Probabilistic flow pattern-based heat transfer correlation for condensing intermittent flow of refrigerants in smooth horizontal tubes

This paper presents a signal analysis method used for condensing refrigerants that results in a modification in the prediction method for heat transfer based on probabilistic time-fractional results. Development of an objective visual method for discrimination of flow patterns and determining probabilistic time-fractions in intermittent flow is presented. The frequency domain was identified as the main candidate for discrimination of sub-regimes present in intermittent flow. Experimental work was conducted using refrigerants R-22 and R-134a, at an average saturation temperature of image, with mass fluxes ranging from image, and with test section inlet vapour qualities ranging from 0.65 down to 0.10. These test conditions mostly represent intermittent flow. The new time fraction-corrected flow regime-based heat transfer correlation is heavily based on the Thome et al. (2003) correlation. The modified correlation predicted the experimental data with a mean absolute deviation of 10%.