Flow Characteristics of Refrigerants Inside Diabatic Capillary Tube

Abstract

In the present investigation, an attempt is made to develop a mathematical model of diabatic capillary tube. The mathematical model has been developed by using equations of conservation of mass, momentum and energy. We need to calculate both single phase and two phase length for predicting the length of diabatic capillary tube. Flow of refrigerants inside a capillary tube is a complex phenomenon and is further complicated by heat exchange region in case of diabatic capillary tube. The presence of heat exchange region causes a delay of vaporization. When the vaporization starts pressure falls sharply. Friction Factor also plays an important role in the pressure drop. Moody (1944) correlation is used to calculate the friction factor. McAdams et al. (1942) viscosity correlation has been used to evaluate the two phase viscosity of the refrigerant. Input parameters have been taken from the data of Mendoca et al. (1998). Further a geometric model is developed in Pro-E and the mesh is created in Ansys ICEM CFD and analysis is carried out in Ansys CFX which has three modules CFX-Pre, Solver and CFX-Post. Finally the results of mathematical model are validated with Ansys CFX and found to be in fair agreement.