Extension of Simulation Software for Thermodynamic and Other Systems Including Energy-Based Modeling

摘要

The author's Simulation Package for Thermodynamic Systems, which is freely downloadable from the internet, was specially designed to accommodate convection bond graphs, although it also handles conventional and hybrid bond graphs. Several new backward-compatible features have been added to this simulation package to enhance the flexibility of its non-thermodynamic aspects, such as its treatment of electromechanical components. First, multiport compliances, particularly nonlinear ones, are treated when the user merely inputs expressions for their potential energy, using the symbolic math toolbox of MATLAB®, making otherwise more extensive and awkward pre-analysis unnecessary. Second, the user is prompted how to input nonlinearities and time-dependencies of the non-thermodynamic components of a model. Third, activated bonds are accommodated. Finally, the former need to avoid certain zero initial conditions in certain cases is eliminated. The result is a general-purpose simulation package that has some advantages over alternatives even when no thermodynamics is involved, although it retains its special role as the most practical way to simulate systems with flowing fluids that undergo temperature and volume changes.