EXPERIMENTAL STUDY ON SUBCOOLED FLOW BOILING CHARACTERISTICS OF R134a IN HORIZONTAL HELICALLY-COILED TUBES

摘要

An experimental study was performed to investigate the subcooled flow boiling characteristics of R134a in a horizontal helically-coiled tube at low mass flux, low pressure and constant heat-flux conditions. The experimental parameters are pressures of 0.412～0.653MPa, heat fluxes of 0.11～10.9kW/m~2, mass fluxes of 147～249kg/m~2s and inlet subcooled temperatures of 6.0～11.0℃. The variation of wall temperatures at different positions on the circumference of the test sections, the heat transfer coefficients and the effect of heat-flux, mass flux and inlet subcooled temperature on the subcooled flow boiling were discussed in detail. A new correlation was developed to predict the heat transfer coefficients for subcooled flow boiling of R134a in horizontal helically-coiled tubes.