Condensation Pressure Drop Of R134a Research Articles

Experimental investigation on flow condensation pressure drop of R134a in microfin 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 microfin tube was experimentally 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 microfin tube. It can be found that the correlations of Cavallini et al., Han et al. and Haraguchi et al. show a good prediction effect with mean relative deviation (MRD) of 13.89, 16.08 and −2.19%, respectively. The 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 >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 <10% for R134a and R410A; therefore, it can be said the improved correlation has a good predictive result for the pressure drop.

Experimental investigation of condensation pressure drop of R134a in smooth and grooved multiport flat tubes of automotive heat exchanger

Condensation frictional pressure drop was obtained in multiport micro channel smooth and grooved flat tubes using R134a. The study consists of two smooth and one grooved tube. Refrigerant R134a is studied over a mass flux 490–1600 kg/m2s, heat flux 5.5–19 kW/m2 and saturation temperature 51–68 °C. Results reveal that frictional pressure drop increases with an increment of mass flux, vapor quality and decreases with the increase of saturation temperature. The effect of heat flux on frictional pressure drop was negligible. Grooved tube shows the lowest pressure drop and surprisingly highest heat transfer coefficient. The frictional pressure drop data was compared with famous correlations. Zhang and Webb predicted 86% of the data with in ±30%.

Condensation pressure drop of R22, R134a and R410A in a single circular microtube

The condensation pressure drop characteristics for pure refrigerants R22, R134a, and a binary refrigerant mixture R410A without lubricating oil in a single circular microtube were investigated experimentally. The test section consists of 1,220 mm length with horizontal copper tube of 3.38 mm outer diameter and 1.77 mm inner diameter. The experiments were conducted at refrigerant mass flux of 450–1,050 kg/m2s, and saturation temperature of 40°C. The main experimental results showed that the condensation pressure drop of R134a is higher than that of R22 and R410A for the same mass flux. The experimental data were compared against 14 two-phase pressure drop correlations. A new pressure drop model that is based on a superposition model for refrigerants condensing in the single circular tube is presented.