CRITICAL HEAT FLUX FOR BOILING FREON AT HIGH SUBCRITICAL PRESSURE IN HORIZONTAL TUBES.

Experimental data were obtained on the critical heat flux for the flow of boiling Freon 22 at high subcritical pressures in horizontal, uniformly heated tubes. The onset of the critical heat flux condition was always observed at the exit end of the tube. The critical heat flux generally varied along the perimeter of the horizontal tube, and it was the lowest at the top of the tube, its value being lower than that for the vertically upward flow. According mainly to the effects of both the exit quality and the mass velocity, the critical heat flux at the top of the tube, which was the primary critical heat flux in horizontal tubes, was classified into four characteristic regimes. A dimensionless correlation which predicted successfully the critical heat flux or the critical quality was developed for each regime.