Pressure drop of R134a and R1234ze(E) flow boiling in microchannel arrays with single- and double-side heating

Abstract

An experimental study was carried out on two-phase pressure drop of R134a and R1234ze(E) flow boiling in glass microchannel arrays containing 50 parallel microchannels. Each channel has a hydraulic diameter of 301.6 μm, an aspect ratio of 2.46 and a length of 50 mm. Experimental conditions, including saturation temperatures of 26.7 °C, 29.1 °C and 31.3 °C, and mass fluxes of 50–250 kg/(m2 s), were taken into account. The effect of refrigerant properties, mass flux and saturation temperature on the flow boiling friction pressure drop were investigated. The two-phase friction pressure drop increases with increasing mass flux and decreasing saturation temperature. Specially, the effect of heating methods, including single-side heating and double-side heating, were experimentally evaluated. The two-phase friction pressure drop in microchannel arrays heated from both sides is higher than that with single-side heating. The experimental data was compared with two-phase friction pressure drop empirical correlations in the literature. The correlation provided by Zhang and Webb gives the best prediction of the experimental data with an average deviation of 34.27% for R134a and 16.88% for R1234ze(E). A new empirical correlation was provided based on the current experimental data, which could predict the current data with 94.5% prediction errors lower than 20%.