[TRNSYS-users] heat transfer problem through a wall

[David BRADLEY]

Salim,
   I do not think it is possible to set the initial wall surface 
temperature different from the zone air temperature. What I would 
recommend that you do is set up a month-long period at the start of your 
simulation during which your zone is subject to constant conditions 
(ambient temperature = 30C, no solar, no gains, etc.). This will get rid 
of all the initial transient behavior of the zone. You would then step 
change to your new fixed ambient temperature (and whatever other 
conditions you care about) and look at the wall energy transfer.
Regards,
  David


On 10/8/2010 03:37, salim mokraoui wrote:
>
> Dear Trnsys users,
>
> I'm trying to solve a heat transfer problem through a finite thickness 
> wall using Type 56 model (one uniform zone). I want to calculate the 
> energy flux from air node (fixed temperature) to inside surface  and 
> that from outside surface to outdoor (fixed temperature) as well as 
> inside and outside surface temperatures. The aim is to compare Trnsys 
> solution with another method. I could find significant results but I 
> have some problems with initialization.
>
> 1. I don't know how to give initial temperatures for the wall 
> different form that of the zone (Trnsys uses the same initial 
> temperature of walls than the zone )
>
> 2. If I set the initial temperature to 30 °C (for the zone and walls) 
> and 0 °C for ambient outdoor, the energy flux from outside surface to 
> outdoor starts from zero, which is not true.
>
> Have you any suggestion to solve these two problems ?
>
> Thank you
>
> With best regards.
>
> Salim MOKRAOUI
>
> Faculté des sciences de Nancy - LERMAB
>
> BP 239
>
> 54506 Vandoeuvre.
>
> Tél 03 83 68 48 47 - mél salim.mokraoui at lermab.uhp-nancy.fr
>
>
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> TRNSYS-users at cae.wisc.edu
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>    

-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

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