[TRNSYS-users] FW: TYPE 56, Active layer minflow error

[David BRADLEY]

Patrick,

> Another question: the exterior walls  have a specified R value, does 
> it matter if i model the exterior walls with multiple layer with 
> combined is that R value or can i just implement 1 layer with the same 
> specified R value?
>
> As the walls a modeled with the response theory it does not really 
> matter what u stick  in between the frontside and backside aslong as 
> the R is the same correct?
>
it matters a lot. The R-value of a wall is only one measure of its 
performance. The thermal mass of the wall is of great importance too. 
You can get the same R-value with a small amount of insulation or with a 
colossal amount of concrete; the two walls will behave very differently. 
You're going to need to make some kind of educated guess about the 
construction of the wall. If you want to completely neglect the thermal 
capacitance of the wall, you can specify your exterior walls as being 
made up of a single, massless layer with the R-value that has been reported.

Also be careful in that R-values are sometimes specified with an assumed 
convection/radiation term on the inside and outside surfaces. Therefore 
the R-value of the actual wall materials will be different from the 
R-value of the entire wall.

Best,
  david



> ------------------------------------------------------------------------
>
> *From:*David BRADLEY [d.bradley at tess-inc.com]
> *Sent:* Thursday, October 18, 2012 4:05 PM
> *To:* Patrick Fabriek
> *Cc:* trnsys-users at cae.wisc.edu <mailto:trnsys-users at cae.wisc.edu>
> *Subject:* Re: [TRNSYS-users] TYPE 56, Active layer minflow error
>
> Patrick,
>   This is a known bug and one that we are working on solving. The 
> problem appears to come from a dynamic calculation of the transition 
> between laminar and turbulent flow which (to my understanding) 
> includes a correction for the actual water temperature when performed 
> during a simulation in Type56 but for an assumed water temperature 
> when performed in TRNBuild. I have found that if you increase the mass 
> flow rate by a bit then you get away from the problem. It sounds, 
> however, as though this hasn't worked in your case. If the project is 
> not too complicated, please send it and we can have a closer look 
> internally.
> Kind regards,
>  David
>
> On 10/18/2012 05:57, Patrick Fabriek wrote:
>
>     Dear Trnsys users,
>
>     I have been using Trnsys for a months now and trying to model a
>     simple single floor Zero energy house recently build in Rotterdam.
>
>     Im now at the point where i am defining the floor heating with
>     active layer in TRNBuild but  i get this error : Specific fluid
>     mass flow of active layer in surface 1 below minimum value of
>     12,98 kg/m2h.
>
>     The minimum allowed inlet specific mass flowrate is valued at
>     16.68 kg/ h m2 so this error is very strange. I put the desired
>     specific flow rate at 17.
>
>     I have been increasing the massflow or lowering it still give the
>     error.
>
>     Does trnsys studio recalculate specific value somewhere else?
>     anyone has a another solution for implementing floor heating.
>
>     Regards,
>
>     Patrick F
>
>
>
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>
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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  <mailto:d.bradley at tess-inc.com>
>   
> http://www.tess-inc.com
> http://www.trnsys.com

-- 
***************************
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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