modelStaticReset

Comparing different computation paths with a static pressure reset
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Extends from Modelica.Icons.Example (Icon for runnable examples).

Information

This example model compares the three power computation methods in a scenario where the fan performance (P vs. V̇) is examined to verify savings of a static pressure reset. The fan speed is controlled to track the duct static pressure at a point downstream while the damper (representing a VAV box) moves from fully closed to fully open. The system was described in Englander and Norford (1992). The fan data are implemented in BuildingSystems.Fluid.Movers.Examples.Data.EnglanderNorford1992.

  • The first fan uses the fan curve to estimate the shaft power at reduced speed.
  • The second fan uses the Euler number and its correlation to estimate the hydraulic efficiency.
  • The third fan assumes a constant hydraulic efficiency.

In the results, P computed from the Euler number and from the power curve agree on the trend of P vs. V̇. Both of them are also able to prevent P from incorrectly going to zero as V̇ approaches zero, which the method with constant efficiency failed.

References

Englander, S. L., and L. K. Norford. "Saving fan energy in VAV systems- part 1: analysis of a variable-speed-drive retrofit." ASHRAE Winter Meeting, Anaheim, CA, USA, 01/25-29/92. 1992.

Parameters

TypeNameDefaultDescription
Modelica.Units.SI.VolumeFlowRateV_flow_nominal21.8Nominal volumetric flow rate of the system
Modelica.Units.SI.MassFlowRatem_flow_nominalV_flow_nominal/1.2Nominal mass flow rate of the system
Modelica.Units.SI.PressureDifferencedp_nominal1244.2Nominal pressure rise of the system

Components

TypeNameDefaultDescription
BuildingSystems.Fluid.Movers.SpeedControlled_yfan1Fan using power curves
BuildingSystems.Fluid.Movers.SpeedControlled_yfan2Fan using the Euler number
BuildingSystems.Fluid.Movers.SpeedControlled_yfan3Fan using constant efficiency
BuildingSystems.Fluid.Sources.Boundary_pTsouBoundary
BuildingSystems.Fluid.Sources.Boundary_pTsinBoundary
BuildingSystems.Fluid.FixedResistances.PressureDropdp11Duct pressure drop before the static pressure measurement point
BuildingSystems.Fluid.FixedResistances.PressureDropdp12Duct pressure drop after the static pressure measurement point
BuildingSystems.Fluid.FixedResistances.PressureDropdp21Duct pressure drop before the static pressure measurement point
BuildingSystems.Fluid.FixedResistances.PressureDropdp22Duct pressure drop after the static pressure measurement point
BuildingSystems.Fluid.FixedResistances.PressureDropdp31Duct pressure drop before the static pressure measurement point
BuildingSystems.Fluid.FixedResistances.PressureDropdp32Duct pressure drop after the static pressure measurement point
BuildingSystems.Fluid.Sensors.RelativePressurepDucSta1Duct static pressure
BuildingSystems.Fluid.Sensors.RelativePressurepDucSta2Duct static pressure
BuildingSystems.Fluid.Sensors.RelativePressurepDucSta3Duct static pressure
BuildingSystems.Controls.Continuous.LimPIDconPID1PI controller
BuildingSystems.Controls.Continuous.LimPIDconPID2PI controller
BuildingSystems.Controls.Continuous.LimPIDconPID3PI controller
Modelica.Blocks.Math.Gaingai1Gain
Modelica.Blocks.Math.Gaingai2Gain
Modelica.Blocks.Math.Gaingai3Gain
Modelica.Blocks.Sources.ConstantyDuct static pressure setpoint (normalised)
Actuators.Dampers.ExponentialdamExp1Damper representing a VAV box
Actuators.Dampers.ExponentialdamExp2Damper representing a VAV box
Actuators.Dampers.ExponentialdamExp3Damper representing a VAV box
Modelica.Blocks.Sources.RampyDamRamp input for damper position

Contents

NameDescription
Medium

Revisions

  • January 24, 2022, by Hongxiang Fu and David Blum:
    First implementation. This is for #2668.