# .ThermoPower.Water.BaseClasses.PumpBase

## Information

This is the base model for the Pump and PumpMech pump models.

The model describes a centrifugal pump, or a group of Np identical pumps in parallel. The pump model is based on the theory of kinematic similarity: the pump characteristics are given for nominal operating conditions (rotational speed and fluid density), and then adapted to actual operating condition, according to the similarity equations.

In order to avoid singularities in the computation of the outlet enthalpy at zero flowrate, the thermal capacity of the fluid inside the pump body can be taken into account.

The model can either support reverse flow conditions or include a built-in check valve to avoid flow reversal.

Modelling options

The nominal hydraulic characteristic (head vs. volume flow rate) is given by the the replaceable function flowCharacteristic.

The pump energy balance can be specified in two alternative ways:

• usePowerCharacteristic = false (default option): the replaceable function efficiencyCharacteristic (efficiency vs. volume flow rate in nominal conditions) is used to determine the efficiency, and then the power consumption. The default is a constant efficiency of 0.8.
• usePowerCharacteristic = true: the replaceable function powerCharacteristic (power consumption vs. volume flow rate in nominal conditions) is used to determine the power consumption, and then the efficiency.

Several functions are provided in the package Functions.PumpCharacteristics to specify the characteristics as a function of some operating points at nominal conditions.

Depending on the value of the checkValve parameter, the model either supports reverse flow conditions, or includes a built-in check valve to avoid flow reversal.

If the in_Np input connector is wired, it provides the number of pumps in parallel; otherwise, Np0 parallel pumps are assumed.

It is possible to take into account the heat capacity of the fluid inside the pump by specifying its volume V at nominal conditions; this is necessary to avoid singularities in the computation of the outlet enthalpy in case of zero flow rate. If zero flow rate conditions are always avoided, this dynamic effect can be neglected by leaving the default value V = 0, thus avoiding a fast state variable in the model.

The CheckValve parameter determines whether the pump has a built-in check valve or not.

If computeNPSHa = true, the available net positive suction head is also computed; this requires a two-phase medium model to provide the fluid saturation pressure.

## Revisions

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