The characteristics of boiling heat transfer and pressure drop of R-600a in a circular tube with porous inserts

This investigation was undertaken in order to better understand the characteristics of sub-cooled flow boiling heat transfer and pressure drop of a hydrocarbon refrigerant R600a (isobutane) flowing in a circular pipe within dispersed-copper porous inserts. The test was conducted at a saturation temperature of 10 °C, vapor qualities were from 0.076 to 0.87, and there was shown to be a mass flux of 120-1100 kg/m2 s and a heat flux of 12-65 kW/m2. The effects of Reynolds number and the sizes of inserts (the porosity, mean pore diameters and permeability) on the heat transfer and pressure drop of R-600a are presented. In addition, empirical correlations for estimating the boiling heat transfer coefficients and pressure drop for pure R-600a under these conditions have been proposed.