[TRNSYS-users] problem of convergence

[David Bradley]

Yujun,
 I would not recommend loosening the tolerances in order to get the 
simulation to run. You can get information on what those tolerances are 
in the TRNEdit manual. The two things that I would start with on your 
simulation are to first increase the thermal capacitance of your zones 
to something like five times the default value. Recall that the default 
value accounts only for the thermal capacitance of the air in the zones 
and not for any furnishings. Second, I think you will need to run with a 
time step less than one hour. Since TRNSYS can only make control 
decisions once per time step, an hour is a very long time for control 
decisions. The results of your equation "infil sur EscS et DP" change 
the infiltration rate into your building, which in turn change the 
building temperatures, which in turn change the infiltration rate. That 
infiltration rate, applied to the building for an entire time step (an 
hour) prevents convergence of the building temperatures. I would 
recommend a time step on the order of 5 minutes.
Kind regards,
 David


Yujun TAO wrote:
> Hello,
> I have a problem of convergence when i simulated a complex building 
> with double skin ventilated. I found when the window "adjacent" has a 
> big surface like 60m² in zone "DPSE", the simulation took many times 
> and is difficult to converge. When the surface reduced like just has 
> 10m², the simulation goes fast and has no problem of convergence. But 
> the window should have 78m² in the reality.
> So how could I resolve this problem?
> Sorry the files bui and tpf couldn't be attached with mail, blocked by 
> the firewall of yahoo.
>
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Thermal Energy System Specialists (TESS), LLC 
David BRADLEY                      22 N. Carroll Street - Suite 370 
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