The model represents a pump in a circuit system. The characteristic of the pump is defined through the nominal operating point. The nominal mass flow rate, m_flowNom, and the nominal power, PNom, of the pump are defined at nominal pump speed, wNom. The nominal mass flow rate of the medium is a linear function of the pump speed. The relation between the mass flow rate and the pump speed is represented in figure 1. The curve mass flow represents the mass flow rate of the pump and the mark OP indicates the nominal operating point of the pump.

Figure 1: Relation between the mass flow rate in the pump and the pump speed.

The nominal power of the pump is modeled as a cubic function of the pump speed. The relation between the power and the pump speed is representet in figure 2. The curve power represents the power of the pump and the mark OP indicates the nominal operating point of pump.

Figure 2: Relation between the power of a pump and the pump speed.

Boundary condition

If the model of the pump is operated then the mass flow rate is strictly defined by the operating curve. The mass flow rate of the pump is not dependent on the pressure loss in a pipeline or a circuit. The mechanical losses of the bearings of the pump are not considered. The pump can be driven in positive and negative speed direction whereas the mass flow and power characteristic in both directions have the same absolute value.