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Old   January 31, 2003, 10:11
Default heat exchanger
  #1
Ghostrider
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Hi.

I want to simulate a counter flow heat exchanger. To do this would you create an annulus and subtract the inner pipe from the outer and then mesh the two pipes separately? And would you also set a wall between the pipes?

Thanx for your help,

Ghostrider
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Old   January 31, 2003, 12:16
Default Re: heat exchanger
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Eric R.
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Ghostrider,

I take it that you want to create a double-pipe HX'er, modelling conduction through the metal and convection in each fluid.

You will have to create three concentric cylinders, which creates 3 volumes when split correctly: volume inside inner pipe, volume of wall metal, and annulus volume of outer pipe. You probably want to use the "splitting tool" as opposed to the subtract tool, b/c subtract is often used to delete one portion of a volume from another. Good luck.

-Eric R.
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Old   January 31, 2003, 12:41
Default Re: heat exchanger
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mp
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hi Eric.

my problem is exactly the same.

but the inner pipe wall thickness is assumed to be very thin, hence, i define it as a wall boundary rather than creating a solid zone for conduction (conduction via pipe wall is assumed to be 100%). Therefore I have only two fluid zone volumes seperated by a thin wall.

my question is, how to model in Fluent, such kind of flow problems in which heat is transfered from the hot fluid to the cold fluid. How can I measure the heat transfer between the fluids? I am still hanging around. Any help would be greatly appreciated.

-mp
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Old   February 1, 2003, 14:02
Default Re: heat exchanger
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Eric R.
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Mp,

Your approach is fine, probably better than modelling the actual wall thickness. I am not exactly sure what you mean by asking how you can measure the heat transfer between fluids. You can have Fluent predict a variety of things, ie. temperature profile in each fluid, heat load, heat transfer coefficients, etc. You can get pretty much anything you'll need to define heat transfer.

Good luck.

-Eric
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Old   February 6, 2003, 06:13
Default Re: heat exchanger
  #5
mp
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Erik,

thanks for your reply, I am aware of the properties ie. temperature profile in each fluid, heat load, heat transfer coefficients, etc...

but my question is ...how can I initialize the solution....I would like to use massflow rate as input ( in the define/periodic conditions panel) for different Reynolds numbers. but it seems Fluent allows me to input massflow of only one of the fluids...then what about the other....i am confused... please help me....if you have any idea.

thanks and regards -mp
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