Brower’s fog film model, according to Ghiaasiaan (2007).
Starts with the molar-flux based, Couette flow model of condensation from a
carrier gas:
where:
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HGI
|
Heat transfer coefficient of gas film
|
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TG
|
(average?) gas temperature
|
|
TI
|
Saturation temperature, at interface gas concentration.
|
|
HFI
|
Heat transfer coefficient of liquid film.
|
|
TF
|
(average?) liquid temperature
|
|
N”
|
Molar flux
|
|
hfg
|
Latent heat of condensation
|
where:
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K~GI
|
Mass transfer coefficient (molar basis)
|
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Xv,s
|
Mole fr of vapour at the surface of the liquid.
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Xv,G
|
Mole fr of vapour in the bulk gas.
|
Normal film models overpredict the condensation rate when
fog occurs. Brower’s model applies corrections to the above.
These correction factors are found using
the equations Browers developed:
where:
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Cpv
|
Heat capacity of vapour
|
|
Le
|
Lewis number , thermal diffusivity over mass diffusivity av/Dv,n.
|
|
ShGI
|
Sherwood number, mass transfer rate over diffusion rate KGI
pipe dia/ρGD12
|
|
NuGI
|
Nusselt number
|
|
F
|
F = Pv(T)/P. so I’m guessing, equilibrium vapour
pressure over total pressure, which would make it equilibrium mole fraction
by Raoult’s law. Which would make dF/dT]TI the gradient of this at
the gas/liquid interface.
|
REF
Ghiaasiaan, SH. 2007. Two phase flow,boiling and
condensation in conventional and miniature systems. Chambridge University
Press.
