[TRNSYS-users] unit flow TRNSYS/CONTAM

[Karol Bandurski]

David,

 

It seems to me that I have made 'discovery':

 

Infiltration (Ambient -> zone) in Type 97 is given by airchanges per hour,
but exfiltration (zone ->Ambient) by kg/h!

Am I right? It is general rule? Or I had to do some settings which determine
that.?

 

I thought that exfiltration and infiltration has the same units  - it seems
that it is the reason why my air balance was wrong.

 

Regards,

Karol

 

 

From: David BRADLEY [mailto:d.bradley at tess-inc.com] 
Sent: Monday, January 16, 2012 2:54 PM
To: Karol Bandurski
Cc: trnsys-users at cae.wisc.edu
Subject: Re: unit flow TRNSYS/CONTAM

 

Karol,
 My apologies; I did not see your earlier email.

 Type97's outputs for flow rates into a zone from ambient are in airchanges
per hour. The units for the interzonal air flow rate outputs are kg/h. As a
side note, the CONTAM help states that interzonal air flow rate outputs are
in kg/s but in fact they are in kg/h.

 You are correct about the units of Type3 and Type56 although in Trnsys 17,
you are able to select whether you want to provide Type56 airflow inputs in
airchanges per hour or in kg/h.

 As I see it, you have two options for seeing the results in m3/h. You can
either convert outputs to m3/h using a constant assumed air density of 1.2
kg/m3 in an EQUATION block or you can use Type33 to compute a variable air
density. The first option is simpler and probably good enough; Type56
assumes that the air pressure is always 1 atmosphere.

  As for exfiltration and infiltration not matching, I would imagine that
they should match if you do not define a mechanical system and just let the
building "float." However, if you have a mechanical system that adds outdoor
air to the building and you do not also define an exhaust fan then all that
additional outdoor air must get out of the building by exfiltration. In the
US, a lot of buildings are pressurized a little bit to force exfiltration to
be higher than infiltration. The result that you are given by the simulation
also depends a bit upon whether you have defined an AHS in CONTAM.
Kind regards,
 David


On 1/16/2012 05:22, Karol Bandurski wrote: 

Dear Users

 

Because my problem is very important for me I will ask again to remind my
issues.

 

I use type 56 (TRANBuild), type 97 (CONTAM) and type 3c (fan) to simulate
ventilation.

 

A.      The problem is that each type have other outputs/inputs units:

 

-          It seems to me that outputs of type 97 are air change rate per
hour.

-          Flow rate in type 3c and 56 is given by kg/hr.

-          I would like to get results in m3/hr.

 

So my questions:

1)      Should I do some conversion of units between fan (type 3c) and
CONTAM (type 97) or between CONTAM and Type 56?

 

2)      How can I get air flow in m3/hr or kg/hr form type 97?

 

B.      The second issue is that I calculate year-round infiltration and
exfiltration for my model (natural ventilation) using type 97 and type 28b
(Simulation Summary) and it appear that exfiltration is much larger. How it
is possible???

It seems to me that exfiltration and infiltration air should be equal if
there is no other way for air.

 

Regards,

Karol  

 

 

------------------------------------------------

Karol Bandurski MSc.

 <http://www.ee.put.poznan.pl/> Institute of Environmental Engineering

Poznan University of Technology

 <http://www.ee.put.poznan.pl/> www.ee.put.poznan.pl

www.put.poznan.pl <http://www.put.poznan.pl/> 

 





-- 
***************************
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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