This information is part of the Modelica Standard Library maintained by the Modelica Association.
This example consists of a volume with a carbon dioxide concentration that corresponds to 1.519E-3 kg/kg, which is equal to 1000 PPM. There is a fresh air stream with a carbon dioxide concentration of about 300 PPM. The fresh air stream is such that the air exchange rate is about 5 air changes per hour. After 1 hour of ventilation, the volume's carbon dioxide concentration is close to the concentration of the fresh air.
The nominal value for the trace substance is set to
This scales the residual equations that are used by the solver to the right order