I am a PhD student, I use Fluent and I study a countercurrent evaporator with a return surface that will be used to cool a room.
the outside hot air is sucked through the Dry channel (bottom), a part is returned in the wet channel (above), in this channel it overhangs a film of water to cause evaporation and at the same time an exchange heat, which helps to reduce the air temperature in the dry channel and will be used for cooling the room.
my problem is in the part of the wet canal. Fluent does not consider the moisture content in the energy equation or in any other way does not take into account the evaporation phenomenon and mass transfer in this part.
Edit : we did the following steps:
General :
Type -> pressured-Based
Velocity formulation -> absolute
Time -> Steady
2D Space -> Planar
no Gravity
Models :
Multiphase (VOF) -> Evaporation-Condensation
3 Phases -> water, Vapor, Air
Energy : On
Viscous : Laminar
Species (Species Transport)
but the simulation didn't work
we have convergence but there is no mass transfer in the Wet Channel (Above). Fluent does not want to take into account the mass transfer of the water film to the ambient air of the wet channel and the temperature of the air in the wet channel is at the same temperature of the water.
and if we do not apply a temperature to the water, everything puts in the temperature of the Inlet (or almost).
Dear Djallel Abada
Although the problem is not well defined. Based on the information given, I can only suggest the followings:
Make sure you have enabled the mass-transfer mechanism (evaporation and condensation) and set all the parameters corresponding to it.
thanks Kuldeep Dagar :
we did the following steps:
General :
Type -> pressured-Based
Velocity formulation -> absolute
Time -> Steady
2D Space -> Planar
no Gravity
Models :
Multiphase (VOF) -> Evaporation-Condensation
3 Phases -> water, Vapor, Air
Energy : On
Viscous : Laminar
Species (Species Transport)
but the simulation didn't work
we have convergence but there is no mass transfer in the Wet Channel (Above). Fluent does not want to take into account the mass transfer of the water film to the ambient air of the wet channel and the temperature of the air in the wet channel is at the same temperature of the water.
and if we do not apply a temperature to the water, everything puts in the temperature of the Inlet (or almost).
Hi!
It seems that you have not included mass-transfer in the simulation. Species transport might not be suitable for your case.
You can follow the following steps:
1. Go to phase tab and click on interaction
2. Enable mass transfer mechanism and select evaporation and condensation (Refer attached figure)
Setup all the corresponding parameters according to the physics of your problem.
I calculate a steam boiler heat transfer by estimating the heat transfer on both the hot and cold fluid side. The boiling heat transfer coefficient is generally much higher than the other side. Once you have the value of total heat transferred, it is a simple matter of estimating the amount of vapour generated.
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