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This paper presents the development and validation of a simulation model of an injection scroll compressor that can be used for optimization of a heat pump system for electric vehicles. The modeling considered the effects of refrigerant leakage and suction gas heating. The simulation model solved continuity and energy conservation equations using 4th Runge-Kutta scheme to predict the pressure and temperature variations according to scroll revolution. The refrigerant mass flow rate, compressor discharge temperature, and compressor power input were calculated. The results of the simulation model were validated with the experimental data. The simulation model predicted the compressor performance within ±10% deviation.

A residential heat pump faced with reliability problems due to high compressor discharge temperature and lower performance at lower ambient temperatures. Many researchers have been trying to overcome this problem by applying vapor injection techniques. However, the application of the vapor injection cycle caused higher cost due to the increased components such as internal heat exchanger or flash tank. Liquid injection technique has merits of cost and cycle reliability due to refrigerant that discharged from the condenser was expanded and injected directly into the compressor. In this study, a simulation program for a liquid injection heat pump cycle was developed. The performance of the cycle was simulated using a mass and energy balances. The model was validated by comparing the predictions with measured data at various operating conditions. Based on the simulation results, cycle performance characteristics were discussed at various operating and compressor design conditions using the simulation program.