Separation of Liquid and Vapor in Header of MCHE

This paper presents the experimental study of separation of two-phase flow in a vertical header of microchannel heat exchanger (MCHE) based on quantified visualization using fast camera, modelling analysis and experimental evaluation. A condenser model is developed to explore separation effects on heat exchanger. The modeling results show the benefits that a separation condenser has over a conventional condenser is affected by the separation results in the header. A header prototype is made that has an inlet in the longitudinal center part. Two sub-passes downstream are incorporated, lower for liquid and upper vapor flow. The header for experiment is clear to provide visual access. R-134a is used as the fluid of interest and mass flux through the inlet microchannels is controlled between 55 kg/(m2s)-195 kg/(m2s). The experiment results indicate that ideal separation in that header can happen at low mass flux up to 70 kg/(m2s). Results are presented in function of liquid and vapor separation efficiencies (ηl, ηv). Two phase flow inside the header is analyzed to study the mechanisms for liquid-vapor separation.