Hot fluid convection systems with true and pseudo bondgraphs

Combining the point of view of power and control engineering, convection in fluid pipes is reticulated by pseudo bonds with mass flow and enthalpy flux. The author writes a power balance for the walls of heat exchangers and for thermal fluid machines. In a system, such components are placed between coupling capacitors, which determine pressure and temperature from stored mass and enthalpy. In the machine, incoming enthalpy flux follows from mass flow and upstream temperature, outgoing enthalpy flux from the power balance. Mechanical power follows from the torque as function of shaft angular frequency and mass flow. One such equation is used to simulate the start a compressor, followed by variation of load and cooling