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Re:



Here is a reply from Torsten Welfonder, who is having some email problems...

Michaël Kummert

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Dear Sounghun Yun,

first with TYPE 9 you have to be careful if you don't want to interpolate you have to use
-1 for the first data, for the second -2 and so on if you use always -1 this will only effect the first
data you read in.


For the timestep if you have a large influence of the ventilation it is always better to simulate with smaller timesteps like
e.g. 0.01 h due to this will lead to a smaller amount of energy change in one timestep and this is important for convergence.



For the comis problem. This problem is solved with TRNFLOW.
you find more about TRNFLOW at http://www.trnsys.de/ts/english/softeng/floeng/floeng.htm
TRNFLOW is COMIS integrated in TYPE56. the Thermal model and the airflow model are now linked internally. A new internal solver was integrated in TYPE56 which makes the simulations much more stable.


--- The rest of the email is attached as a Word document ---
--- (the only way to get a reasonable file size)---


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on 2004-05-24 23:21, Sounghun Yun wrote:

Hi, every trnsys users.

I found some trouble from the result of Comis/Trnsys coupling
calculation when there were severe indoor-outdoor temperature
differences.  That is, when the indoor-outdoor temperature
difference changed for a time step (changing about 3 or 5 degree
  C for 1 hr), the amount of infiltration of building falling
down unreasonably.  Generally speaking, if there was no wind
around a building, the amount of infiltration of a building
should have to be the smallest value when the indoor-outdoor
temperature differences become zero.  And, I confirmed this like
  result from the calculation of Comis stand-alone (single zonal
mode and multi zonal model, too).
Indeed, I handled the weather data to be no wind speed and the
outdoor temperature should be changed step by step (for eg., 15
degree C for 12 hours and 20 degree C for the next 12 hours, etc.
   And the indoor temperature is set to 20 degree C) for the
purpose of finding some clue.  And the unreasonable value was
found at the time when the temperature difference changed.  I
have one more question in here ; why the output data is
interpolated even though Type9 was set not to interpolate any
input value(I entered "-1" for the setting of interpolation)?
The problem was occurred at the time step of interpolation.
When I set the simulation time step of control cards to be
smaller(for eg. 10 minute), the results showing better than
large time step(1hr).  Is there any relationship between the
time step and Trnsys-Comis coupling?

Any one who has good idea about these problems, teach me please..

Best regards

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below : an example

     Tin(C) Tout(C) infiltraion(m3/h)
3:00   20     10        40
4:00   20     10        40
5:00   20    12.5        6    <-- I entered 10 degree C for 5:00
6:00   20     15        30
7:00   20     15        30

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--
_________________________________________________________

Michaël Kummert

Solar Energy Laboratory - University of Wisconsin-Madison
1303 Engr Res Bldg, 1500 Engineering Drive
Madison, WI 53706

Tel: +1 (608) 263-1589
Fax: +1 (608) 262-8464
E-mail: kummert@xxxxxxxxxxxxx

SEL Web Site: http://sel.me.wisc.edu
TRNSYS Web Site: http://sel.me.wisc.edu/trnsys

Attachment: COMIS_TRNSYS_questions.doc
Description: MS-Word document