.Annex60.Fluid.Movers.BaseClasses.PartialFlowMachine

Information

This is the base model for fans and pumps. It provides an interface between the equations that compute head and power consumption, and the implementation of the energy and pressure balance of the fluid.

Optionally, the fluid volume is computed using a dynamic balance or a steady-state balance.

The parameter addPowerToMedium determines whether any power is added to the fluid. The default is addPowerToMedium=true, and hence the outlet enthalpy is higher than the inlet enthalpy if the flow device is operating. The setting addPowerToMedium=false is physically incorrect (since the flow work, the flow friction and the fan heat do not increase the enthalpy of the medium), but this setting does in some cases lead to simpler equations and more robust simulation, in particular if the mass flow is equal to zero.

Revisions

• December 2, 2016, by Michael Wetter:
  Removed min attribute as otherwise numerical noise can cause the assertion on the limit to fail.
  This is for #606.
• November 3, 2016, by Michael Wetter:
  Set start value for VMachine_flow to avoid a warning in Annex60.Fluid.Movers.Examples.MoverContinuous.
• July 29, 2016, by Michael Wetter:
  Made Extractor protected so that it can be removed later with a backwards compatible change.
• July 19, 2016, by Filip Jorissen:
  Created custom implementation for extractor. This is for #498.
• June 16, 2016, by Filip Jorissen:
  Switched position of mixing volume and mass flow rate sensor. This is to have a consistent operating point tuple of dp and m_flow when having compressible flow. This is for #458.
• February 19, 2016, by Michael Wetter and Filip Jorissen:
  Refactored model to make implementation clearer. This model now includes code for both speed and flow prescribed models, eliminating the need for an additional level of partial models. This is for #417.
• Removed the parameter dynamicBalance. This is for #411.
• November 19, 2015, by Michael Wetter:
  Removed assignment of parameter showDesignFlowDirection in extends statement. This is for #349. Removed assignment of min and max attributes of the port mass flow rate as this is already done in the base class. Removed import statement.
• April 2, 2015, by Filip Jorissen:
  Added code for supporting stage input and constant input. Added code for displaying constant set point in symbol.
• January 24, 2015, by Michael Wetter:
  Propagated m_flow_small of instance vol and made all its parameters final.
• May 25, 2011, by Michael Wetter:
  Revised implementation of energy balance to avoid having to use conditionally removed models.
• July 29, 2010, by Michael Wetter:
  Reduced fan time constant from 10 to 1 second.
• July 27, 2010, by Michael Wetter:
  Redesigned model to fix bug in medium balance.
• March 24 2010, by Michael Wetter:
  First implementation.