[TRNSYS-users] Fwd: Strange Opening Factor (OF) of Window

David BRADLEY d.bradley at tess-inc.com
Wed Oct 5 13:52:21 PDT 2011


Wang,
  I apologize but I don't know the answer to your questions. I am not 
familiar with TRNFlow/COMIS; I use the CONTAM/Type97 option for my work 
on combined thermal/airflow studies.
Kind regards,
  David


On 10/5/2011 14:51, 王洋 wrote:
>
>
> Dear Mr. Bradley
>
> Many thanks for your patient reply!
>
> 1) Firstly, I only defined one Thermal Airnode in one zone, two 
> External nodes, two Large opening. So I guess the reason is not the 
> first you said. But I found the definition of Large opening, 
> especially For Closed Opening: flow coefficient Cs per m crack is 
> 0.0001 kg/s/m at 1 Pa. Moreover, I found indeed the hot air escapes 
> from the zone about 2.42 kg/h after I set the OF as 0 (from 6 pm to 8 
> am). But when I set Cs as 0 kg/s/m at 1 Pa, moreover, I defined wind 
> pressure coefficients Cp as 0 for 2 external nodes, there is still a 
> WEIRD thing: the CO2% still decreases, however, the hot air escapes 
> from the zone about 0.65 kg/h (which is almost the same from 6 pm to 8 
> am) after I set the OF as 0. I guess COMIS maybe still has an default 
> although OF is 0 and Cs is 0 kg/s/m. But I indeed need CO2% as a 
> constant after OF is 0.
>
> 2) For your second reason, I checked the COMIS documentation. I found 
> Air Flow calculationis a steady state simulation, however, the 
> Pollutant Transport is calculated with a dynamic model. Whether CO2% 
> decreases due to this reason i.e. COMIS is trying to predict CO2%, 
> when OF is 0 (Air Flow calculation), however, CO2% is still calculated 
> by COMIS (after OF is 0 during this simulation step). But like 1), the 
> hot air escapes from the zone about 0.65 kg/h (which is almost the 
> same from 6 pm to 8 am) after I set the OF as 0. Hence, I think this 
> reason 2) is still not reasonable. Moreover, I found although TRNFlow 
> ‘s engine is COMIS, for some issues, the manuals of both of them COMIS 
> and TRNFlow are still not clear and relative completely. Could you 
> introduce other references or COMIS (EMPA) guys to give me an exact 
> answer for this WEIRD thing? Because it troubles me for a long time. I 
> need find the stable PID parametersto control OF which can keep CO2% 
> under or at the set-point 1000 ppm. Until now, I found the stable PID 
> parameters for one day, but due to CO2% decreases after OF is 0 from 6 
> pm. Hence, the stable PID parameters for one day don’t work for next 
> day from 8 am. Please see the ATTACHED. The stable PID parameters 
> maybe are too large for next day’s CO2%.
>
> 3) For your third reason, I only defined 2 Large opening not including 
> fans and ducts etc. by TRNFlow, maybe you think they two large opening 
> are a true Mechanical ventilation system?
>
> Many thanks in advance!
>
> Br.
>
> wang
>
>
>
> 2011/9/30 David BRADLEY <d.bradley at tess-inc.com 
> <mailto:d.bradley at tess-inc.com>>
>
>     Wang,
>       I will preface this by mentioning that I am not an expert in the
>     TRNFlow part of Type56.
>
>       It is a little hard to know what is going on without knowing
>     anything about the building. However, if you have multiple zones
>     in the building, I imagine that there would be some air mixing
>     going on between zones due to internal temperature and height
>     differences and the CO2 concentration would decrease in one zone
>     while increasing in another.
>
>       I would also recommend looking at the COMIS documentation (COMIS
>     is the engine that underlies TRNFlow) to see whether its
>     algorithms are trying to predict CO2 concentration at a particular
>     point in the space (like we do in Type56 for comfort calculations
>     at a particular point in a zone) or whether it is assuming a fully
>     mixed zone as far as the CO2 level is concerned. If COMIS is
>     calculating concentration at a point and the air continues to mix
>     after your opening factor has gone to zero then that might explain
>     the decrease.
>
>      Lastly, your mechanical ventilation system might have something
>     to do with the decrease; If you are actively supplying air to the
>     space after the opening factor is zero and if the mechanical
>     ventilation system has some outdoor air associated with it then
>     that also would explain the decrease in CO2 level.
>
>     Regards,
>      David
>
>
>
>     On 9/30/2011 08:47, 王洋 wrote:
>>     Dear all,
>>          I simulated CO2 concentration changes using TRNFlow. But
>>     there is a STRANGE phenomenon. There are 2 occupants from 8am to
>>     6 pm, CO2% is controlled by PID controller which controls Opening
>>     Factor (OF) of window at the set-point 1000 ppm. From 6 pm, there
>>     are no occupants, OF is 0, there is no infiltration in TRNBuild
>>     (Certainly, infiltration in TRNBuild indeed will inactivate when
>>     couping TRNFlow based on TRNFlow Manual). However, from 6 pm,
>>     CO2% begins to decrease. It's extremely strange!
>>        Which relative expert can expain that? Or give me some advices
