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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 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?
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.
When replying, please edit your Subject line
so it is more specific
than "Re: Contents of TRNSYS-users
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---------- 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?
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.