Heat Transfer Crisis in Subcooled Water Boiling in Macro-, Mini, and Microchannels

The paper presents the results of investigation into the crisis heat transfer in subcooled water boiling in macro-, mini-, and microchannels without coating and with porous coating. The equation for calculating the critical thermal load (CTL) in macro-, mini, and microchannels without coating is based on the analysis of arrays of experimental data obtained in investigating critical heat flux in subcooled water boiling in wide ranges of diameters, pressures, mass velocities and vapor contents. The calculation of the critical thermal load during boiling in a channel with porous coating has been conducted according to the previously developed formula for a horizontal 8-mm-diameter tube with a one-side heating. A porous coating in a macro-channel results in an almost threefold CTL rise. For a microchannel with a porous nanoparticle coating, CTL, at comparable mass velocities, is 1.5 times higher than without coating. The suggested equations for both channels without coating and channels with a porous coating describe the experimental data on critical thermal loads in macro-, mini-, and microchannels in the considered ranges of regime parameters with a deviation of no more than 30%.