Semi-Empirical Model and Experimental Verification of Scroll Compressor with Vapor Injection

To simulate and optimize an enhanced vapor-injection system, it is necessary to develop a vapor-injection scroll compressor model with fast calculation speed, high accuracy, good extrapolation accuracy, and few parameters for computation. However, existing models cannot meet these demands simultaneously. In this study, a physics-based explicit form semi-empirical model of a scroll compressor with vapor injection was developed to predict its mass flow rate, input power, and discharge temperature. In this model, the suction mass flow rate was derived by correcting the pressure ratio using the specific heat ratio and multiplying it by the quadratic function of frequency. The injection mass flow rate was based on the assumption of an isochoric mixing process and obtained by expanding the coefficients. The discharge flow rate was the sum of the suction and injection mass flow rates. The input power was based on the assumption of isentropic compression and corrected by pressure, and the discharge temperature model was based on the heat leakage factor. The model was validated based on experimental data, and the results showed that the model had a calculation speed of milliseconds, and was able to accurately predict the performance of the compressor, with the average deviations of the suction mass flow rate and discharge mass flow rate both within 2%, and the average deviations of the injection mass flow rate, input power, and discharge temperature within 5%, 3%, and 3 ℃, respectively. The model can provide reasonable results outside the range of fitted conditions, and the amount of data required for model fitting has been reduced by more than 50% compared to that of existing models.