An experimentally validated model for microchannel heat exchanger incorporating lubricant effect

• A heat exchanger model comprehensively considering lubricant effect was developed.
• An infrared thermography based method was integrated in the heat exchanger model.
• New model showed superiority over models that ignore or overly simplify lubricant effect.

This paper presents the further development of Li and Hrnjak's (2013) microchannel heat exchanger model which includes the thermodynamic and transport properties of refrigerant–oil mixture. Effect of lubricant is accounted in boiling heat transfer, pressure drop and refrigerant distribution. A newly proposed infrared thermography based method is implemented in the model to describe the liquid refrigerant distribution in the inlet header of the microchannel heat exchanger. The new model is validated against experimental results (R134a-PAG 46 oil) at various oil circulation ratios (0.1%–8.3%). Simulation results also indicate that lubricant addition improves refrigerant distribution which is in agreement with experiments and the infrared thermography based method enables the model capture lubricant effect on capacity more comprehensively.