# Heating vertical liquid stream with parallel gas

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 May 5, 2023, 08:57 Heating vertical liquid stream with parallel gas #1 New Member   Join Date: Mar 2020 Location: germany Posts: 9 Rep Power: 6 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

 May 8, 2023, 03:50 #2 Senior Member   Joern Beilke Join Date: Mar 2009 Location: Dresden Posts: 503 Rep Power: 20 Is the gas separated from the liquid by a wall or are they mixed within the "pipe"?

May 8, 2023, 07:51
#3
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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

Quote:
 Originally Posted by JBeilke Is the gas separated from the liquid by a wall or are they mixed within the "pipe"?

 May 8, 2023, 09:30 #4 Senior Member   Joern Beilke Join Date: Mar 2009 Location: Dresden Posts: 503 Rep Power: 20 Why don't you want to use a multiphase approach? That's what I would try at first.

 May 8, 2023, 18:42 #5 Senior Member   Chaotic Water Join Date: Jul 2012 Location: Elgrin Fau Posts: 436 Rep Power: 17 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?

May 15, 2023, 08:42
#6
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Quote:
 Originally Posted by JBeilke 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

May 15, 2023, 08:46
#7
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Quote:
 Originally Posted by cwl 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

May 15, 2023, 09:04
#8
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Joern Beilke
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Quote:
 Originally Posted by tohell92 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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