Author : T Ramadevi and Pedamuthevi Vijayanand

In-tube two phase flow finds its applications in steam power plants, refrigeration and air conditioning, distillation and desalination units and transport of oil and slurry etc. The two phase flow is described by the parameters like mass flux, vapor quality and void fraction etc while the performance parameters of two phase flow are given by heat transfer coefficient and pressure drop. The salient feature of in-tube two phase flow is the formation of flow regimes, viz., stratified, slug, annular etc due to counter acting forces of gravity and vapor shear. The present paper focuses primarily on the development of test facility to evaluate the two phase heat transfer coefficient and pressure drop of refrigerants, R22, R134a and R407C at high pressures with a maximum pressure limit of 20 bar. Using the three refrigerants, performance parameters of two phase flow are studied in the pressure range of 10 – 16 bar. The CFD analysis is performed using commercial CFD software, FLUENT. The numerical model is developed by considering physical model of annular flow regime as 60-70% of heat exchanger length is occupied by annular flow. The pressure gradient and wall shear stress from CFD analysis is taken as input in the numerical model. It aims to develop a predictive procedure using CFD analysis for the prediction of flow regimes and pressure drop and subsequently develop numerical model for the prediction of heat transfer coefficient.

Keywords: Evaporator, Two Phase, Computational Fluid Dynamics (CFD, Pressure, Performance

Article published in International Journal of Advance Industrial Engineering, Vol.3, No.3 (Sept-2015)