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Damage, sources of heat exchangers
Damkohler number:
Damping:
Davis and Anderson criterion, for onset of nucleate boiling,
Decal, heat transfer medium,
Decane:
1-Decanol:
1-Decene:
Degradation temperature, of polymers,
Demisters, wire mesh, for multistage flash evaporators,
Dengler and Addoms correlation, for forced convective heat transfer in two-phase flow,
Density:
Deposition of droplets in annular flow
Deposition in fouling,
Desalination plants:
Desuperheaters for use in association with evaporators,
Developing flow in ducts:
Dew-poin corrosion,
Diathermanous fluid,
1,1-Dibromoethane:
Dibromomethane:
1,2-Dibromotetrafluoroethane (Refrigerant 114B2):
Dibutylamine:
Dibutyl ether:
Dichloroacetic acid:
o-Dichlorobenzene:
Dichlorodifluoromethane (see Refrigerant 12)
1,1-Dichloroethane (Refrigerant 150a):
1,2-Dichloroethane (Refrigerant 150):
1,1-Dichloroethylene:
cis-1,2-Dichloroethylene:
trans-1,2-Dichloroethylene:
Dichlorofluoromethane (see Refrigerant 21)
Dichloromethane (Refrigerant 30):
1,2-Dichlorotetrafluoroethane (Refrigerant 114)
1,2,3-Dichlorotrifluoroethane (Refrigerant 123)
Dielectric constant, of water,
Diethylamine:
n,n-Diethylaniline:
Diethylene glycol:
Diethyl ether:
Diethyl ketone:
Diethylsulfide:
Differential condensation:
Differential formulations for nonisothermal gas radiation,
Differential resistance term in heat exchanger design,
Differential vector operators in heat conduction,
Diffraction models for radiative heat transfer from surfaces,
Diffuse surfaces, radiative heat transfer between,
Diffuse wall passages, radiative heat transfer in,
Diffusers, single-phase flow and pressure drop in,
Diffusion, in multi-component condensation,
n,n-Diffusion coefficients:
1,1-Difluoroethane (Refrigerant 152a):
Difluoromethane (Refrigerant 32):
Diiodomethane:
Diisobutylamine:
Diisopropylamine:
Diisopropylether:
Dimensional analysis:
Dimensionless groups:
Dimethylacetylene:
Dimethylamine:
Dimethylaniline:
2,2-Dimethylbutane:
2,3-Dimethylbutane:
1,1-Dimethylcyclopentane:
Dimethylether:
Dimethylketone:
2,2-Dimethylpropane (neopentane):
Dimethylsulfide:
Dimpled surfaces, heat exchangers with,
1,4-Dioxane:
Diphenyl:
Diphenylamine:
Diphenylether:
Diphenylmethane:
Dipropyl ether:
Diisopropyl ether:
Dipropyl ketone:
Direct contact heat exchangers
Direct contact heat transfer,
Direct numerical simulation, of turbulence,
Dirichlet boundary condition, finite difference method,
Dished heads:
Discretization in numerical analysis:
Disk-and-doughnut baffled heat exchangers,
Disks, free convective heat transfer from inclined,
Dispersants, for fouling control,
Dispersed flow (liquid-liquid),
Dissipation of turbulent energy,
Distillation:
Distribution:
Dittus-Boelter equation, for single-phase forced convective heat transfer,
Dividing flow, loss coefficients in,
Dodecane:
1-Dodecene:
Donohue method, for shell-side heat transfer in shell-and-tube heat exchangers,
Double-pipe heat exchangers:
Double segmental baffled heat exchangers,
Downward facing surfaces, free convective heat transfer from,
Downward flow in vertical tubes, flow patterns in gas/liquid,
Dowtherm A:
Dowtherm J:
Dowtherms, as heat transfer media,
Drag coefficient:
Drag force:
Drag reduction,
Drainage, of condensate,
Dreitser, G,
Drift flux model for two-phase flows,
Drogemuller, P,
Droplets:
Dropwise condensation
Dry wall desuperheating (in condensation),
Dryers:
Drying loft,
Drying rates, prediction of,
Dryout:
Ducts, single-phase fluid flow and pressure drop in,
Duplex stainless steels,
Durand correlation for heterogeneous conveyance in solid/liquid flow,
Dynamically stable foam,
Dyphyl, heat transfer media,
Dzyubenko, B,
Index
HEDH
A
B
C
D
Damage, sources of heat exchangers
Damkohler number:
Damping:
Davis and Anderson criterion, for onset of nucleate boiling,
Decal, heat transfer medium,
Decane:
1-Decanol:
1-Decene:
Degradation temperature, of polymers,
Demisters, wire mesh, for multistage flash evaporators,
