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Abstract

This paper presents the results from a numerical study on the local pressure distribution of some common traditional and alternative refrigerants flowing in adiabatic capillary tubes. The present model developed from the basic conservation law of mass, energy and momentum includes various relevant parameters. A homogeneous flow model is used in the two-phase flow region. Numerical results show that the alternative refrigerants used as examples in the present study consistently give higher pressure gradients than the traditional refrigerants.The present model can be used to simulate and compare the flow characteristics of the other refrigerants. It may be also an important tool for selecting the length of the capillary tube used in household refrigerators and freezers for given operating conditions.

A Study of the Flow through Capillary Tubes Tuned for a Cooling Circuit with Saturated Fluorocarbon Refrigerants

“…Some 18 capillary samples were investigated (ranging in ID from 0.6 to 1.1 mm and in length from 0.7 to 3 m). The four different friction factor approximations (Churchill [6], Colebrook [7], Haaland [25], and the classical equation) usually used in capillary flow models were compared with our measured results. Our evaluations resulted in a conclusion to use the Colebrook friction relation for our studies with a copper capillary, with an inner surface roughness selected to be around 2 × 10 −6 m. Differences between the correlations and experimental data are shown in Fig.…”

“…For instance, Bansal and Rupasinghe [6] and Kritsadathikarn et al [7] have presented models of homogeneous two-phase flow through an adiabatic capillary tube. Sami and Tribes [8] presented a numerical study of capillary tube performance, operating with alternative refrigerants and their binary mixtures.…”