Experimental study on pressure drop of R32, R152a and R22 during condensation in horizontal minichannels

• Pressure drops increase with increasing m and x.
• Pressure drops decease with increasing ts and channel diameter.
• Pressure drops in a square tube is larger than in a circular tube.
• R32 and R152a are good substitutes for R22 in light of condensation pressure drop.

The pressure drop characteristics of R32, R152a and R22 during condensation were experimentally investigated in a circular (dh = 1.152 mm) and two square (dh = 0.952 and 1.304 mm) horizontal minichannels. The experiments used saturation temperatures from 30 °C to 50 °C, mass fluxes from 200 to 800 kg/(m2 s) and vapor qualities from 0.1 to 0.9. The experiments investigated the effects of the flow conditions (mass flux, vapor quality and saturation temperature), the channel diameter, the channel geometry and the thermophysical properties on the pressure drops. The results show that pressure drops increase with increasing mass flux and vapor quality and decreasing saturation temperature and channel diameter. The friction pressure drops are not sensitive to the coolant condition. The study shows that R32 and R152a are good substitutes for R22 based on the pressure drop characteristics during condensation. Three pressure drop correlations in the open literature were used to predict the data in this study. The deviation of 73% predictions by Kim and Mudawar correlation on the data were within ±30%. Kim and Mudawar correlation best predicted the experimental data.