Dengler and Addoms correlation, for forced convective heat transfer in two-phase flow,
Density:
Deposition of droplets in annular flow
Deposition in fouling,
Desalination plants:
Desuperheaters for use in association with evaporators,
Developing flow in ducts:
Dew-poin corrosion,
Diathermanous fluid,
1,1-Dibromoethane:
Dibromomethane:
1,2-Dibromotetrafluoroethane (Refrigerant 114B2):
Dibutylamine:
Dibutyl ether:
Dichloroacetic acid:
o-Dichlorobenzene:
Dichlorodifluoromethane (see Refrigerant 12)
1,1-Dichloroethane (Refrigerant 150a):
1,2-Dichloroethane (Refrigerant 150):
1,1-Dichloroethylene:
cis-1,2-Dichloroethylene:
trans-1,2-Dichloroethylene:
Dichlorofluoromethane (see Refrigerant 21)
Dichloromethane (Refrigerant 30):
1,2-Dichlorotetrafluoroethane (Refrigerant 114)
1,2,3-Dichlorotrifluoroethane (Refrigerant 123)
Dielectric constant, of water,
Diethylamine:
n,n-Diethylaniline:
Diethylene glycol:
Diethyl ether:
Diethyl ketone:
Diethylsulfide:
Differential condensation:
Differential formulations for nonisothermal gas radiation,
Differential resistance term in heat exchanger design,
Differential vector operators in heat conduction,
Diffraction models for radiative heat transfer from surfaces,
Diffuse surfaces, radiative heat transfer between,
Diffuse wall passages, radiative heat transfer in,
Diffusers, single-phase flow and pressure drop in,
Diffusion, in multi-component condensation,
n,n-Diffusion coefficients:
1,1-Difluoroethane (Refrigerant 152a):
Difluoromethane (Refrigerant 32):
Diiodomethane:
Diisobutylamine:
Diisopropylamine:
Diisopropylether:
Dimensional analysis:
Dimensionless groups:
Dimethylacetylene:
Dimethylamine:
Dimethylaniline:
2,2-Dimethylbutane:
2,3-Dimethylbutane:
1,1-Dimethylcyclopentane:
Dimethylether:
Dimethylketone:
2,2-Dimethylpropane (neopentane):
Dimethylsulfide:
Dimpled surfaces, heat exchangers with,
1,4-Dioxane:
Diphenyl:
Diphenylamine:
Diphenylether:
Diphenylmethane:
Dipropyl ether:
Diisopropyl ether:
Dipropyl ketone:
Direct contact heat exchangers
Direct contact heat transfer,
Direct numerical simulation, of turbulence,
Dirichlet boundary condition, finite difference method,
Dished heads:
Discretization in numerical analysis:
Disk-and-doughnut baffled heat exchangers,
Disks, free convective heat transfer from inclined,
Dispersants, for fouling control,
Dispersed flow (liquid-liquid),
Dissipation of turbulent energy,
Distillation:
Distribution:
Dittus-Boelter equation, for single-phase forced convective heat transfer,
Dividing flow, loss coefficients in,
Dodecane:
1-Dodecene:
Donohue method, for shell-side heat transfer in shell-and-tube heat exchangers,
Double-pipe heat exchangers:
Double segmental baffled heat exchangers,
Downward facing surfaces, free convective heat transfer from,
Downward flow in vertical tubes, flow patterns in gas/liquid,
Dowtherm A:
Dowtherm J:
Dowtherms, as heat transfer media,
Drag coefficient:
Drag force:
Drag reduction,
Drainage, of condensate,
Dreitser, G,
Drift flux model for two-phase flows,
Drogemuller, P,
Droplets:
Dropwise condensation
Dry wall desuperheating (in condensation),
Dryers:
Drying loft,
Drying rates, prediction of,
Dryout:
Ducts, single-phase fluid flow and pressure drop in,
Duplex stainless steels,
Durand correlation for heterogeneous conveyance in solid/liquid flow,
Dynamically stable foam,
Dyphyl, heat transfer media,
Dzyubenko, B,
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
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Introduction and Fundamentals
DOI 10.1615/hedhme.a.000153
2.3.1 Introduction and fundamentals
G. F. Hewitt
A. Classification of multiphase flows
Surveys carried out on industrial heat exchanger systems have indicated that more than half of these involve multiphase flow in one form or another. Multiphase flow’s are ubiquitous in the power generation and process industries and have a very wide range of applications. Such flows are often extremely complex in nature and it should be stated at the outset that many of the relationships used for multiphase flows are of an essentially empirical nature, are of limited applicability, and reflect the poor physical understanding of many two-phase flow phenomena.
