Two phase flow analysis of micro channel evaporator to investigate effect of geometry on pressure and heat transfer coefficient with respect to volume of fraction

Abstract Pressure and heat transfer coefficient (HTC) are parameters used to measure the performance of microchannel evaporators (MCE). By keeping the same overall dimensions, optimised hydraulic diameters of three different port shapes, square, rectangle and trapezoid, are analysed using CFD software to study the effect of geometry on the performance characteristics of MCE. The number of square, rectangle, and trapezoid channels is 580, 986, and 812, respectively. CFD analysis of the evaporator using R134a refrigerant is performed using the Volume of Fluid (VOF) with the SST k-ω model and Lee model for interphase mass transfer trace. Variation of pressure and HTC concerning volume of fraction liquid refrigerant (α) is compared for these three port structures. The trapezoid port microchannel evaporator (MCE) exhibits the highest pressure drop compared to square and rectangular port MCEs. The rectangular port MCE demonstrates the highest heat transfer coefficient among the configurations studied. The rectangular port MCE outperforms both square and trapezoid port MCEs in overall performance.