NUMERICAL STUDY ON FLOW BOILING HEAT TRANSFER OF A REFRIGERANT MIXTURE IN HORIZONTAL TUBES UNDER A VARIED HEAT FLUX BOUNDARY CONDITION

A mathematical model has been developed to simulate the in-tube flow boiling heat transfer process of a refrigerant mixture under a variable heat flux boundary condition. The one-dimensional steady-state evaporation model is focused at a low heat flux and mass flow rate condition that is found in evaporator tubes of supermarket refrigerators and deep freezers. The governing equations are simplified to capture the physics of the stratified two-phase flow of the liquid and vapor phases during the boiling process. Finite volume formulation is used to solve the continuity, momentum, and energy equations. The present work is used to investigate the distributions of the temperature, heat transfer coefficient, heat flux, and void fraction of the refrigerant along the length of the evaporator tube. The simulation results from the model are verified with experimental results and the deviation is within acceptable limits.