Thermodynamic Bond Graphs and the Problem of Thermal Inertance

It is shown that an isolated thermal inertance does not obey the second law of thermodynamics. Consequently, such an element should not be used in physical systems theory. To eliminate the structural gap in the thermal domain of current physical systems theory, a new framework is introduced using Bond Graph concepts. These Thermodynamic Bond Graphs are the result of synthesis of methods used in thermodynamics and in mechanics

Decomposition of multiport elements in a revised multibond graph notation

Decomposition rules are derived for multiport-transformers, -resistors, -storage elements and -gyrators into 1- and 2-port elements, junctions and bonds. It appears that it is useful to extend the vectorbond, or rather multibond, notation recently proposed by the author with a “multibond array”. Canonical forms are introduced on the basis of minimal realization, because decompositions of multiport elements are not unique. A new type of coupling factor (“directed coupling factor”) is introduced for multiport-resistors and capacitors