reciprocating compressor, domestic refrigeration, refrigeration system analysis
This paper presents a simulation model for the transient behavior of vapor compression refrigerating appliances subjected to on-off control patterns focusing on the reciprocating compressor. A detailed compressor model is put forward based on two sub-models: one for the compression cycle, which can predict the valve dynamics, heat transfer in the compression chamber and the pressure pulsations in mufflers, and the other for the compressor shell, which calculates the temperature and mass flow rate in components other than the compression chamber. The remaining components of the single-door frost-free refrigerator considered in this work (i.e. condenser, evaporator, refrigerated compartment) are modeled based on mass and energy balances considering each component as an even lump. The expansion device and the refrigerant charge sub-models are replaced by prescribed condenser subcooling and evaporator superheating degrees, respectively. The overall cycle simulation model was validated by comparing predictions for the compressor temperatures and mass flow rate, indicated power, power consumption and overall energy consumption with the experimental counterparts measured in a household refrigerator, whose components – including the compressor – were carefully instrumented with thermocouples and pressure transducers, and tested in a climate chamber with a strict control of air temperature, humidity and velocity. Finally, sensitivity analyses were conducted to compare the effect of the compressor design parameters on its performance under calorimeter and actual system conditions.