>>     for that? I am puzzled for a long time.
>>        Many thanks in advance!
>>       br
>>      wang
>>
>>     2011/9/30 <trnsys-users-request at cae.wisc.edu
>>     <mailto:trnsys-users-request at cae.wisc.edu>>
>>
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>>         Today's Topics:
>>
>>           1. Using Excel as Load Profile (Pei Ru Chao)
>>           2. TRNSYS error 300 (torres.carlos-moises at lte.ireq.ca
>>         <mailto:torres.carlos-moises at lte.ireq.ca>)
>>           3. Direct expansion solar collector (Mohamad Azly Abd Aziz
>>         (Ir))
>>           4. simulation studio crash when updating project (Antoine
>>         Gautier)
>>
>>
>>         ---------- 已转发邮件 ----------
>>         From: Pei Ru Chao <simplica1 at hotmail.com
>>         <mailto:simplica1 at hotmail.com>>
>>         To: TRNSYS <trnsys-users at cae.wisc.edu
>>         <mailto:trnsys-users at cae.wisc.edu>>
>>         Date: Fri, 30 Sep 2011 16:31:53 +1000
>>         Subject: [TRNSYS-users] Using Excel as Load Profile
>>         Hi all,
>>
>>         As a newbie I am wondering how to use Excel for load profile
>>         input. Can anyone point me in the right direction as to how
>>         to use a Data Reader to do this? For example, can the Data
>>         Reader read 10920 rows of data? In 9a for example, Parameter
>>         2 asks how many values of input to read and the maximum is
>>         only 98?
>>
>>         Thanks
>>
>>         Pei
>>
>>
>>
>>
>>         ---------- 已转发邮件 ----------
>>         From: <torres.carlos-moises at lte.ireq.ca
>>         <mailto:torres.carlos-moises at lte.ireq.ca>>
>>         To: <trnsys-users at cae.wisc.edu
>>         <mailto:trnsys-users at cae.wisc.edu>>
>>         Date: Thu, 29 Sep 2011 15:50:36 -0400
>>         Subject: [TRNSYS-users] TRNSYS error 300
>>         Dear all,
>>         Whenever I ry to run a type 56 simulation in TRNSED I am
>>         given the following error even though the same program runned
>>         perfectly in TRNEdit
>>          ***** ERROR *****        TRNSYS ERROR # 300
>>          UNABLE TO START PROGRAM IN CALLPROGRAM UTILITY
>>          PLEASE CHECK PATH AND PROGRAM NAME, THIS MAY BE A PROBLEM IN
>>         TYPE 66
>>
>>         *** Fatal Error at time   :         0.000000
>>             Generated by Unit     : Not applicable or not available
>>             Generated by Type     : Not applicable or not available
>>             TRNSYS Message    300 : The TRNSYS Program attempted to
>>         evaluate an EQUATION that raised a negative number to a
>>         non-integer value. Please check the EQUATION formulation and
>>         re-run the simulation
>>             Reported information  : Not available
>>         the message is not very helpfull and I don't even use Type 66
>>         in my simulation and I checked all my equations and nothing
>>         obvious comes to view.
>>         Is there any known solution to this problem? If need be I can
>>         send you the files im using.
>>         Thank you
>>         Carlos Torres
>>         Stagiaire universitaire
>>         Laboratoire des technologies de l'énergie (LTE)
>>
>>
>>         ---------- 已转发邮件 ----------
>>         From: "Mohamad Azly Abd Aziz (Ir)" <AZLY at jkr.gov.my
>>         <mailto:AZLY at jkr.gov.my>>
>>         To: "trnsys-users at cae.wisc.edu
>>         <mailto:trnsys-users at cae.wisc.edu>"
>>         <trnsys-users at cae.wisc.edu <mailto:trnsys-users at cae.wisc.edu>>
>>         Date: Fri, 30 Sep 2011 04:36:25 -0700
>>         Subject: [TRNSYS-users] Direct expansion solar collector
>>
>>         Hi
>>
>>         I wonder whether someone has come-out with heat pump type
>>         with direct expansion solar collector/evaporator?.
>>
>>         Regards
>>
>>         Azly
>>
>>
>>
>>         ---------- 已转发邮件 ----------
>>         From: "Antoine Gautier" <antoine.gautier at solamen.fr
>>         <mailto:antoine.gautier at solamen.fr>>
>>         To: <trnsys-users at cae.wisc.edu
>>         <mailto:trnsys-users at cae.wisc.edu>>
>>         Date: Fri, 30 Sep 2011 13:48:10 +0200
>>         Subject: [TRNSYS-users] simulation studio crash when updating
>>         project
>>
>>         Dear all
>>
>>         I cannot update my project any more without crashing
>>         simulation studio (*.tpf and *.b17 in attachment).
>>
>>         Is there another way to update the input list for Type56 so
>>         that I can keep on working?
>>
>>         Thanks a lot for your help.
>>
>>         Best regards
>>
>>         --
>>
>>         Antoine Gautier
>>         Solamen
>>         +33 6 98 78 56 46 <tel:%2B33%206%2098%2078%2056%2046>
>>
>>         antoine.gautier at solamen.fr <http://lamen.fr/>
>>
>>
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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  <tel:%2B1.608.274.2577>
>     F:+1.608.278.1475  <tel:%2B1.608.278.1475>
>     d.bradley at tess-inc.com  <mailto:d.bradley at tess-inc.com>
>
>     http://www.tess-inc.com  <http://www.tess-inc.com/>
>     http://www.trnsys.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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