[TRNSYS-users] Cooling load calculation

David BRADLEY d.bradley at tess-inc.com
Tue Feb 14 10:31:30 PST 2012


Mayank,
  It is very hard to get matching results between two people using the 
same software package, let alone between two different packages; there 
are so many assumptions in modeling. Still, what you report is a quite 
significant difference in sensitivity. I think the first place to look 
is that in your *.bui, you have left the default thermal capacitance of 
the zone as

VOLUME= 3027.33 m3
CAPACITANCE = 3632.79 kJ/K

this accounts only for the thermal capacitance of the air in the zone. 
It neglects the thermal capacitance of the furnishings. A more typical 
value would be 18200 kJ/h (approximately 5 times the default value).

Kind regards,
  David

On 2/14/2012 01:11, Mayank wrote:
>
> Hello Everyone,
>
> I have made a simple cooling load calculation model in TRNSYS v16 and 
> similar setup in E-quest. There is vast variation in cooling load when 
> I put into outdoor air in the room.
>
> In TRNSYS I used 2800 sqft area building having 150 person occupancy 
> and according to ASHRAE 62 (ventilation rate procedure) I calculated 
> 1150 CFM outdoor air as fresh air. When I taking no outdoor air the 
> cooling load is about 10 ton but when I put outdoor air through 
> ventilation (2.46 ACH) the cooling load increases and reached at 42 ton.
>
> And in E-quest it increase only 1 ton.
>
>  Can anyone help me to find out the reason?
>
> I attached bui. File and tpf file.
>
> Regards
>
> Mayank
>
>
>
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users at cae.wisc.edu
> https://mailman.cae.wisc.edu/listinfo/trnsys-users

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