This part of the handbook deals with a variety of multiphase flows in which the phases passing through the system may be solid (denoted by the subscript s), liquid (denoted by ℓ ), or gas 1 (denoted by g ). Some of the characteristic features associated with the behavior of each of these phases in multiphase flows are as follows:
- Solids: Normally, the solid phase is in the form of lumps or particles. To all intents and purposes, the solid phase can be regarded as incompressible and to have a nondeformable interface with the fluid phase or phases with which it is flowing. The flow characteristics are strongly dependent on the size of the individual solid elements and on the motions of the associated fluids. Very small particles follow the fluid motions whereas larger particles are less responsive to turbulent eddies in the fluid. Normally, the size is nonuniform and a knowledge of the particle size distribution is of great significance in studying such flows. More often than not, the solid is denser than the associated fluid phases and, in horizontal flow systems, this can give rise to gravitational separation or stratification. Solid particles may adhere to channel walls as permanent fouling layers, and these layers can often be very significant resistances to heat transfer. Examples here would be the deposition of magnetite particles on the tubes of a boiler or deposition of crystalline solids in a cooler crystallizer.
- Liquid: In multiphase flows containing a liquid phase, the liquid can be the continuous phase, containing dispersed elements of solids (particles), gases (bubbles), or other liquids (drops). The liquid phase can also be discontinuous, for example, in the form of drops suspended in a gas phase or in another liquid phase. With the exception of some special kinds of non-Newtonian liquids, liquids differ greatly from solids in their response to deforming forces. In solids, provided the force is not too high, a small reversible deformation (elastic) occurs, allowing an equal and opposite force to be transmitted through the solid to balance the imposed force, if the solid is to remain at rest. As a fluid, a liquid does not have this property and a balancing force can only exist if the liquid is in motion. A liquid also differs from a solid insofar as its interface with other fluids (gases or other liquids) is readily deformable. The existence of interfacial tension (which may be regarded as the energy required to form a unit area of interface) tends to limit the deformation. For example, there is a tendency to form spherical droplets when the liquid is the discontinuous phase, such droplets representing the minimum interfacial energy per unit volume of the liquid.
Another important property of liquid phases relates to wetting. When a liquid phase is in contact with a solid phase (such as the channel wall) and is adjacent to another phase which is also in contact with the wall, there exists at the wall a triple interface, and the angle subtended at this interface - Gas: As a fluid, a gas lias the same properties as a liquid in its response to forces. However, it has the important additional property of being (in comparison to liquids and solids) highly compressible. Notwithstanding this property, many multiphase flows containing gases can be treated as essentially incompressible, particularly if the pressure is reasonably high and the Mach number with respect to the gas phase is low (e.g., < 0.2).
Having made some general statements about the properties of the various phases that make up multiphase flows, the common forms of multiphase flow will now be considered and examples given of their applications.
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