Modelling of thermal systems from technical sketches to equations

Modellers ands users of simulation softwares need to agree on a standard way to state the physical bases of their models The proposals presented in this paper are not new; they refer to the very classical way of describing thermodynamical systems. The basic piece of this description is the reference volume which may be "crossed" by mass and energy flows and which may also have some (mass and/or energy) "capacity". R-C networks are nothing more than "degenerate" or "simplified" sets of reference volumes. All the buildings and HVAC subsystems may be subdivided into sets of interconnected volumes. Only some elementary examples are given hereafter ...