Condensation heat transfer of a pure fluid and binary mixture outside a bundle of smooth horizontal tubes. Comparison of experimental results and a classical model

2001 ◽  
Vol 24 (8) ◽  
pp. 841-855 ◽  
Author(s):  
M. Belghazi ◽  
A. Bontemps ◽  
J.C. Signe ◽  
C. Marvillet
Keyword(s):  
Heat Transfer ◽  
Binary Mixture ◽  
Classical Model ◽  
Experimental Results ◽  
Condensation Heat Transfer ◽  
Horizontal Tubes ◽  
Pure Fluid

Research on R245fa Condensation Heat Transfer Characteristic Inside Horizontal Tubes

2016 ◽  
Author(s):  
Shengchun Liu ◽  
Wenkai Zhang ◽  
Ziteng Dong
Keyword(s):  
Heat Transfer ◽  
High Efficiency ◽  
Transfer Characteristic ◽  
Condensation Heat Transfer ◽  
Two Phase ◽  
Horizontal Tubes ◽  
Copper Pipe ◽  
Practical Engineering ◽  
Inner Diameter ◽  
Condensation Heat Transfer Coefficient

Condensation heat transfer of R245fa in horizontal copper pipe is studied in this paper. In the experimental study, the pipe inner diameter is 4.38 mm, the condensing temperature range from 50∼60°C, mass flow rate ranges from 3.132kg/h to 11.988kg/h, and inlet ranges from 0.89∼1. The research results indicate that the condensation coefficient is rose with the condensing; and it will rise when the inlet quality ranges from 0.89 to 1. Experimental value and the existing two-phase flow correlation are compared in this paper. It shows that the condensation heat transfer coefficient predicted by Haraguchi correlation has a high accuracy relatively. The research provides a foundation to promote development of microchannel high efficiency heat exchanger and it is useful to practical engineering.

Effect of Surface-Free-Energy-Difference on Condensation Characteristic Curves of Binary Mixture of Steam and Ethanol Vapor

2006 ◽  
Author(s):  
Xue-Hu Ma ◽  
Zhong Lan ◽  
Xing-Dong Zhou ◽  
Yu Zhang
Keyword(s):  
Heat Transfer ◽  
Free Energy ◽  
Binary Mixture ◽  
Surface Free Energy ◽  
Ethanol Vapor ◽  
Energy Difference ◽  
Heat Transfer Process ◽  
Condensation Heat Transfer ◽  
Free Energy Difference ◽  
Operation Conditions

The condensation heat transfer process of binary mixture of steam and ethanol vapor was studied experimentally with various ethanol concentrations and surface subcooling at atmospheric pressure. The experiments demonstrate that the condensation modes alter from filmwise, to transition and finally to dropwise with respect to the operation conditions. The marangoni effect was always used to interpret this phenomenon in the published literature. In this paper, the mechanism of condensation heat transfer with the liquid-solid-surface-free-energy-difference is used to further understand this process and the conversion of condensation modes. From this viewpoint, the condensation characteristics of binary mixture of steam and ethanol vapor can be explained reasonably with the corresponding condensation modes. Base on the data of the present paper and those reported in literature, the conversion criterion of the condensation modes is proposed. The condensation state is filmwise for the surface-free-energy-difference less than 14±1 mJ·m−2 and dropwise for more than 21±1 mJ·m−2 and transition for between 14±1 mJ·m−2 and 21±1 mJ·m−2.

Measurement of Condensation Heat Transfer Coefficients at Near-Critical Pressures in Refrigerant Blends

2006 ◽  
Vol 129 (8) ◽  
pp. 958-965 ◽  
Author(s):  
Yirong Jiang ◽  
Biswajit Mitra ◽  
Srinivas Garimella ◽  
Ulf C. Andresen
Keyword(s):  
Heat Transfer ◽  
Mass Flux ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Condensation Heat Transfer ◽  
Liquid Region ◽  
Transfer Coefficients ◽  
Reduced Pressure ◽  
Heat Transfer Coefficients ◽  
Horizontal Tubes

This paper presents the results of an experimental study on condensation heat transfer of refrigerant blends R404A and R410A flowing through horizontal tubes of 9.4 and 6.2mm inner diameter at nominal pressures of 80% and 90% of the critical pressure. Local heat transfer coefficients were measured for the mass flux range 200<G<800kg∕m2‐s in small quality increments over the entire vapor-liquid region. Heat transfer coefficients increased with quality and mass flux, while the effect of reduced pressure was not very significant within this range of pressures. The heat transfer coefficients increased with a decrease in diameter.

Experimental Study on Free-Convection Condensation Heat Transfer From Moist Air

2005 ◽  
Author(s):  
Niro Nagai ◽  
Masanori Takeuchi ◽  
Osamu Kura ◽  
Tomoharu Masuda
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Inclination Angle ◽  
Pressure Ratio ◽  
Film Theory ◽  
Experimental Results ◽  
Condensation Heat Transfer ◽  
Moist Air ◽  
Transfer Coefficients ◽  
Experimental Conditions

Characteristics of free-convection condensation heat transfer from moist air under atmospheric pressure were experimentally investigated, for further improvement of physical modeling on heat and mass transfer of solar distillation device. The cooled metal surface was 50mm width × 100mm height. The experimental conditions were as follows. Moist air temperature range was 40∼100°C for saturated moist air, and 50∼70°C for non-saturated moist air. Relative humidity range was 50∼90%. Inclination angle of cooled surface was 0° (downward facing) ∼ 180° (upward facing). All experimental results of heat transfer characteristics for vertical surface (angle 90°) were well correlated into a single equation with partial air pressure ratio using classical Nusselt’s liquid-film theory. The experimental results for the effects of inclination angle show that heat transfer coefficients for angle 0°∼105° were almost constant with slight peak value at angle 45°, followed by rapid decreasing of heat transfer coefficient over angle 120°.

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