Simple fan resp. pump where characteristic is dependent on shaft's speed,
torque * speed = pressure increase * volume flow (without losses)
Pressure increase versus volume flow is defined by a linear function,
from dp0(V_flow=0) to V_flow0(dp=0).
The axis intersections vary with speed as follows:
Coolant's temperature and enthalpy flow are not affected.
Setting parameter m (mass of medium within fan/pump) to zero
leads to negligence of temperature transient cv*m*der(T).
Thermodynamic equations are defined by BaseClasses.TwoPort.