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@tess-inc.com]
Sent: Monday, January 16, 2012 2:54 PM
To: Karol Bandurski
Cc: trnsys-users@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.
Institute of Environmental Engineering
Poznan University of Technology
www.ee.put.poznan.pl
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@tess-inc.com
http://www.tess-inc.com
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