[TRNSYS-users] small mass flow in TABS

Tue Jun 5 08:51:04 PDT 2018

David,

So you mean that o if I need both: detailed calculation and low mass flow, I
should divide active surface (ceiling/floor) on my own in SketchUp to allow
TRNSYS calculation.

Am I right?

Regards,

Karol 

From: David BRADLEY [mailto:d.bradley at tess-inc.com] 
Sent: Tuesday, June 5, 2018 4:58 PM
To: Karol Bandurski; 'TRNSYS users mailing list at OneBuilding.org'
Subject: Re: [TRNSYS-users] small mass flow in TABS

Karol 

  My apologies; I forgot to mention one very important thing! When you
segment a floor you're essentially adding more surfaces to the zone.
Therefore you cannot use the "3D Data" zone geometry mode nor the detailed
radiation modes. Open the zone/airnode window for the zone in question and
take the following steps:

1. click on the "Radiation Mode" button and switch everything to the
"standard" model. 

2. click on the "Geometry Modes" button then switch from "3D Data" to
"manual." 

3. go back to the radiant floor specification and you should be able to
activate the segmentation.

  Because of the need to shift away from detailed radiation models (which
may be quite important to your model) it might be worth looking at the
restrictions on the floor model with regards to how the pipe spacing and
layer thicknesses affect the minimum allowable flow rate. Perhaps there are
some modifications that you can make to the flow rate or the piping
configuration so that you can keep the detailed radiation models.

kind regards,

 David

On 06/05/2018 02:22, Karol Bandurski wrote:

David,

When I do what you advise then TRNBuild give information that it is
impossible (enclosed)

I will sent you also B17 file to allow that you could check it on yourself.

Regards,
Karol

From: David BRADLEY [mailto:d.bradley at tess-inc.com] 
Sent: Monday, June 4, 2018 11:12 PM
To: Karol BANDURSKI; 'TRNSYS users mailing list at OneBuilding.org'
Subject: Re: [TRNSYS-users] small mass flow in TABS

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
<mailto:trnsys-users at lists.onebuilding.org>
<trnsys-users at lists.onebuilding.org>; trnsys-users at cae.wisc.edu
Cc: Karol Bandurski  <mailto:karol.bandurski at put.poznan.pl>
<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

 <http://www.put.poznan.pl/%7Ekarol.bandurski>
www.put.poznan.pl/~karol.bandurski

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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

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

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