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Taborek, J, xlv-lvi Taitel and Dukler flow regime map, for horizontal and inclined gas- liquid flows, Tamura et al correlation, for surface tension of mixtures, Taylor Forge method, for mechanical design of flanges, comparison with EN13445 method, Taylor series expansion, Teflon, use in heat transfer enhancement: TEMA (Tubular Exchanger Manufacturers Association): Temperature distribution: Tenders for heat exchangers, Terminal free fall velocity, in fluidization, Testing and inspection of heat exchangers: Tetrabromomethane: 1,1,2,2-Tetrachloroethane: Tetrachloroethylene: Tetradecane: Tetradecene: Tetrachlorodifluoroethane (Refrigerant 112): 1,1,1,2-Tetrafluoroethane (Refrigerant R134a): Tetrafluoromethane (Refrigerant 14): Tetrahydrofuran: 1,2,3,4-Tetramethylbenzene: 1,2,3,5-Tetramethylbenzene: 1,2,4,5-Tetramethylbenzene: Thermal conductivity: Thermal contact conductance (TCC), Thermal contact resistance (TCR), Thermal design, constructional features affecting, in shell-and-tube heat exchangers Thermal diffusivity: Thermal expansion coefficient: Thermal leakage in F-type shell-and-tube heat exchangers, Thermal mixing in plate heat exchangers, Thermal stress: Thermocal, heat transfer media, Thermodynamic cycles in refrigeration, Thermodynamic properties: Thermodynamic surface in radiative heat transfer, Thermoexel surface, for enhancement of boiling, Thermofluids, heat transfer medium, Thermosiphon Theta-NTU method: Thickness of boundary layers (displacement, momentum, energy, density, temperature), Thin-wall-type expansion bellows, Thiophene: Thome, J R Three-phase flows: Tie rods in shell-and-tube heat exchangers, Tinker method for shell-side heat transfer in shell-and-tube heat exchangers, Titanium and titanium alloys, T-junctions, loss coefficients in, Tolerances Toluene: m-Toluidine: Tong F-factor method, for critical heat flux with nonuniform heating, Tooth, A S, Total emissivity in gases, Transcendental equations in transient conduction, Transient behavior: Transition boiling: Transition flow, heat transfer in free convective flow over vertical surfaces in, Transitional flow, in combined free and forced convection,
Combined Free and Forced Convection in Passages with uniform heat flux, with uniform wall temperature,
Transmission of thermal radiation in solids: Transmissivity of solids: Transport properties: Transverse flow, combined free and forced convection in, Treated surfaces, for augmentation of heat transfer, Triangular duct: Triangular fins, in plate fin exchangers, Triangular relationship, in annular gas-liquid flow, Tribromomethane: 1,1,1-Trichloroethane (Refrigerant 140a): Trichloroethylene: Trichlorofluoromethane (Refrigerant 11) Trichloromethane (Chloroform) (Refrigerant 20): 1,1,2-Trichlorotrifluoroethane (Refrigerant 113): Tridecane: Tridecene: Triethylamine: 1,1,1-Trifluoroethane (Refrigerant 143a): Trifluoromethane (Refrigerant 23): Trimethylamine: 1,2,3-Trimethylbenzene: 1,2,4-Trimethylbenzene: 1,3,5-Trimethylbenzene: 2,2,4-Trimethylpentane (Isooctane): Triphenylmethane: Triple interface (gas/solid/liquid), True temperature difference, in double pipe exchangers, Truelove, J S, Tsotsas, E Tube-baffle damage, in heat exchangers, Tube banks, finned: Tube banks, plain: Tube banks, roughened tubes, effect of roughness on Euler number in, Tube bundles: Tube counts, in shell-and-tube heat exchangers: Tube end attachment, in shell-and-tube heat exchangers, Tube inserts, heat exchangers with, Tube-in-plate extended surface configurations, fin efficiency of, Tube plates, in shell-and-tube heat exchangers: Tube rupture in shell-and-tube heat exchangers, Tube-to-tubesheet attachment, in shell-and-tube heat exchangers, Tubes: Tucker, R J, Tunnel dryer, Turbine exhaust condensers: Turbines, lost work in Turbulence: Turbulent boundary layers: Turbulent buffeting, as source of tube vibration, Turbulent energy, integral equation for, Turbulent flow: Turnarounds, in heat exchangers, Turner, C W, Twisted tapes: Twisted tube heat exchangers, Twisted tubes Two-equation models, for turbulent boundary layers, Two-phase loop with capillary pump, Two-phase flows:

