Re: [TRNSYS-users] air contact

Karol,
What I have often done is to define a coupling air flow between the two zones, then run the simulation once with very little coupling flow and then once with a high airflow. The values of "low" and "high" are somewhat arbitrary; the idea is to make a reasonable guess as to how much air transfer there is. If there is no real difference in the simulation outputs that I care about (such as comfort or total building energy consumption) then I am confident that I don't have to spend much time thinking about what a good value would be (the model isn't sensitive to the value). If I find that there is a high degree of sensitivity then I can focus some more effort there.

At the other end of the spectrum, you can of course implement COMIS, CONTAM, or TRNFlow in the building so as to get an estimate of what the transfer might be.
Kind regards,
David

On 2/14/2014 12:26, Karol Bandurski wrote:

Dear Jochen,

Thank you for your advice, but now I am looking for the values for such exchange, and the basis for this airflow assumption.

What is your practice with this issue?

Regards,
Karol

From: hotline [mailto:hotline@Transsolar.com]
Sent: Friday, February 14, 2014 4:48 PM
To: 'TRNSYS users mailing list at the Solar Energy Lab, UW-Madison'
Subject: Re: [TRNSYS-users] air contact

Dear Karol,

You can merge both zones to one zone and two airnodes. Please have a look into the manual 5.4.1 for the difference between airnode and zone.

1.       if you draw the building in SketchUp, you need to define the wall as a virtual surface, to merge them in TRNBuild ,use the 180° arrow on the upper left site of the zone window

2.       If you define the wall manually in TRNBuild ,you can add directly another airnode to the zone.

After merging you have two airnodes in the zone and you might need to define an air exchange see 5.2.4.10.

Best

__________________________________________________________________________________________________

Jochen Lam

TRNSYS Software Team

Transsolar Energietechnik GmbH

Curiestraße 2

70563 Stuttgart

Fax:        +49 711 67976-11
Email:    jlam@transsolar.com

Web:      www.trnsys.de

Von: trnsys-users-bounces@cae.wisc.edu [mailto:trnsys-users-bounces@cae.wisc.edu] Im Auftrag von Karol Bandurski
Gesendet: Freitag, 14. Februar 2014 15:24
An: trnsys-users@cae.wisc.edu
Betreff: [TRNSYS-users] air contact

Dear All,

I wondering how are you model air contact:

there is two zones (e.g. two rooms) and they are connected by air (e.g. doorway), there are no mechanical ventilation or intensive, one direction, air flow.

I think to assume some massless construction between this zones, but what resistance will be appropriate? Or maybe some both direction air flow, but how can I assume the value of the flow?

Do you have some idea?

Kind regards,

Karol

------------------------------------------------

Karol Bandurski MSc.

Institute of Environmental Engineering

Poznan University of Technology

www.put.poznan.pl/~karol.bandurski

www.ee.put.poznan.pl
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