It is necessary to establish a simple and accurate mathematical model of capillary tubesfor the study of the system performance of refrigeration appliances equipped with the capillary tube. In this work, a new general integral model of capillajry tubes has been presented. It covers subcooled, two--phase and superheated flow regions which may occur inthe capillary tube. In the different flow region, special approximate integral equation is developed. This model is used in prediction of mass flow rate of the refrigerants, R12, R134aand R600a flowing through the capillary tube. The results are compared with those of thedistribut ed-- p aramet er mo del. The average devtat ion is 1. 3 0 % and t he maximum deviationis +4.58/-6.39%. The computation speed of the recommended model is more than one orderof magnitude higher than that of the distributed-parameter one.
