modeling, vapor injection, refrigeration, air conditioning, heat exchanger
The flash tank vapor injection cycle is widely used and has been proven effective for improving system performance compared with the conventional systems. A good control design for this type of cycle to make the system work properly under various operation conditions is a challenge and one often has to resort to experimental studies, which are time-consuming and costly. In this paper, a transient mathematical model for a flash tank vapor injection heat pump system with an economized scroll compressor is presented. The compressor model is a map-based model. The heat exchangers are modeled using the finite volume method. The valves are modeled using empirical correlations. The resulting equations are solved using a commercially available differential algebraic equation solver. The simulation results are compared against experimental data and the comparison indicates that the model can predict system transient behavior during startup reasonably well. Using this validated model, the impact of the upper-stage EEV opening is investigated.