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Author Topic: smoke exhaust  (Read 4385 times)

Minli

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smoke exhaust
« on: April 02, 2014, 03:50:28 am »

        Hi,
        could you help me to solve the problem:
        I established the vent of exhaust in order to lower the teperature and the hight of smoke layer. However, the hight of smoke layer cannot be lowered. I don't know how to solve the problem.
        I hope you could give me a hand, thanks!
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Charlie Thornton

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Re: smoke exhaust
« Reply #1 on: April 02, 2014, 09:12:09 am »

Can you post your model?
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Nitzan Hirsh

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Re: smoke exhaust
« Reply #2 on: April 08, 2014, 03:11:34 am »

I actually have a similar problem.
i've posted this simple example model.
as seen, the smoke layer height is not controlled regardless of HRR and/or exhaust velocity values.
Instead of removing smoke, the exhaust is decreasing the overall room pressure while smoke is still filling the room.
Thanks
Nitzan.
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Charlie Thornton

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Re: smoke exhaust
« Reply #3 on: April 08, 2014, 09:49:44 am »

example_exhaust1.psm doesn't have any source of make up air (i.e. it's trying to create a vacuum). If you add an OPEN vent it works like you would expect.
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Nitzan Hirsh

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Re: smoke exhaust
« Reply #4 on: April 09, 2014, 03:41:50 am »

Thank you for your response.
I've sent this example on purpuse, since my project is a room vith virtually no openings.
Would you recommend using leakage for that matter, or is is it needed to create a opening vent regardless?
Nitzan.
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Charlie Thornton

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Re: smoke exhaust
« Reply #5 on: April 09, 2014, 08:13:36 am »

I don't think an open vent is strictly necessary. Leakage sounds like the right answer if you want more control over the air coming in than the mesh resolution will give you. Though, honestly, I don't know much about the leakage approach.
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Nitzan Hirsh

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Re: smoke exhaust
« Reply #6 on: April 10, 2014, 04:39:38 am »

Same here.. I've been experimenting with leakage surfaces between zones but hav'nt seen meaningful results.
I'll let you guys know if I get any interesting findings.
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christofer.wickmark

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Re: smoke exhaust
« Reply #7 on: April 13, 2014, 07:57:25 pm »

A smoke extraction system always require make up air, usually quite big openings. Leakage only will not solve it for you, in practice anyway.
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