Index

HEDH
A B C D E F G H I J K L M N O P Q R S T
Taborek, J, xlv-lvi Taitel and Dukler flow regime map, for horizontal and inclined gas- liquid flows, Tamura et al correlation, for surface tension of mixtures, Taylor Forge method, for mechanical design of flanges, comparison with EN13445 method, Taylor series expansion, Teflon, use in heat transfer enhancement: TEMA (Tubular Exchanger Manufacturers Association): Temperature distribution: Tenders for heat exchangers, Terminal free fall velocity, in fluidization, Testing and inspection of heat exchangers: Tetrabromomethane: 1,1,2,2-Tetrachloroethane: Tetrachloroethylene: Tetradecane: Tetradecene: Tetrachlorodifluoroethane (Refrigerant 112): 1,1,1,2-Tetrafluoroethane (Refrigerant R134a): Tetrafluoromethane (Refrigerant 14): Tetrahydrofuran: 1,2,3,4-Tetramethylbenzene: 1,2,3,5-Tetramethylbenzene: 1,2,4,5-Tetramethylbenzene: Thermal conductivity: Thermal contact conductance (TCC), Thermal contact resistance (TCR), Thermal design, constructional features affecting, in shell-and-tube heat exchangers Thermal diffusivity: Thermal expansion coefficient: Thermal leakage in F-type shell-and-tube heat exchangers, Thermal mixing in plate heat exchangers, Thermal stress: Thermocal, heat transfer media, Thermodynamic cycles in refrigeration, Thermodynamic properties: Thermodynamic surface in radiative heat transfer, Thermoexel surface, for enhancement of boiling, Thermofluids, heat transfer medium, Thermosiphon Theta-NTU method: Thickness of boundary layers (displacement, momentum, energy, density, temperature), Thin-wall-type expansion bellows, Thiophene: Thome, J R Three-phase flows: Tie rods in shell-and-tube heat exchangers, Tinker method for shell-side heat transfer in shell-and-tube heat exchangers, Titanium and titanium alloys, T-junctions, loss coefficients in, Tolerances Toluene: m-Toluidine: Tong F-factor method, for critical heat flux with nonuniform heating, Tooth, A S, Total emissivity in gases, Transcendental equations in transient conduction, Transient behavior: Transition boiling: Transition flow, heat transfer in free convective flow over vertical surfaces in, Transitional flow, in combined free and forced convection,
Combined Free and Forced Convection in Passages with uniform heat flux, with uniform wall temperature,
Transmission of thermal radiation in solids: Transmissivity of solids: Transport properties: Transverse flow, combined free and forced convection in, Treated surfaces, for augmentation of heat transfer, Triangular duct: Triangular fins, in plate fin exchangers, Triangular relationship, in annular gas-liquid flow, Tribromomethane: 1,1,1-Trichloroethane (Refrigerant 140a): Trichloroethylene: Trichlorofluoromethane (Refrigerant 11) Trichloromethane (Chloroform) (Refrigerant 20): 1,1,2-Trichlorotrifluoroethane (Refrigerant 113): Tridecane: Tridecene: Triethylamine: 1,1,1-Trifluoroethane (Refrigerant 143a): Trifluoromethane (Refrigerant 23): Trimethylamine: 1,2,3-Trimethylbenzene: 1,2,4-Trimethylbenzene: 1,3,5-Trimethylbenzene: 2,2,4-Trimethylpentane (Isooctane): Triphenylmethane: Triple interface (gas/solid/liquid), True temperature difference, in double pipe exchangers, Truelove, J S, Tsotsas, E Tube-baffle damage, in heat exchangers, Tube banks, finned: Tube banks, plain: Tube banks, roughened tubes, effect of roughness on Euler number in, Tube bundles: Tube counts, in shell-and-tube heat exchangers: Tube end attachment, in shell-and-tube heat exchangers, Tube inserts, heat exchangers with, Tube-in-plate extended surface configurations, fin efficiency of, Tube plates, in shell-and-tube heat exchangers: Tube rupture in shell-and-tube heat exchangers, Tube-to-tubesheet attachment, in shell-and-tube heat exchangers, Tubes: Tucker, R J, Tunnel dryer, Turbine exhaust condensers: Turbines, lost work in Turbulence: Turbulent boundary layers: Turbulent buffeting, as source of tube vibration, Turbulent energy, integral equation for, Turbulent flow: Turnarounds, in heat exchangers, Turner, C W, Twisted tapes: Twisted tube heat exchangers, Twisted tubes Two-equation models, for turbulent boundary layers, Two-phase loop with capillary pump, Two-phase flows:
U V W X Y Z
T Transitional flow, in combined free and forced convection,
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Combined Free and Forced Convection in Passages

DOI 10.1615/hedhme.a.000177

2.5.10 Combined free and forced convection in passages

J. D. Jackson

General introduction

The term “combined forced and free convection” is used to describe the process of heat transfer in fluids where the flow field is modified significantly by the action of non-uniformity of gravitational body force as a consequence of the temperature dependence of fluid density. The influence of free convection is usually thought of in terms of the concept of fluid buoyancy. Another term commonly used to describe heat transfer under such conditions is “mixed convection”.

The effectiveness of heat transfer by forced convection as characterised by the Nusselt number NuF depends on Reynolds number and Prandtl number. In the case of free convection the corresponding parameter NuN depends on Grashof number and Prandtl number. Thus, for combined free and forced it is not surprising that Nusselt number depends on Reynolds number, Grashof number and Prandtl number.

In the early studies of convective heat transfer the forced and free convection modes were considered independently with only passing reference being made to any possible interaction between them. When combined free and forced convection did eventually begin to be investigated, attention was at first restricted to laminar and transitional flows. Later, it became clear that measurable influences of free convection could also be present in turbulent flows and that in some circumstances they were a dominant factor in determining the effectiveness of heat transfer under such conditions.

In the following review of combined free and forced convection in passages, attention is focussed on heat transfer in vertical and horizontal pipes. Clearly, the orientation of the pipe is an important parameter under conditions of buoyancy-influenced convective heat transfer. In the vertical case, the flow can be either aided by buoyancy (upward flow in a pipe with heating/ downward flow with cooling) or opposed by buoyancy (downward flow in a pipe with heating/upward flow with cooling). In the horizontal case buoyancy causes secondary, transverse motion to be superimposed on the axial flow. If a horizontal pipe is heated, the fluid tends to have an upward component of velocity over the sides and a downward component in the central region and the secondary flow pattern takes the form of two counterrotating vortices. Cooling, rather than heating, produces similar buoyancy-induced secondary circulation but with rotation in the opposite sense.

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