Thermodynamic Bond Graphs: A New Synthesis

Abstract

Thermodynamic Bond Graphs (TBG) are introduced, which are based on the thermodynamic state-space concept, but are extended to the Hamiltonian state-space of usual Bond Graphs by the sympletic gyrator (SGY). After the definition of physical domains, the SGY is shown to be an interdomain coupler, which can be eliminated by the definition of dual components, thus resulting in the usual Bond Graph concept. Not all domains of the TBG are coupled to another by an SGY however, and in usual Bond Graphs this is demonstrated by the fact that thermal and chemical (material) inductances do not exist. The main advantage of the TBG-concept is the possibility of systematic modeling of open (or convective) systems, which is based on a new definition of the effort of the material domain, to be called “total material potential”. To demonstrate this, the TBG is successfully applied to a compressible, one-dimensional matter-flow, which convects momentum and heat (entropy).