[TRNSYS-users] Time step for Pollution solver

Stefan de Kool s.dekool at chri.nl
Fri Dec 9 08:28:29 PST 2005



I have a problem modelling pollutant flow. I have a simple one zone-building
with inhabitants producing CO2. I use this concentration to control a fan.
The problem is that when I run the simulation, I get the following warning:


***** WARNING ***** UNIT 37 TYPE 56, TIME =   4.188E+00


 Pollutant transport solver : Small timestep

 needed (Tau < 10 sec), but is limited to 1 sec


appearing at every time step. But, when I decrease the time step below 56.25
sec (0.5^6*1hr), I get a range check error during the simulation (the first
couple of hours are plotted before the error). Does anyone have experience
with this? What causes the error? And is such a small time step always
needed when simulating pollutants or does it depend on e.g. the zone volume?


Thanks a lot,

Stefan de Kool


Cauberg-Huygen Raadgevende Ingenieurs

Lokatie Rotterdam


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