[TRNSYS-users] small mass flow in TABS

[David BRADLEY]

Karol,

  In the screencap that you sent it is the value currently set to 10 
that you need to adjust. The model is saying that as long as the flow 
rate to the floor is greater than 9.09 kg/h.m2 (1229.52 kg/h) then you 
don't need auto segmentation. If you want a lower flow rate than that 
(for example 8 kg/h.m2) then change the value currently set to 10 to 8 
and you should then have the ability to segment the floor. The number of 
loops has a minor impact on the allowable flow rate.

kind regards,

  David



On 06/04/2018 13:58, Karol BANDURSKI wrote:
>
> David,
>
> Both this errors have appeared when I decrease mass flow rate two 
> times and increase number of loops 10 times…
>
> I don’t know way, but I don’t have option “autosegmentation” (print 
> screen enclosed)…
>
> It seems to me that increase of loops number has not change minimum 
> allowed mass flow rate.
>
> Kind regards,
>
> Karol
>
> *From:*David BRADLEY [mailto:d.bradley at tess-inc.com]
> *Sent:* Monday, June 4, 2018 7:06 PM
> *To:* TRNSYS users mailing list at OneBuilding.org 
> <trnsys-users at lists.onebuilding.org>; trnsys-users at cae.wisc.edu
> *Cc:* Karol Bandurski <karol.bandurski at put.poznan.pl>
> *Subject:* Re: [TRNSYS-users] small mass flow in TABS
>
> Karol,
>
>   I do not think that the problem with the matrix inversion and the 
> low flow rate in the active layer are necessarily related. I'm not 
> sure what to suggest about the matrix inversion. The active layer 
> model has a minimum allowable flow rate that is based on pipe spacing, 
> the thickness of the layer(s) in which the pipes are embedded and the 
> area of the floor. If you want to give a lower flow rate then you need 
> to segment the floor, which means treating the floor like it was a few 
> floors in series. Enter the desired minimum mass flow rate in the 
> active layer definition screen. If it is below the minimum "allowed" 
> mass flow rate then you'll have the option to segment the floor.
>
> kind regards,
>
>  David
>
> On 06/04/2018 01:58, Karol Bandurski via TRNSYS-users wrote:
>
>     Dear Experts
>
>     I have problem with simulation TABS with specific mass flow rate
>     about 5.4 kg/hm2.
>
>     There are two errors:
>
>     1)Specific fluid mass flow of active layer in surface  894 below
>     minimum value of 8.90 kg/m2h Please, increase the minimum mass
>     flow rate or use the autosegmentation feature of TRNBuild for
>     subdividing the surface.
>
>     2)Subroutine INVERT was called from subroutine INVPAR with a
>     singular matrix!
>
>     I have increase number of loops 10 times but nothing change…
>
>     It is possible to do simulation with so low mass flow rate?
>
>     Kind regards,
>     Karol
>
>     --------------------------------------------------------------------
>
>     Karol BANDURSKI M. Sc.
>
>     Faculty of Civil and Environemntal Engeneering
>
>     Division of Heating, Air Conditioning and Air Protection
>
>     Poznan University of Technology
>
>     https://www.researchgate.net/profile/Karol_Bandurski
>
>     www.put.poznan.pl/~karol.bandurski
>     <http://www.put.poznan.pl/%7Ekarol.bandurski>
>
>
>
>
>     _______________________________________________
>
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>
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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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