4277 -- Empirical Correlations for the Modeling of R-134a Flow Through Adiabatic Capillary Tubes PDF

This paper presents the results of an experimental study on capillary tubes commonly used as an expansion device in household refrigerators and freezers. The experiments were performed with the hydrofluorocarbon R-134a at different condensing pressures and levels of subcooling. The pressure and temperature profiles along the capillary tubes were measured in each test run. The data set was then used to evaluate the suitability of some equations previously reported in the literature for the single-phase friction factor, the underpressure of vaporization, and the entrance contraction loss factor. Correlations for the average and local two-phase friction factors were also developed based on the measured data.

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