RE: [EnergyPlus_Support] Re: Can Airflow Network simulate stack effect?

[Lixing Gu <gu@xxxxxxxxxxxx>]

Wonjun:

I don't know any limitations using the AirflowNetwork model to simulate DSF
cavity airflows, because I never tested it. The model provides a network
approach. I think that as long as you input correct inputs, you may expect
better results.

Thanks for letting me know you and others have simulated DSF performance and
obtained satisfied results. We have an enhancement item to model DSF using
the AirflowNetwork model, but we don't have timetable yet. Is it possible
for you to share the experimental data with us to validate the mode in the
future?

Thanks.

Lixing


-----Original Message-----
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Wonjun
Sent: Tuesday, October 19, 2010 1:31 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: Can Airflow Network simulate stack effect?

Thanks for your valuable answer, Lixing. 

Even though stack effect has been validated with ASHRAE analytic solution,
what is the limitation in case of simulate DSF cavity flow?
Is it just not accurate in that AFN can't simulate the temperature
stratificaiton, or is there other reason exist? 

When I made a DSF building with the AFN algorithm, the result seemed to
pretty well matched from air physical view(Comparing airflow rate and
velocity of lower part opening and upper part opening). 

I have read the simulate DSFs with AFN algorithm published in ASHRAE
Transactions.

For example 
http://www.bwk.tue.nl/bps/hensen/publications/02_ashrae_dskin.pdf

I wanna know the exact limitation of the AFN algorithm when I use it to
simulate DSF cavity flow. 
 
Many more thanks in advance. 
 

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Lixing Gu <gu@...> wrote:
>
> The stack effect comparison was performed to compare analytical results
> provided by ASHRAE research project 1052. Here is a link to get a pdf
file:
>
http://apps1.eere.energy.gov/buildings/energyplus/pdfs/energyplus_ashrae_105
> 2rp_envelope.pdf. Section 2.12 "Test Infiltration-2, Stack Effect"
provides
> detailed description.
> 
> The algorithm is not designed to simulate the DSF cavity airflows. 
> 
> Thanks.
> 
> Lixing
> 
> -----Original Message-----
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Wonjun
> Sent: Monday, October 18, 2010 9:43 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Can Airflow Network simulate stack effect?
> 
> I have already read I/O reference and engineering reference related to
AFN. 
> In engineering reference which states AFN algorithm, it states that this
> algorithm considers the pressure differece by density and height. 
> But I don't know whether this algorithm can simulate the ventilation by
> stack effect. (For example double skin facades' cavity flow)
> I know this algorithm assumes that the air is perfectly mixed and has
> uniform property. 
> Then, how AFN algorithm can describe the temperature stratification? 
> Is there a validation document related to AFN's stack effect limitation?
> (I.e., when you try to simulate a zone higher than specific height, the
> results will not accrate. This kind of document) 
> 
> Please give me a help. 
> Many thanks in advance.
>  
> 
>  
>  
> 
> 
> 
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