Digital systems
Relations for thermal, hydraulic and electrical systems

The presented model of thermal system is very simplistic, compared to reality (e.g. a heated room). Real models have more complicated structure and they are usually of higher order. In our model, the resistor R1 stands for a heating, a thermal resistance of heater, and the resistor R2 corresponds to heating losses - lower the resistance, greater the loss. Well insulated building typically does have a large resistance values. Capacitance of C represents thermal capacity, i.e. amount of heat, accumulated at certain temperature. It is given by volume of air, partly a walls and heating elements as well.

Electric circuit with two voltage sources corresponds to a hydraulic system with two large basins with different level and it is an analogy of thermal system (we must not forget the square root characteristic of flux on level difference in case of hydraulic system).

Fig. 8.8: Hydraulic system with two large