[esp-r] Re: Zero Stack Pressure

[Jon Hand]

If someone has a good atrium model that they have confidence in and which
is well-documented then we could add it as an exemplar model for use
in training workshops and/or self-study.

Regards, Jon Hand
________________________________________
From: esp-r-bounces at lists.strath.ac.uk [esp-r-bounces at lists.strath.ac.uk] On Behalf Of Achim.geissler [achim.geissler at intergga.ch]
Sent: 10 June 2010 07:23
To: MostaphaSadeghipour
Cc: esp-r at lists.strath.ac.uk
Subject: [esp-r] Re: Zero Stack Pressure

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<mailto: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


<atr.afn>_______________________________________________
esp-r mailing list
esp-r at lists.strath.ac.uk<mailto:esp-r at lists.strath.ac.uk>
http://lists.strath.ac.uk/mailman/listinfo/esp-r

achim.geissler at intergga.ch<mailto:achim.geissler at intergga.ch>






________________________________

_______________________________________________
esp-r mailing list
esp-r at lists.strath.ac.uk<mailto:esp-r at lists.strath.ac.uk>
http://lists.strath.ac.uk/mailman/listinfo/esp-r