Investigation into the Phase Change of Refrigerant in a Wire–and–Tube Consender of Refrigerator

Abstract

During the passage of dhe refrigerant through the condenser of a refrigerator, it generally undergoes the processes of desuperheating, condensation and sub–cooling. One of dhe important criteria in condenser design is to locate the points where superheated refrigerant vapour changes to saturated vapour and subsequently from wet vapour to saturated liquid. The present paper discusses the analysis of wire–and–tube condenser under normal operating conditions of free convection using FEM where Galerkin’s weighted residual method is used to minimise the errors. Refrigerant R–134a is considered for the study and the condenser components are divided into several elements where the state of refrigerant is predicted. The effects of ambient temperature and mass flow rates of the refrigerant are also determined. This is used to find out the length of tube required for phase change for its initiation and completion. The methodology adopted is validated against dhe simulation data available in the literature for both sensible and latent heat transfer. The analysis also leads to the information about dhe adequacy of the number of tubes for complete condensation of the refrigerant vapour under given operating conditions. It is found that for a certain mass flow rate of refrigerant, sub–cooling does not occur at some higher ambient temperatures, thus showing the inefficiencies of the heat exchanger. The methodology can be used as a design tool for the design of wire–and–tube condenser of a small refrigerator. The derating of condenser under abnormal ambient conditions can also be predicted. Keywords: Wire-and-tube condenser, refrigerator, free convection, finite element method, phase change