Heat transfer and pressure drop during condensation of R152a in circular and square microchannels

The paper reports experimental data for heat transfer and pressure drop during condensation of R152a in circular and square microchannels with hydraulic diameters of 1.152 mm and 0.952 mm, respectively. Saturation temperatures are 40 °C and 50 °C with mass fluxes varying from 200 to 800 kg/m2 s and vapor mass qualities from 0.1 to 0.9. Effects of mass flux, vapor mass quality and channel geometry on heat transfer and pressure drop were investigated. The results show that heat-transfer coefficients and pressure drop both increase with increasing mass flux and vapor mass quality while decrease with increasing saturation temperature. Channel geometry has much effect on heat transfer at low mass fluxes while has little effect on pressure drop. The present data were compared with earlier empirical correlations and a theoretical solution. Heat transfer coefficients agree within experimental error with several correlations and a theoretical solution for both circular and square microchannels. One pressure drop correlation underestimates the data for the two microchannels while another pressure drop correlation overestimates the data for the square microchannel.