An empirical model for sizing capillary tubes

This paper presents an empirical model that has been developed to size adiabatic and non-adiabatic capillary tubes for small vapour compression refrigeration systems, in particular, household refrigerators and freezers. The model is based on the assumption that the length of a capillary tube is dependent on five primary variables, namely the capillary tube inner diameter, the mass flow rate of the refrigerant in the capillary tube, the pressure difference between highside and lowside, the refrigerant subcooling at capillary inlet and the relative roughness of the capillary tube material. The model is validated with previous studies over a range of operating conditions and is found to agree reasonably well with the experimental data for HFC134a. Copyright (C) 1996 Elsevier Science Ltd and IIR