[TRNSYS-users] Lumped capacitance model

[David Bradley]

Sophie,
   8 hours seems long to me as well. Would you mind sending me your input 
file so that I can see what the zone parameters (loss, size, etc.) are?
Cheers,
  David


At 13:32 4/2/2007, Sophie Masson wrote:
>Hi Folks,
>
>I am modeling a zone both in TRNSYS and in Matlab with ventilation but
>no infiltration and no occupancy or lighting gains.
>(conditions:
>- initial room temperature = 10C
>- outside air temperature = 10C
>- ventilation air temperature = 26C
>- ventilation air change = 3 ACH/hr (432 kg/hr) )
>
>In TRNSYS, I have 2 different zone models (Type 56 and Type 88, lumped
>capacitance). The model in Matlab is a lumped capacitance model (with a
>1 second - simulation time step).
>
>I am using the same inputs (building dimensions, capacitance, loss
>coefficient...) for the 3 models. The room air temperature reaches the
>setpoint (20C) in 20 min with the Matlab model and ... 8hr with the
>TRNSYS model (whatever time step or wall base I choose).
>Why such a difference? Is it linked to the way TRNSYS calculates the
>results (hourly based and not calculate the energy accumulation each
>second)?
>8hr seems to be not reasonable, but I can not figure out where the
>problem comes from.
>
>Thanks for your help,
>
>Sophie
>
>--
>Sophie V. Masson
>Research Engineer
>Center for Building Performance and Diagnostics
>Carnegie Mellon University
>5000 Forbes Avenue
>Pittsburgh, PA 15213
>Phone: 412 268 3939
>Fax: 412 268 6129
>Email: smasson at andrew.cmu.edu
>
>
>_______________________________________________
>TRNSYS-users mailing list
>TRNSYS-users at engr.wisc.edu
>https://www.cae.wisc.edu/mailman/listinfo/trnsys-users

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