Pump Power

Used to calculated flow, power, and pump efficiency.

None

This is the default method. It performs no calculations and has no slots associated with it. This method is not a valid method and an error is flagged if the user has selected it.

Unit Pump Power

Calculates pump power and pumped flow. First, the efficiency of all the different pump types is determined. Then flow and power are calculated based on the properties that are given.

There are no slots specific to this method.

Method Details

1. The first step in the method is to determine the Operating Head. Operating head is calculated by the user method selected in the Tailwater category. Then, the efficiencies of all pump types at the given Operating Head are calculated. Efficiency is calculated as power divided by flow where power and flow are determined from interpolation of the Head vs Pump Power and Head vs Pump Flow tables, respectively, for each pump type.

2. To solve for Pump Power and Inflow, different sets of calculations are performed depending upon the slots input by the user.

– If Pumps Used is given, the following calculations are performed (pumps are added in the best efficiency order):

1. For each pump used, the flow and power are calculated from the Head vs Pump Flow and Head vs Pump Power tables.

2. Pumped Flow is set as the sum of the flows through each pump. Pump Power is set as the sum of the power used by each pump.

3. Pump Energy is calculated as the product of Pump Power and the length of the timestep.

– If Pumped Flow is given, the following calculations are performed:

1. Pump types are added (in the order of most efficient to least efficient) until the Pumped Flow has been met or all available pumps have been used.

2. When the Pumped Flow is exceeded, the least efficient pump type is interpolated to determine Pump Power and Pumps Used so that the exact target Pumped Flow is met.

3. If the Pumped Flow cannot be met by all available pumps, the run terminates with an error message that the specified Pumped Flow cannot be met.

4. Pump Energy is calculated as the product of Pump Power and the length of the timestep.

– If Pump Power is input by the user, a similar approach is taken to the case where Pumped Flow is input. Entire types of pumps are added until the given Pump Power has been met. When the target Pump Power has been exceeded, linear interpolation is done on the least efficient pump type so that the pump power is met exactly. If all the pump types cannot meet the target Pump Power, the run terminates with an error message that the specified Pump Power cannot be met.

3. Finally, the Power Coefficient is calculated as Pumped Power divided by Inflow.

Revised: 01/11/2023