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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: 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: 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,
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Problems with water cooling towers

DOI 10.1615/hedhme.a.000371

3.18.6 Problems with water cooling towers

This section is concerned with towers where waste heat is removed from cooling water by direct contact with atmospheric air. Such towers are described in Section 3.12 of HEDH, which also gives the basis of thermal design. Operational problems are discussed below, for large natural draught towers, described in Section 328, and for the usually smaller mechanical draught towers, described in Section 329.

A. Testing

Some general problems in the testing of heat exchangers are listed in Section 367J. Problems specific to water cooling towers are discussed in #%SECTION_3.12.6_A%#, which also deals with acceptance testing. The most difficult problem is to measure the velocity and temperature of the air at various locations, as it leaves the tower. Similar problems arise in the testing of air-cooled heat exchangers, as described in Section 368G, but with direct-contact cooling, the problem is made worse by the fact that the air at outlet is saturated with water vapour and contains droplets. In order to obtain a heat balance and check the thermal performance, it is necessary to determine the temperature and the increase in the enthalpy of the air at many points across the area where the air leaves the tower. In view of these difficulties, complete tests on water cooling towers are rare.

Water cooling towers are designed to give their specified performance under conditions when the wet and dry-bulb temperatures of the ambient air are so high that they are likely to be exceeded on only a few days per year. The manufacturer should be asked to supply performance curves which show the mean recooled water temperature at various flow rates and inlet temperatures of the water, with a wide range of atmospheric conditions. The performance of the tower can then be checked in Winter and Spring, and, if it is below what is expected, the cause can be investigated and rectified before the hot Summer weather reduces the performance of the tower. The most likely causes of poor performance are disintegration of the packing, maldistribution of the water and maldistribution of the air; the 2nd and 3rd of these are discussed in the next sub-sections.

B. Maldistribution of water

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