.Buildings.Fluid.DXSystems.Cooling.AirSource.Validation.SingleSpeedPLR

Information

This model validates the model Buildings.Fluid.DXSystems.Cooling.AirSource.SingleSpeed.

The difference in results of T_Out and X_Out at the beginning and end of the simulation is because the mass flow rate is zero. For zero mass flow rate, EnergyPlus assumes steady state condition, whereas the Modelica model is a dynamic model and hence the properties at the outlet are equal to the state variables of the model.

The EnergyPlus results were generated using the example file DXCoilSystemAuto.idf from EnergyPlus 7.1.

The EnergyPlus results were generated using the example file DXCoilSystemAuto.idf from EnergyPlus 7.1. On the summer design day, the PLR is below 1. A similar effect has been achieved in this example by turning on the coil only for the period during which it run in EnergyPlus. This results in on-off cycle and fluctuating results. To compare the results, the Modelica outputs are averaged over 3600 seconds, and the EnergyPlus outputs are used with a zero order delay to avoid the time shift in results.

Note that EnergyPlus mass fractions (X) are in mass of water vapor per mass of dry air, whereas Modelica uses the total mass as a reference. Hence, the EnergyPlus values are corrected by dividing them by 1+X.

Contents

Name	Description
Medium	Medium model

Revisions

• April 5, 2023, by Karthik Devaprasad and Xing Lu:
  Updated class name to differentiate from validation models for heating coils.
  Updated connect statements to reflect change in input instance on sinSpeDX from TConIn to TOut.
  Updated comments and formatting for readability.
• January 22, 2016, by Michael Wetter:
  Corrected type declaration of pressure difference. This is for #404.
• September 24, 2015 by Michael Wetter:
  Implemented UnitDelay to avoid a translation warning because UnitDelay.firstTrigger does not set the fixed attribute in MSL 3.2.1.
• June 9, 2015, by Michael Wetter:
  Corrected wrong link to run script.
• December 22, 2014 by Michael Wetter:
  Removed Modelica.Fluid.System to address issue #311.
• September 4, 2012 by Michael Wetter:
  Modified example to avoid having to access protected data.
• August 20, 2012 by Kaustubh Phalak:
  First implementation.