-04-22