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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, 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, 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

Introduction

DOI 10.1615/hedhme.a.000381

3.21.1 Introduction

Section 178 outlines a number of passive and active methods for the enhancement of heat transfer, and this section will deal with one of the most commonly-used passive methods, the tube insert. Inserts are becoming more widely used in both single- and multi-phase applications, although are more prominent in the former. Of the various passive enhancement methods that are suitable for single-phase applications, displaced enhancement devices, swirl-flow devices, or hybrids of the two are in common use.

In two-fluid heat exchangers, it is the ratio of thermal resistances that will be of primary importance in determining to which side of the exchanger an enhancement method should be implemented in order to be of benefit. Enhancement is employed in order to reduce the controlling thermal resistance and thus improve the overall heat transfer coefficient across the interface. Consider, for the purpose of illustration, a shell-and-tube exchanger running water on the shell side and oil on the tubeside, with the heat transfer coefficients for the shell and tubeside being 2.5 and 0.5 kW/m2K, respectively. Assuming a thin tube wall with negligible resistance and no resistance due to fouling, the overall thermal resistance would be given by

\(\dfrac{1}{U}=\dfrac{1}{\alpha_i}+\dfrac{1}{\alpha_o}=2.0+0.4=\) 2.4 m2 K/kW

The proportion of the overall thermal resistance contributed by the tubeside would therefore be 2.0/2.4 = 83%. This system is clearly tubeside controlled, so would be a candidate for the use of tube inserts. Use of a shell side enhancement method (external fins, for example) would not have a significant impact on the overall heat transfer performance. Fundamentally, the use of any enhancement method serves to reduce the thermal resistance per unit length on the side of the exchanger in question. Any one of the following objectives may justify the use of tube inserts:

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