modelPowerSimplified

Power calculation comparison among three mover types, using simplified power computation for m_flow and dp
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Extends from Modelica.Icons.Example (Icon for runnable examples).

Information

This example compares the power consumed by pumps that take three different control signals. Each pump has identical mass flow rate and pressure rise.

Note that for the instances BuildingSystems.Fluid.Movers.FlowControlled_dp and BuildingSystems.Fluid.Movers.FlowControlled_m_flow, we had to assign the efficiencies (otherwise the default constant efficiency of 0.7 would have been used). In these models, the power consumption is computed using similarity laws, but using the mass flow rate as opposed to the speed, because speed is not known in these two models. This is an approximation at operating points in which the speed is different from the nominal speed y_nominal because similarity laws are valid for speed and not for mass flow rate.

The figure below shows the approximation error for the power calculation where the speed y differs from the nominal speed ynominal.

image

Parameters

TypeNameDefaultDescription
Modelica.Units.SI.MassFlowRatem_flow_nominal3Nominal mass flow rate
BuildingSystems.Fluid.Movers.Data.Pumps.Wilo.Stratos30slash1to8perPump performance data

Components

TypeNameDefaultDescription
BuildingSystems.Fluid.Movers.SpeedControlled_ypump_yPump with normalised speed y as control signal
BuildingSystems.Fluid.Movers.FlowControlled_dppump_dpPump with pressure rise as control signal
BuildingSystems.Fluid.Movers.FlowControlled_m_flowpump_m_flowPump with mass flow rate as control signal
BuildingSystems.Fluid.Sources.Boundary_pTbouPressure source
BuildingSystems.Fluid.FixedResistances.PressureDropresFlow resistance
BuildingSystems.Fluid.Sources.Boundary_pTsink
Modelica.Blocks.Sources.RampyRamp for pump normalised speed control signal
Modelica.Blocks.Sources.RealExpressiondpSetPressure rise across pump
Modelica.Blocks.Sources.RealExpressionm_flowSetPump mass flow rate
Modelica.Blocks.Routing.Multiplex3result

Contents

NameDescription
MediumMedium model

Revisions

  • March 21, 2023, by Hongxiang Fu:
    Replaced the pump with Nrpm signal with one with y signal. This is for IBPSA, #1704.
  • March 8, 2022, by Hongxiang Fu:
    Refactored the model by replacing not use_powerCharacteristic with the enumeration BuildingSystems.Fluid.Movers.BaseClasses.Types.HydraulicEfficiencyMethod. This is for #2668.
  • October 15, 2021, by Hongxiang Fu:
    Fixed the image in the documentation which was cut off at the y-axis. This is for IBPSA, #1533.
  • March 11, 2016, by Michael Wetter:
    Revised implementation by assigning the data record directly in the instances pump_dp and pump_m_flow, because using a parameter and assigning this parameter leads in OpenModelica to the error message expected subtype of record BuildingSystems.Fluid.Movers.Data.Generic.
  • March 2, 2016, by Filip Jorissen:
    Revised implementation for #417.
  • November 5, 2015, by Michael Wetter:
    Changed parameters since the power is no longer a parameter for the movers that take mass flow rate or head as an input. This is for issue 457.
  • November 22, 2014, by Michael Wetter:
    Revised implementation.