[TRNSYS-users] Error in solar radiation distribution (sumsitot) and type 56

Tue Jun 21 03:17:06 PDT 2011

Dear Mehdi,

thanks for resending your simplified files!

The error is due to very low radiation data on the north façade of your
model from Type 109 of 0.02 KJ/hr m².

Type 56 does a radiation distribution for this very low value which
yields to a total distribution error of radiation entering all windows
of 3.63 KJ/hr for your 3 floor window.

The 2floor model runs fine because there are less windows leading to an
error smaller than 3.6 kJ/hr.

As a quick fix I suggest to set radiation input to Type 56 lower than 1
KJ/hr m² to 0 by the following

IT_N_180_90 = [109,36]*GT([109,36],1)

IB_N_180_90 = [109,37]*GT([109,36],1)

In addition, I put it on my list for Type56 improvements. 

Best regards,

Marion

Dipl.-Ing. Marion Hiller 
TRANSSOLAR: KlimaEngineering - Technologien für energieeffizientes Bauen
und Nutzerkomfort in Gebäude 
Munich - New York - Stuttgart + 49.711.67976.0 

Transsolar Energietechnik GmbH, Curiestrasse 2, 70563 Stuttgart 
Amtsgericht Stuttgart - HRB 23347, Steuernummer 99073/00911, USt-IdNr.:
DE152272639

Geschäftsführer: Dipl.Ing. Matthias Schuler, Dipl.Ing. Thomas Auer,
Dipl.Phys. Stefan Holst, Prof. Dipl.-Ing. Bleicher 

  _____  

Von: Mehdi Shahrestani [mailto:mahdishahrestani at yahoo.com] 
Gesendet: Montag, 20. Juni 2011 00:27
An: trnsys-users at cae.wisc.edu
Betreff: [TRNSYS-users] Error in solar radiation distribution (sumsitot)
and type 56

Dear TRNSYS team and users

It is around 10 days that I have got stuck in simulation of a building.
After many things that I have already checked, it seems that there is a
bug in Trnsys. 

Here, I am going to raise the issue in detail hoping to get some
response from users and Trnsys bodies. 

Project: 

Modelling of a building with 3 floors without considering system (just
using type 56)

Each floor has 20 zones and the plans of all 3 floors are the same.

Followed process: 

In the first round the building was drawn in Trnsys3d-SketchUp and
imported into the Trnsys. After importing the *.idf file, a *.tpf file
was automatically generated and was working very well. The problem came
up when I needed to reduce simulation time step from 1 hr to 0.2 hr.
(for controller settings in the next steps of my project)

Any way, a simple type 56 for a building with 3 floors, each floor 20
zone was not working with 0.2hr simulation time step.

 The error is:

“Internal error in solar radiation distribution (sumsitot) of    56.388
% at time    56.40wave length band no.3 1:total solar, 2:visual solar,
3:non visual solar”

I was checking every thing but nothing was wrong. Finally, I sent an
Email for users and asked for help. Christian from TRANSSOLAR and Matt
from TESS kindly replied. Matt suggested me to follow the Christian
advice and Christian wrote:

“One reason for this can be that in your 3DModel you have infinitesimal
small surfaces. Please check if this is the case and if so you'll have
to redraw the geometry“

Then, I checked every little part of the 3D model in Sketchup and also
imported model in studio but there was not such evidence. 

Even though I was quite sure that there is no such a little surface I
redraw the entire model several times (at least 10 times) precisely but
the result was the same and after importing the *.idf file into studio
exactly at 56.4 hr the error comes up every time. 

In the next try I decided to draw and import building floor by floor.
After drawing the first floor, it was imported to the studio. Generated
*.tpf file including Type 56 ran with 0.2 hr simulation time step. The
result was perfect, and I decided to check the building with 2 floors.
To make the drawing I used the drawing of the first floor (previously
drawn) and copy it on the top of the first floor as second floor and
then import the related *.idf file into studio. Type 56 of the building
with two floors was working in 0.2 hr time step perfectly without error.
Then, I repeat the process and copy the drawing of the second floor and
paste it as third floor in Sketchup. After importing the *.idf  of the
building with 3 floors, type 56 was only able to run in simulation time
step 1.0 hr. when I was reducing time step to 0.5 or 0.2 the previous
error came up. 

All in all, this approach proved that there Christian’s expectation was
not correct because if it was correct I could not run the related type
56 for the first floor and second floor without error as well.( third
floor was copy and paste of second floor) 

Even though it was quite clear that there is no any small surface
(Christian expectation) I was thinking maybe there is some problem about
connection between Sketchup and studio. Therefore, I decided to insert
entire building manually in type 56. The result of manual filling type
56 was 100% similar to the importing building from Sketchup. That means,
first floor and second floor was running perfectly in different
simulation time step (0.2 hr , 0.5 hr and 1 hr) but just when I added
the third floor, type 56 came into the same error (mentioned above) at
the same time (56.4 hr). 

By following these two approaches I have got sure that the error is not
because of small and unattended surface (Christian expectation) and also
is not because of importing *idf file from Sketchup. 

This error has also detected by other users Xavier (2004) which Michaël
Kummert was replied and accepted the bug in version 15.

My expectation: 

1-     There are limits on number of zone for each type 56.

2-     Weather component (type 109) is not able to deal with some time
steps.

3-     There is a bug in type 56 to run model with time steps less than
1.0 hr.

4-     There is a bug for solar radiation distribution within type 56.

For further detail following files are attached: 

1-     Folder 1 including related files of building with two floors
developed in Sketchup and imported into Trnsys which works fine in
different time steps (*.idf, *.tpf, *.dck and *.b17 files)

2-      Folder 2 including related files of building with three floors
developed in Sketchup and imported into Trnsys which is not working in
time steps less than 1.0 hr  (*.idf, *.tpf, *.dck and *.b17 files)

Hereby, I was wondering if anybody could help me. I am not a freelance
researcher; I am a PhD student with dispread need on doing simulation. I
hope you consider user situation with your kind responses. 

Sorry about the long story and thanks for your time

Regards

Mehdi Shahrestani

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