CFD‐Based and Control‐Oriented Modeling of a Counterflow Heat Exchanger With Utilization of Parameter Identification

ABSTRACT Counterflow heat exchangers (CHXs) thermally couple consumers and producers to a district heating network (DHN). Fluctuating loads and control actions naturally lead to unsteady operation conditions of the network and its components, posing a challenge for DHN models and CHX parameterizations based on Nusselt correlations that assume steady‐state conditions. However, transient processes are complicated. In any CHX, conjugate heat transfer (CHT) needs to be captured if accurate predictions are desired, since solid regions with finite heat capacity and thermal conductivity modify the responsiveness of the system. Here, an idealized, minimalistic CHX configuration is proposed that is topologically compatible with lumped, control‐oriented model formulations. The main objective of this paper is to exemplify how computational fluid dynamics (CFD) can be utilized for transient CHX simulations, enabling virtual control model development with the aid of dynamic parameter identification. It is demonstrated that the approach is capable of qualitatively capturing the temporal response using three different reduced‐order models for two different mass flow rate variations.