Heat Transfer and Pressure Drop for Refrigerant R-12 Condensing in a Horizontal Tube

Abstract

The mechanism of heat transfer for refrigerant condensing in a horizontal tube is so complicated that no useful empirical equation has been reported. In this paper, experiments on condensing heat transfer and pressure drop for refrigerant R-12 (CF₂Cl₂) were made under various heat fluxes, mass flow rates of refrigerant and void fractions chosen as the main experimental parameters for three tube diameters.
The heat resistance governing heat transfer depends on the thickness of condensate wetting the tube surface and is determined mainly by the flow pattern and flow rate of refrigerant. The heat transfer coefficient varies with the condensing temperature when the flow pattern is laminar, and with the condensing pressure when the tube diameter is larger.
In conclusion, including the effect of the tube diameter, an empirical equation of condensing heat transfer accurate within a limit of ± 15% error was obtained, and a correlation by which condensing pressure drop can be estimated was worked out.