Microchannel heat exchanger, modeling, lubricant effect
In the microchannel heat exchanger model that is developed in this study, the thermodynamic and transport properties of refrigerant-oil mixture are taken into account as well as their impact on boiling heat transfer and pressure drop. This model is validated against experimental results (R134a-PAG 46 oil) at various oil circulation rates (0.1%-8.3%). The agreement between measurement and prediction is ±4% for capacity, ±10% for pressure drop and ±3? for superheat at compressor inlet. Inclusion of lubricant in the new model has provided better prediction over models using pure refrigerant. Simulation results also indicate that lubricant addition improves refrigerant distribution, thus decreases the capacity degradation due to maldistribution.