Abstract
A simple physical model for small hermetic reciprocating, rotary and scroll compressors has been developed based on thermodynamic principles and large data sets from the compressor calorimeter and in situ tests. Pressure losses along the refrigerant path are neglected and a compression process is assumed isentropic. A mass flow rate model reflects clearance volumetric efficiency and simulates suction gas heating using an effectiveness method. Compressor work is calculated using the compressor efficiency represented by only two empirical parameters. A linear relationship between the discharge and shell temperatures is extracted from the large data sets and applied to the model for calculating the discharge temperature. Another experimental observation indicates that the specific volumes at the suction and discharge ports of the cylinder have linear relationships with the specific volumes at the compressor suction and discharge. Those relationships can be used for the compressor model and the possibility is reported. The models developed using physical principles and experimental observations can predict the mass flow rate and power consumption within ±3.0% accuracy.
