[esp-r] Re: Zero Stack Pressure

Thu Jun 10 16:31:57 BST 2010

Hi Achim,

Thank you.

Actually this is not a large atrium. This is only 4 meter*5.1 meters in the
plan. I have tried several types for splitting zones horizontally: first,
one main zone and four bypass zones in four sides, then one main zone and
two bypasses on the corners and finally one main zone and one bypass on the
corner with a door component. The results was nearly the same. Maybe if I
add a leakage to the lowest zone I see the effect.

Yes! You can see the temperature stack in the attached file.

Unfortunately, I have not the model now and I cannot test your suggestions
in the next few days. But I will do it soon and then I will inform you the
results.

Thanks again,

Mostapha

On Thu, Jun 10, 2010 at 10:53 AM, Achim.geissler <achim.geissler at intergga.ch
> wrote:

> Hi Mostapha
>
>
>
> in additio! n to the below, I think your approach with only one zone having
> external openings may be a general problem. The flow simulation can't really
> solve this, I think, because what you have is a possible flow path chain
> >in< the atrium (which is basically set up very good, I would think) which
> is singularily connected to the outside. Remember that one zone node can
> have only one temperature / pressure at one time step.
>
>
>
> Also, I would expect such a large atrium to have >some< leakage in the
> lower floor (entrance door etc.).
>
>
>
> Possible measures:
>
> a) Split the topmost zone into two (or three) that each have a connect to
> an exterior node
>
> b) also split the lowermost zone into two
>
> c) as written below, add some leakage to the lowermost zone
>
>
>
> Do the thermal results seem plausible? Do you have a "nice temperature
> stack" in the stacked zones?
>
>
>
> Best
>
> Achim
>
>
> --------- Original-Nachricht --------
> Von: "Achim Geissler" <achim.geissler at intergga.ch>
> An: "Mostapha Sadeghipour" <sadeghipour at gmail.com>
> Cc: "Aizaz Samuel" <aizaz.a.samuel at strath.ac.uk>, esp-r at lists.strath.ac.uk
> Betreff: [esp-r] Re: Zero Stack Pressure
> Datum: 09/06/10 23:13
>
> Hi Mostapha
>
> looking at your .a! fn, I think the problem is that all your connections to
> external nodes are in one zone (01).
>
> To get an afn up and running, a basic requirement is that for every zone
> you can go from an external node to a zone ... to >the< zone ... to a zone
> ... and so on and then to a (different) external node again. I think this
> does not hold for your afn. Add a connection type "tiny", e.g. a crack a
> factor 10 or 100 smaller than your _crk types and connect the lowermost
> zone(s) to an additional external node.
>
> Then something should happen and there should be pressure differences.
>
> Best
> Achim
>
>
>
>
> On Jun 9, 2010, at 2:47 PM, Mostapha Sadeghipour wrote:
>
> Hello Aizaz,
>
> I think the problem is not the node heights in my case, however I'm not
> sure. The .afn file is attached.
>
> Regard! s,
>
> Mostapha Sadeghipour
>
> On Wed, Jun 9, 2010 at 3:54 PM, Aizaz Samuel <aizaz.a.samuel at strath.ac.uk>wrote:
>
> Look up how node heights are defined in exemplars>network
> ventilation>alternative facade vent.....
>
> Theory can be found in Jan Hensen's thesis (section 4.3.2) available at
> http://www.esru.strath.ac.uk/publications.htm
> --
> Dr Aizaz A Samuel
> Department of Mechanical Engineering
> University of Strathclyde
> M324 James Weir Building
> 75 Montrose Street
> Glasgow, UK
> G1 1XJ
>
> T:+44 141 548 5765
> F:+44 141 552 5105
>
> On Wednesday 09 June 2010 11:28, Mostapha Sadeghipour wro! te:
>
> > Dear esp-r users,
> >
> > I'm modeling an atrium with a closed glass roof. The atrium has nearly
> 16m
> > height and it only connects to the outside through 3 cracks on the roof.
> I
> > divided the atrium into 5 vertical zones, and adjacent vertical bypass
> > zones. They are connected to each other through fictitious faces.
> >
> > Common orifice components connect zone nodes to each other vertically,
> and
> > door component connects zone nodes to bypass nodes horizontally. The
> > attached image shows the Air Flow Network in my model more clearly.
> >
> > I supposed that esp-r includes the stack effect whenever delta height
> > between the nodes and the component is not zero. So I expected to have a
> > stack pressure in the vertical connections. But when I check the results
> > the stack pressure in the connections are zero!
> >
> > I'm also curious! how esp-r consider the stack effects and the gravity?
> The
> > components dP are set manually and there is no "g" in the equations?
> Where
> > I can find the PSTACK equations that is used to calculate DP:
> > DP=PRES(IDPS)-PRES(IDNE)+PSTACK(ICNN).
> >
> > Thanks in advance.
> >
> > Mostapha Sadeghipour
>
>
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>
> achim.geissler at intergga.ch
>
>
>
>
>
>
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