Experimental investigation on flow condensation pressure drop of R134a inside the micro-fin tube at high mass flux

Abstract

To clarify the influencing mechanisms of the experimental condition and the tube structure on the pressure drop of heat transfer fluid, the two-phase flow condensation pressure drop of R134a inside the micro-fin tube was experimental studied at high mass flux, which is different from other conventional researches. The experimental result shows the pressure drop is proportional to mass flux and fin helical angle, and is inversely proportional to condensation temperature and coolant Reynolds number. Moreover, the experimental data of pressure drop was compared with the predicted value of some existing correlations for the micro-fin tube. It can be found that correlations of Cavallini et al, Han et al and Haraguchi et al show a good prediction effect with the mean relative deviation of 13.89%, 16.08% and -2.19%, respectively. Correlations of Pierre/0.053, Kedzierski et al and Choi et al all underestimate most of the experimental data of the pressure drop inside the tube, and their prediction deviations are greater than 10%. That is, the application effect of the separated flow model is better than that of the homogeneous flow model. Finally, the Kedzierski et al correlation was improved to realize a high-precision prediction of the fluid flow mechanism inside the tube. Because the prediction deviation of the improved correlation between the experimental value and the predicted value was greatly reduced, its prediction deviation is less than 10% for R134a and R410A, therefore, it can be say the improved correlation has a good predictive results for the pressure drop.