Experimental investigation on the heat transfer and pressure drop characteristics of R600a in a minichannel condenser with different inclined angles

Abstract

• The heat transfer and pressure drop of R600a in a compact condenser was studied. • The effect of inclined angle in both horizontal and vertical directions was analyzed. • The calculation method of logarithmic mean temperature difference was modified. • New heat transfer correlation was proposed with a mean average deviation of 9.8%. • New friction factor correlation was proposed with a mean average deviation of 7.3%. The condensation heat transfer and pressure drop characteristics of R600a in a multi-louvered fins compact heat exchanger were studied in detail. Experiments were carried out at saturation pressures from 530 to 620 kPa, mass fluxes from 25 to 41.25 kg∙(m 2 ∙s) −1 , air temperature from 25 to 35 °C and inclined angles from 0° to 180° in horizontal and vertical directions, respectively. The effects of mass flux, saturation pressure, air temperature, and inclined angle were analyzed and discussed. The results indicated that both heat transfer coefficient and pressure drop increased with the increase of mass flux and decreased with the increase of saturation pressure. Both heat transfer coefficient and pressure drop were significantly affected by the inclined angle, while the heat transfer capacity of the condenser was almost independent of the inclined angle. The experimental data were compared with several well-known condensation heat transfer models. Based on analysis results, the modified method to calculate the logarithmic average temperature difference was proposed. This predicted method could decrease the deviations of those models by 15%. In addition, the improved correlations for heat transfer and friction factor were proposed and predicted the present experimental data well with 90% of the data points within the bandwidth of ±15% and ±12%, respectively.