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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
F-correction method: F-factor charts and equations for various heat exchanger configurations, F-factor method: F-type shells: Fabrication: Failure modes of heat exchangers, Falling films, direct contact heat transfer in, Falling film evaporator: Fanno flow, Fans in air-cooled heat exchangers: Fatigue as failure mode of a heat exchanger Fatigue life, of expansion bellows, Fawcett, R Fedor's method, for critical temperature, Fenghour, A Ferritic stainless steels, as material of construction, Fick's law for diffusion, Film boiling: Film model, condenser design by Film temperature, definition of for turbulent flow over flat plate, Films in heat exchangers, Filmwise condensation: Fincotherm, heat transfer medium, Finite-difference equations: Finite difference methods: Finite-element methods: Fins (see also Extended surfaces): Fire-tube boiler, Fired heaters, Fires, room, radiation interaction phenomena in, Firsova, E V, Fixed beds: Fixed tubesheet, shell-and-tube exchangers: Flanges, mechanical design of in heat exchangers, Flash evaporation Flat absorber of thermal radiation, Flat heads: Flat plate: Flat reflector of thermal radiation, Floating head designs for shell-and-tube heat exchangers: Flooded type evaporator, in refrigeration, Flooding phenomena: Flow distribution: Flow-induced vibration, Flow regimes: Flow stream analysis method for segmentally baffled shell and tube heat exchangers, Flue gases, fouling by, Fluid elastic instability as source of flow-induced vibration, Fluid flow, lost work in, Fluid mechanics, Eulerian formulation for, Fluid-to-particle heat transfer in fluidized beds, Fluidized bed dryer: Fluidized bed gravity conveyors, Fluidized beds: Fluids: Fluorine: Fluorobenzene: Fluoroethane (Refrigerant 161): Fluoromethane (Refrigerant 41): Fluted tubes:
application in evaporators, in augmentation of condensation,
Condensation Enhancement
Flux method, for modeling radiation in furnaces, Flux relationships in heat exchangers, Fogging in condensation Food processing, fouling of heat exchangers in, Forced flow reboilers: Formaldehyde: Formamide: Formic acid: Forster and Zuber correlation for nucleate boiling, Fouling, Foam systems, heat transfer in, Four phase flows, examples, Fourier law for conduction Fourier number (Fo): Frames for plate heat exchangers, France, guide to national practice for mechanical design, Free convection: Free-fall velocity, of particles, Free-stream turbulence, effect on flow over cylinders, Freeze protection of air-cooled heat exchangers, Freezing, of condensate in condensers Fresnel relations in reflection of radiation, Fretting corrosion, Friction factor: Friction multipliers in gas-liquid flow: Friction velocity, definition, Friedel correlation for frictional pressure gradient in straight channels, Froude number: Fuels, properties of, Fuller, R K, Furan: Furfural: Furnaces: Fusion welding, of tubes into tubesheets in shell-and-tube heat exchangers,

Index

HEDH
A B C D E F
F-correction method: F-factor charts and equations for various heat exchanger configurations, F-factor method: F-type shells: Fabrication: Failure modes of heat exchangers, Falling films, direct contact heat transfer in, Falling film evaporator: Fanno flow, Fans in air-cooled heat exchangers: Fatigue as failure mode of a heat exchanger Fatigue life, of expansion bellows, Fawcett, R Fedor's method, for critical temperature, Fenghour, A Ferritic stainless steels, as material of construction, Fick's law for diffusion, Film boiling: Film model, condenser design by Film temperature, definition of for turbulent flow over flat plate, Films in heat exchangers, Filmwise condensation: Fincotherm, heat transfer medium, Finite-difference equations: Finite difference methods: Finite-element methods: Fins (see also Extended surfaces): Fire-tube boiler, Fired heaters, Fires, room, radiation interaction phenomena in, Firsova, E V, Fixed beds: Fixed tubesheet, shell-and-tube exchangers: Flanges, mechanical design of in heat exchangers, Flash evaporation Flat absorber of thermal radiation, Flat heads: Flat plate: Flat reflector of thermal radiation, Floating head designs for shell-and-tube heat exchangers: Flooded type evaporator, in refrigeration, Flooding phenomena: Flow distribution: Flow-induced vibration, Flow regimes: Flow stream analysis method for segmentally baffled shell and tube heat exchangers, Flue gases, fouling by, Fluid elastic instability as source of flow-induced vibration, Fluid flow, lost work in, Fluid mechanics, Eulerian formulation for, Fluid-to-particle heat transfer in fluidized beds, Fluidized bed dryer: Fluidized bed gravity conveyors, Fluidized beds: Fluids: Fluorine: Fluorobenzene: Fluoroethane (Refrigerant 161): Fluoromethane (Refrigerant 41): Fluted tubes:
application in evaporators, in augmentation of condensation,
Condensation Enhancement
Flux method, for modeling radiation in furnaces, Flux relationships in heat exchangers, Fogging in condensation Food processing, fouling of heat exchangers in, Forced flow reboilers: Formaldehyde: Formamide: Formic acid: Forster and Zuber correlation for nucleate boiling, Fouling, Foam systems, heat transfer in, Four phase flows, examples, Fourier law for conduction Fourier number (Fo): Frames for plate heat exchangers, France, guide to national practice for mechanical design, Free convection: Free-fall velocity, of particles, Free-stream turbulence, effect on flow over cylinders, Freeze protection of air-cooled heat exchangers, Freezing, of condensate in condensers Fresnel relations in reflection of radiation, Fretting corrosion, Friction factor: Friction multipliers in gas-liquid flow: Friction velocity, definition, Friedel correlation for frictional pressure gradient in straight channels, Froude number: Fuels, properties of, Fuller, R K, Furan: Furfural: Furnaces: Fusion welding, of tubes into tubesheets in shell-and-tube heat exchangers,
G H I J K L M N O P Q R S T U V W X Y Z
F Fluted tubes: 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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