NOVEL MODELING APPROACH BASED ON FLOW QUALITY PREDICTION OF A TWO PHASE FLOW OF REFRIGERANT DURING EVAPORATION AND CONDENSATION

摘要

This paper presents a new modeling approach based on flow quality prediction of a two phase flow of refrigerant during evaporation and condensation. The current work considers the variation of thermodynamic and transport properties during the evolution of change of state process. The model will be implemented to predict the evaporator/condenser pressure drop and its impact on the heat exchanger size. A proposed equation for flow quality prediction is established accounting for pressure drop effects. Another flow quality prediction model is derived from the mass conservation equations using the mean velocity of liquid and vapor phases. Both methods showed a very high compatibility predicting up to 96% of the change of state processes. The proposed model for flow quality prediction has a limitation in predicting the last 4% of the evaporation process and this was justified as a mathematical restriction for flow quality higher than 96%.