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Heating vertical liquid stream with parallel gas

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Old   May 5, 2023, 08:57
Default Heating vertical liquid stream with parallel gas
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Hello together,

I have a problem setting up a suitable model for the following task.

I want to heat a vertical free flowing liquid stream.
The stream is surrounded by a parallel hot gas flow i'm interested how much is the temperature rising in the liquid from the beginning of my observation area to the end (let's say 150mm).
The thing is, that I wanted to avoid models like VOF, because of the quite harsh gas flow conditions. I don't need atomization of the liquid or something like that. Only the rising temperature.

In my opinion,
my input parameters are mainly
- lquid flow rate (and/or stream diameter)
- liquid inlet temperature
- gas velocity and temperature surrounding the liquid

I'm quite clueless how to set up a reasonably plausible model.

Does someone has an idea how to do this?
And can I do this in a steady simulation?

If more informations are neede, just ask.

Thanks in advance
Tobi
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Old   May 8, 2023, 03:50
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Is the gas separated from the liquid by a wall or are they mixed within the "pipe"?
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Old   May 8, 2023, 07:51
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Thanks for the question.

The gas is not separated from the liquid in reality. And that's my problem.
So I would like to model the direkt heat transfer from gas to liquid.
Indeed, another approach could be to model a very thin pipe with nearly infinite heat transfer properties to separate the two phases. But I don't really like the idea and would test it only if I don't find any more suitable solution.

BR
Tobi


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Originally Posted by JBeilke View Post
Is the gas separated from the liquid by a wall or are they mixed within the "pipe"?
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Old   May 8, 2023, 09:30
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Why don't you want to use a multiphase approach? That's what I would try at first.
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Old   May 8, 2023, 18:42
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How is the liquid stream expected to look like or behave? - Just a vertical jet going down like from a kitchen tap or a garden hose?
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Old   May 15, 2023, 08:42
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Quote:
Originally Posted by JBeilke View Post
Why don't you want to use a multiphase approach? That's what I would try at first.
The thing is that the hot gas stream is, strictly speaking, a flame that makes contact with the liquid jet through circularly arranged burners. And as far as I know at the moment, it is not possible with Star CCM to carry out a two-phase simulation (liquid and gas --> VOF) and thereby model a combustion reaction in the gas phase in parallel. If that is possible, it might work. Alternatively, simplifications would be a possibility to avoid the combustion reactions.

Also, I am always open to other approaches.

BR
Tobias
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Old   May 15, 2023, 08:46
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Quote:
Originally Posted by cwl View Post
How is the liquid stream expected to look like or behave? - Just a vertical jet going down like from a kitchen tap or a garden hose?
The liquid behaves relatively laminar, although the gas flows are quite high (50m/s). This is mainly due to the high viscosity of the liquid. A slow-flowing jet from a water tap fits relatively well. However, with quite liquid honey

BR
Tobias
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Old   May 15, 2023, 09:04
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Quote:
Originally Posted by tohell92 View Post
The thing is that the hot gas stream is, strictly speaking, a flame that makes contact with the liquid jet through circularly arranged burners. And as far as I know at the moment, it is not possible with Star CCM to carry out a two-phase simulation (liquid and gas --> VOF) and thereby model a combustion reaction in the gas phase in parallel. If that is possible, it might work. Alternatively, simplifications would be a possibility to avoid the combustion reactions.

Also, I am always open to other approaches.

BR
Tobias

There is also the Euler-Euler framework, which you can use. The gas can be just what you get from the combustion, so there is no need to model the combustion directly unless the contact with the liquid influences the combustion.

www.beilke-cfd.de
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