[TRNSYS-users] unit flow TRNSYS/CONTAM

David BRADLEY d.bradley at tess-inc.com
Mon Jan 16 05:54:26 PST 2012


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