Experimental study on R-600a boiling in 2.6 mm tube

Boiling heat transfer of R-600a in a 2.6 mm ID tube was investigated. Experimental conditions comprised heat fluxes of 44–95 kW m−2, mass velocities of 240 and 440 kg m−2 s−1 and saturation temperature of 22 °C. The effect of heat flux on the heat transfer coefficient was significant at low vapor qualities for the lower mass velocity. Frictional pressure drops increased with vapor quality and mass velocity. In comparison with R-134a, R-600a provides higher heat transfer coefficients and pressure drops. For the prediction of the heat transfer coefficients, the correlation of Kandlikar and Balasubramanian (2004) best fitted the experimental results, through the adjustment of a model coefficient. For frictional pressure drops, deviations from results obtained by usual correlations were quite large. The present results extend the ranges of heat flux and mass velocity beyond those available in the literature for R-600a, and thus represent a substantial contribution to the theme.

► We performed an experimental study of flow boiling of R600a in a mini channel.
► The heat transfer coefficients for R-600a were higher than for R-134a.
► There was significant influence of heat flux on heat transfer coefficients.
► The frictional pressure drop increased with the increase in vapor quality and mass velocity.
► The results were compared to predictive methods from the literature.