Modeling Capacity and Coefficient of Performance of a Refrigeration Compressor

摘要

A rather complex mathematical model of a running refrigeration or air-conditioning compressor has been developed. The model is capable of predicting capacity and coefficient of performance of a compressor with acceptable accuracy. The input data consists of over sixty variables such as dimensions and tolerances of major parts of the compressor, thermodynamic and fluid mechanic properties of a refrigerant, oil viscosity, as well as the torque, power, and energy efficiency characteristics of an electric motor. The model has four major parts. The first part is a model of flow of gas through the suction valve. The second part is a model of flow of gas through the discharge valve [1]. The third part is the model of the leakage of gas through the clearance between the cylinder and the piston. The fourth part is a model of electric motor torque and efficiency [3]. The loss of energy due to the viscous friction in bearings, and due to the viscous friction of the piston, is also considered. The model does not include gas pulsation in suction and discharge plenums and mufflers, and it does not include models of heat exchange in the condenser and in the evaporator. Instead, constant evaporating and condensing pressures are considered.