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in augmentation of condensation
Condensation Enhancement
in augmentation of heat transfer, as enhancement device in boiling, completely rough surface, effect in flow in fixed beds, effect on flow over cylinders, effect on fouling, effect on pool boiling: critical heat flux, effect on pressure drop in tube banks, effect on skin friction in turbulent flow over flat plate, effect in transition flow over flat plate, radiative heat transfer from, values for commercial surfaces,
Rough walled passages, radiative heat transfer down, Rubber (sponge) balls, in fouling mitigation, Ryznar index for water quality,

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A B C D E F G H I J K L M N O P Q R
Rabas and Taborek correlation, for heat transfer in banks of low fin tubes, Rackett equation (modified) for liquid density Radiation: Radiation shields, in radiation heat transfer, Radiation source analysis, Radiative heat transfer: Radiators, automotive, construction, Radiometers, application in gas radiation property measurement, Radiosity, Stephan's law for, Radiosity-irradiation formulations in radiative heat transfer, Rankine cycle in refrigeration, Rao, B K Raoult's law for partial pressure, Rating of heat exchangers, Rayleigh instability, in free convection, Rayleigh number Reay, D Reboilers: Reciprocal mode integrating sphere, for reflection and transmission measurements in radiation, Rectangles: Rectangular ducts: Rectangular enclosures, free convective heat transfer in: Rectangular fins, for plate fin exchangers Reduced pressure, correlations for pool boiling using, Reference temperature: Refinery processes, fouling in, Reflection, of thermal radiation, from solid surfaces: Reflectivity, of solid surfaces, Reflectometer, heated cavity, Reflux condensers, Refractories, density of, Refractory surfaces, Refrigerants: Refrigerant 11 (Trichlorofluoromethane): Refrigerant 12 (Dichlorodifluoromethane): Refrigerant 13 (Chlorotrifluoromethane): Refrigerant 21 (Dichlorofluoromethane): Refrigerant 22 (Chlorodifluoromethane): Refrigerant 116: Refrigerant plant, entropy generation in, Refrigeration, heat transfer in, Regenerators and thermal energy storage, Regimes of heat transfer, in ducts, single phase flow, Reidel method, for predicting enthalpy of vaporisation, Reinforcing rings, for expansion bellows, Relaminarization, of turbulent flow, Reichenberg method, for effect of pressure on gas viscosity, Relief system design for shell-and-tube heat exchangers with tube side failure, Removal of fouling deposits: Renewable fuels, properties of, Renotherm, heat transfer medium, Repair, of expansion bellows, Residence times, in dryers: Resistance network analysis, Resistance (thermal) due to fouling: Reversible (minimum) work, in Reynolds number, Reynolds stress models, for turbulence, Rheologically complex materials, properties of: Rheological properties of drag reducing agents Rheology, shear flow experiments used in, Rhine, J M, Ribatski, G, Riblets for drag reduction, Richardson number, Richie, J M, Ring cells, in free convection, RODbaffles, in tube bundles with longitudinal flow, Rod bundles: Rohsenow correlation, for nucleate boiling, Roll cells, in free convection, Roller expansion, of tubes into tube sheets, Rose, J W, Rossby number, Rotary dryer, Rotating drums, heat transfer to particle bed in, Rotating surface, in an annular duct Rotation, as device for heat transfer augmentation, Roughness, surface:
in augmentation of condensation
Condensation Enhancement
in augmentation of heat transfer, as enhancement device in boiling, completely rough surface, effect in flow in fixed beds, effect on flow over cylinders, effect on fouling, effect on pool boiling: critical heat flux, effect on pressure drop in tube banks, effect on skin friction in turbulent flow over flat plate, effect in transition flow over flat plate, radiative heat transfer from, values for commercial surfaces,
Rough walled passages, radiative heat transfer down, Rubber (sponge) balls, in fouling mitigation, Ryznar index for water quality,
S T U V W X Y Z
R Roughness, surface: in augmentation of condensation
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Condensation Enhancement

DOI 10.1615/hedhme.a.000189

2.6 CONDENSATION
2.6.6 Condensation Enhancement

Ralph L. Webb

A. Introduction

Condensation will occur on a surface whose temperature is below the vapor saturation temperature. The condensed liquid formed on the surface will exist either as a wetted film or in droplets. The condensate forms as droplets on the surface, if the condensate does not wet the surface. Although dropwise condensation yields a very high heat transfer coefficient, it cannot be permanently sustained. Dropwise condensation (see Section 188) may be promoted by liquid additives or surface coatings that inhibit surface wetting. As the surface slowly oxidizes, the surface will eventually become wetted, and the process will revert to filmwise condensation (see Section 185). Hence, filmwise condensation is currently the more important process.

This section is concerned with enhancement of condensation. Geometries include plates and tubes (horizontal and vertical). Condensation may occur either inside or outside the tube. The condensation coefficient will be increased by surface or body forces, which act on the condensate film and reduce its thickness. Without special "enhancement" effects the film thickness on a stationary surface is influenced by gravity and interfacial shear stresses. Depending on the surface orientation, interfacial shear forces may aid or impede the gravity force.

The technology of enhancement of film condensation involves the following basic phenomena: (1) Additional surface forces, such as surface tension, to locally thin the film, (2) Additional body forces, such as electric fields or centrifugal force to pull the condensate off the surface, (3) Surface roughness tomix the condensate film. The effectiveness of these possible methods depends on the magnitude and direction of the imposed force, relative to the existing interfacial shear and gravity forces. The surface orientation and vapor velocity have a significant effect on the importance of the interfacial shear and gravity forces, respectively. Because the surface orientation and the number of forces that may act on the condensate film will affect the condensation coefficient, it is appropriate to segregate the discussion of enhancement into sub-sections, which depend on the surface orientation, vapor velocity, and the imposed enhancement techniques.

Because interfacial shear force may significantly alter the condensation coefficient, we will first address enhancement "without vapor shear" effects. Then, the survey will be concluded by geometries for which significant vapor shear effects exist. Vapor shear effects are important for both condensation inside tubes and on tube bundles.

1.4, = 4.742 and = 0.0. Again, this empirical correlation does not account for probable surface tension drainage effects or fin efficiency. However, it is probably the most general of those presented. The correlation predicted 71% of the data points within ± 30%.

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