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

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 calculation is 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 parameters to 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@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@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@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@hotmail.com>
To: TRNSYS <trnsys-users@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@lte.ireq.ca>
To: <trnsys-users@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@jkr.gov.my>
To: "trnsys-users@cae.wisc.edu" <trnsys-users@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@solamen.fr>
To: <trnsys-users@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

antoine.gautier@solamen.fr

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David BRADLEY
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