185--Film Condensation of Pure Vapour

doi:10.1615/hedhme.a.000185

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Hagen-Poiseuille law Hagen-Rubens relation, between electrical and optical constants, Hall Taylor, N S, Halogenated hydrocarbons: Handley and Heggs equation for fixed bed pressure drop, Hankinson and Thomson method, for liquid density: Hardening (precipative) of stainless steels, Hardwick, R, Harris, D, Hausen equation for developing laminar flow, Hays, G F Headers in shell-and-tube heat exchangers, Heads, in heat exchangers: Heat and mass transfer: Heat exchanger design, introduction, Heat exchangers: Heat of vaporisation (see Enthalpy of vaporisation), of pure substances Heat pipes: Heat pumping, relation to heat exchanger network design, Heat storage (see Regenerators and thermal energy storage) entropy generation in, Heat transfer: Heat transfer coefficient: Heat transfer media, Heat transfer salt, Heat transfer regimes: Heat of vaporization, Heated cavity reflectometer, Heating media, for reboilers, Heavy water, physical properties of, Heggs, P J, Helical coils of circular cross section: Helical coils of rectangular cross section, Helical inserts, for enhancement of heat transfer in boiling, Helium: Helmholtz reciprocity principle, in radiative heat transfer, Henry, J A R, Henry-Fauske model, for critical two-phase flow, Henry's law, for partial pressure, Heptadecane: Heptadecene: Heptane: 1-Heptanol: 1-Heptene: Herman, K W, Hermes, C L L, Heterogeneous conveyance in horizontal pipes, Heterogeneous nucleation in boiling, Hewitt, G F Hexachloroethane (Refrigerant 116): Hexacyclopentane, superheated vapor properties, Hexadecane: Hexadecene: 1,5-Hexadiene: Hexagonal cells, in free convection, Hexamethylbenzene: Hexane: Hexanoic acid: 1-Hexanol: 1-Hexene: Hexylbenzene: Hexylcyclohexane: Hexylcyclopentane, Hicks equation, for fixed-bed pressure drop, High pressure closures, ASME VIII code guidance for, High-chrome steels, thermal and mechanical properties, High-finned tubes, correlations for single-phase heat transfer in flow over, Hills, P D Hohlraum cavity, Holdup, in liquid-liquid flow, Holland, guide to national practice for mechanical design of heat exchangers, Homogeneous condensation (fog formation), Homogeneous model: Homogeneous nucleation: Honeycombs: Hopkins, D, Horizontal condensers: Horizontal cylinders: Horizontal layers, of fluid, free convection heat transfer in, Horizontal pipes: Horizontal shell-side evaporator, Horizontal surfaces: Horizontal thermosiphon reboilers: Horizontal tube-side evaporator, Horizontal tubes:

boiling outside with crossflow, combined free and forced convection in, combined free and forced convective heat transfer from outside, condensation on inside

Film Condensation of Pure Vapour Heat Transfer annular flow, flow regimes stratifying flow

condensation on outside of convective boiling in, flow regimes in gas-liquid flow in, flow regimes in liquid-liquid flow in: free convective heat transfer from outside of, heat transfer to, in fluidized beds, hydrodynamics of various two-phase flow regimes in, pool boiling from,

Hottel's rule, in absorption of radiation by gases, Hsu criterion, for onset of nucleate boiling, Hybrid cooling towers, Hydraulic conveyance: Hydraulic expansion, of tubes into tube sheets in shell-and-tube heat exchangers, Hydraulic turbine, lost work in, Hydraulic resistance, in flow of supercritical fluids, Hydraulically smooth surface, Hydrazine: Hydrocarbons: Hydrodynamic entrance length, in single-phase flow in ducts, Hydrogen: Hydrogen bromide: Hydrogen chloride: Hydrogen cyanide: Hydrogen fluoride: Hydrogen iodide: Hydrogen peroxide: Hydrogen sulfide: Hydrostatic testing of shell-and-tube heat exchangers, Hysteresis:

