A condensation heat transfer correlation for inclined smooth tubes

Abstract

Correlation models for the prediction of condensation heat transfer performance of inclined smooth tubes are very scarce in literature. Most of the available models are limited to horizontal and vertical tube orientations. This paper presents a correlation model for the prediction of heat transfer coefficient during the convective condensation of R134a in a smooth inclined tube-in-tube condensing heat exchanger subject to diabatic conditions. The authors, in previous investigations presented the experimental data which have been used for the development of the proposed model. In this particular study, the test matrix comprises 260 data test points for inclination angles varying between -90 degrees (downward flow) and + 90 degrees (upward flow), for mass fluxes between 100 kg/m2s and 400 kg/m2s, mean vapour qualities between 0.1 and 0.9 at saturation temperature of 40°C. In the developed model, the effects of the independent variables such as mean vapour quality, mass flux and inclination are well captured. The proposed empirical model is in good agreement with the experimental data and performed better than the other models used for comparison.