In Simulation CFD 2013 heat exchangers may be controlled by a specified supply temperature, a temperature difference, or a heat removal rate. However, many CRACs, CRAHs, and air conditioners supply air at a given temperature up until the point at which their capacity is exceeded. Beyond that temperature, the supply temperature will drift upward. Modeling this behavior would require a combination of some of the control modes currently available.
We understand there is some interest in this capability for certain users but are looking to see how wide the need is. If you see value in expanding the control options for heat exchanger materials to account for this behavior, let us know.