Abstract:Recent work on improving general thermal design methods for condensation inside plain, horizontal tubes is presented, summarizing primarily the advances proposed at the Laboratory of Heat and Mass Transfer at the EPFL in collaboration with the University of Padova and the University of Pretoria. This work has focused on the development of a unified flow pattern, two-phase flow structure model for describing local heat transfer coefficients for pure fluids, azeotropic mixtures and zeotropic mixtures. Such metho… Show more
“…Since no experimental data of void fraction was obtained, the numerical results are compared with Rouhani-Axelsson void fraction correlation for horizontal flow (Thome, 2005). Table 2 shows that a reasonable agreement was obtained between the predicted average void fraction values and correlation results, especially for Cases 1 and 2.…”
“…Since no experimental data of void fraction was obtained, the numerical results are compared with Rouhani-Axelsson void fraction correlation for horizontal flow (Thome, 2005). Table 2 shows that a reasonable agreement was obtained between the predicted average void fraction values and correlation results, especially for Cases 1 and 2.…”
“…The theoretical results are determined using three of the most quoted predictive models, Shah, Cavallini and Thome [14]- [16]. These theoretical results are calculated by engineering equations solver (EES) software based on similar operating conditions and plotted with experimental results for comparison.…”
Section: Comparison Of Experimental and Predictive Models Resultsmentioning
An experimental investigation of refrigerant R-134a two-phase flow condensation heat transfer coefficient and pressure drop in condenser tube section of refrigeration system under different operating conditions is presented. The experimental and theoretical investigations are based on test conditions in range of 10 -17 kW/m 2 for heat flux, 42-63 kg/m 2 s for mass flux, vapor quality 1-0.03 and saturation temperature 44 to 49˚C. The experimental tests are conducted on test rig supplied with a test section to simulate the water cooled double pipe heat exchanger, which is designed and constructed in the present work. "The experimental results have revealed that, the heat flux and mass flux have significant impacts on the heat transfer coefficient. "The heat transfer coefficient was increased with increase in heat flux and mass flux at prescribed test conditions, where the enhancement in heat transfer coefficient was about 47% and 14% for relatively higher heat flux and mass flux, respectively. "The enhancement in the heat transfer coefficient was about 51% for relatively lower saturation temperature 45.97˚C and 43% for higher vapor quality 0.88 compared to other values at constant test conditions. "The pressure drop was higher in the range of 12% and 49% for relatively higher mass flux and heat flux respectively. "The present work results have validated by comparison with predictive models and with similar research work results and the comparison has revealed an acceptable agreement.
“…Review of the modern calculation methods for heat transfer coefficient and pressure drop in the condensation in conventional and minichannels was reviewed and discussed in [9]. Authors show the usefulness of Silver-Bell-Ghaly [17,3], Thome [18], and Cavallini et al [8] calculation methods. These methods are developed based on a mechanism of zeotropic mixtures flow condensation.…”
Analysis of the state of-the-art in research of refrigerant condensation in miniature heat exchangers, so-called multiports, was made. Results of refrigerant R407C condensation in a mini condenser made in the form of two bundles of tubular minichannels from stainless steel with an inside diameter 0.64 mm and length 100 mm have been presented. Two exchangers consisted of four minichannels and 8 minichannels have been investigated. The values of average heat transfer coefficient and frictional pressure drops throughout the condensation process were designated. The impact of the vapor quality of refrigerant and the mass flux density on the intensity of heat transfer and flow resistance were illustrated. A comparative analysis of test results for various refrigerants in both mini heat exchangers were made.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.