Index

HEDH

A B C D E F G H

Hagen-Poiseuille law Hagen-Rubens relation, between electrical and optical constants, Hall Taylor, N S, Halogenated hydrocarbons: Handley and Heggs equation for fixed bed pressure drop, Hankinson and Thomson method, for liquid density: Hardening (precipative) of stainless steels, Hardwick, R, Harris, D, Hausen equation for developing laminar flow, Hays, G F Headers in shell-and-tube heat exchangers, Heads, in heat exchangers: Heat and mass transfer: Heat exchanger design, introduction, Heat exchangers: Heat of vaporisation (see Enthalpy of vaporisation), of pure substances Heat pipes: Heat pumping, relation to heat exchanger network design, Heat storage (see Regenerators and thermal energy storage) entropy generation in, Heat transfer: Heat transfer coefficient: Heat transfer media, Heat transfer salt, Heat transfer regimes: Heat of vaporization, Heated cavity reflectometer, Heating media, for reboilers, Heavy water, physical properties of, Heggs, P J, Helical coils of circular cross section: Helical coils of rectangular cross section, Helical inserts, for enhancement of heat transfer in boiling, Helium: Helmholtz reciprocity principle, in radiative heat transfer, Henry, J A R, Henry-Fauske model, for critical two-phase flow, Henry's law, for partial pressure, Heptadecane: Heptadecene: Heptane: 1-Heptanol: 1-Heptene: Herman, K W, Hermes, C L L, Heterogeneous conveyance in horizontal pipes, Heterogeneous nucleation in boiling, Hewitt, G F Hexachloroethane (Refrigerant 116): Hexacyclopentane, superheated vapor properties, Hexadecane: Hexadecene: 1,5-Hexadiene: Hexagonal cells, in free convection, Hexamethylbenzene: Hexane: Hexanoic acid: 1-Hexanol: 1-Hexene: Hexylbenzene: Hexylcyclohexane: Hexylcyclopentane, Hicks equation, for fixed-bed pressure drop, High pressure closures, ASME VIII code guidance for, High-chrome steels, thermal and mechanical properties, High-finned tubes, correlations for single-phase heat transfer in flow over, Hills, P D Hohlraum cavity, Holdup, in liquid-liquid flow, Holland, guide to national practice for mechanical design of heat exchangers, Homogeneous condensation (fog formation), Homogeneous model: Homogeneous nucleation: Honeycombs: Hopkins, D, Horizontal condensers: Horizontal cylinders: Horizontal layers, of fluid, free convection heat transfer in, Horizontal pipes: Horizontal shell-side evaporator, Horizontal surfaces: Horizontal thermosiphon reboilers: Horizontal tube-side evaporator, Horizontal tubes:

boiling outside with crossflow, combined free and forced convection in, combined free and forced convective heat transfer from outside, condensation on inside

Film Condensation of Pure Vapour Heat Transfer annular flow, flow regimes stratifying flow

condensation on outside of convective boiling in, flow regimes in gas-liquid flow in, flow regimes in liquid-liquid flow in: free convective heat transfer from outside of, heat transfer to, in fluidized beds, hydrodynamics of various two-phase flow regimes in, pool boiling from,

Hottel's rule, in absorption of radiation by gases, Hsu criterion, for onset of nucleate boiling, Hybrid cooling towers, Hydraulic conveyance: Hydraulic expansion, of tubes into tube sheets in shell-and-tube heat exchangers, Hydraulic turbine, lost work in, Hydraulic resistance, in flow of supercritical fluids, Hydraulically smooth surface, Hydrazine: Hydrocarbons: Hydrodynamic entrance length, in single-phase flow in ducts, Hydrogen: Hydrogen bromide: Hydrogen chloride: Hydrogen cyanide: Hydrogen fluoride: Hydrogen iodide: Hydrogen peroxide: Hydrogen sulfide: Hydrostatic testing of shell-and-tube heat exchangers, Hysteresis:

I J K L M N O P Q R S T U V W X Y Z

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Film Condensation of Pure Vapour

DOI 10.1615/hedhme.a.000185

2.6 CONDENSATION
2.6.2 Film Condensation of Pure Vapour

J. M. McNaught and D. Butterworth

A. Introduction

The various resistances to heat transfer during condensation are described in Section 184B. In condensation of a pure vapour, the main resistance is that of the film of condensate which forms on the cooled surface. With a laminar condensate film, heat transfer is by conduction so a thin film will give a lower resistance and therefore a higher heat transfer coefficient than a thick film. Turbulence in the film acts to increase the heat transfer coefficient. Vapour shear has the effect of thinning the film, inducing turbulence, and therefore of increasing the heat transfer coefficient. Other factors which affect the condensate heat transfer coefficient are waves on the film surface, droplet entrainment and deposition, condensate splashing, and condensate subcooling.

Section B provides methods for heat transfer with condensation on a vertical surface, which in a heat exchanger would normally be a vertical tube. Figure 1 illustrates condensation on a vertical surface when the vapour is considered to be stagnant and there is therefore no effect of vapour shear on the condensate film. The condensate drains vertically downwards under gravity, with a flowrate steadily increasing from zero at the top. At the very low film Reynolds numbers at the top of the surface the condensate flow is laminar and wave-free. At some point down the tube surface a transition occurs where waves form on the condensate film. This transition is due to instabilities at the vapour-liquid interface, and it can be characterised by the film Reynolds number. At a much higher Reynolds number there is a transition from laminar-type flow to turbulent flow. In the laminar region the heat transfer coefficient decreases as the Reynolds number increases. The rate of decrease becomes smaller in the laminar-wavy region because of the disturbances caused by the waves. In the turbulent region the higher effective viscosity causes the film to become thicker. However the overall effect in the turbulent region is that the heat transfer coefficient increases as the Reynolds number increases. This is because the increased convection due to turbulence more than compensates for the thickening film. Liquid metals can behave differently, as shown in Section F.

Figure 1 Condensation on a vertical surface in the absence of vapour shear

The effect of a downwards vapour velocity is to increase the heat transfer coefficient by both thinning the film and inducing turbulence (see Section B). An upward vapour velocity will tend to have the opposite effect. However a phenomenon known as flooding occurs before vapour velocities are high enough to affect heat transfer significantly. This phenomenon is where the upwards vapour flow prevents the condensate from draining from the bottom of the surface. This is discussed in Section B(e).

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