Experimental Study of Flow Boiling Heat Transfer of R30 in Microchannels

Abstract

Two-phase cooling technique including flow boiling heat transfer in microchannel is being widely applied in the mechanical and electronic devices, whereas most of the existing related studies still experiment with common coolants with low boiling points that are not suitable for extreme high-temperature heat dissipation. Thus the flow boiling heat transfer characteristics of R30 have been analyzed through an experiment in parallel microchannels with diameters of 0.5 and 1.0 mm. The experiment was performed under the following conditions: heat flux, ; mass flux, ; outlet vapor quality, 0–0.52. Results showed that the heat transfer coefficient is determined by heat flux and vapor quality in low-vapor-quality region dominated by nucleate boiling, and affected by vapor quality and mass flux in high-vapor-quality region dominated by convective boiling. Intermittent dryout occurs in the nucleate boiling region and is affected by mass flux resulting from the suppression of nucleate boiling. Higher mass flux can relieve the intermittent dryout and postpone the onset of the dryout incipience to higher vapor quality. Comparison with previous correlations showed their unsatisfactory accuracy on present data and implied relatively well heat transfer performance of R30.