Robust Modeling of Volumes for Dynamic Simulations of Thermo-Fluid Stream Networks
Michael Meißner, Dirk Zimmer · IFAC-PapersOnLine · 2022
Modeling of complex thermo-fluid systems often leads to either many states or large non-linear systems of equations, which are both undesirable especially for real-time applications. Both of these issues can be solved by our algebraic stream-dominated approach to build hard real-time capable simulations. In this approach volume elements play a central role as boundaries and loop-breakers for fluid streams. In this paper, we first derive a lumped state standard volume model from first principle and then several specialized volumes for different applications. We regularize the models to perform robustly, even in degenerated operating conditions that might appear in dynamic simulations. While doing so, we show all approximations and assumptions used to arrive at the final models. Finally, we present some application examples showcasing the use of the different volumes for dynamic simulations. Alongside the models developed in this paper these examples are part of our open-source Modelica library and their implementation is therefore available.