.Buildings.Fluid.MixingVolumes.Validation.MixingVolumeMassFlow

Information

This model demonstrates the use of the mixing volume with air flowing into and out of the volume.

The initial conditions for the volume is declared as fixed initial values for the energy dynamics, but free initial conditions for the mass dynamics. The reason for leaving the initial conditions unspecified for the mass dynamics is that the sink bou declares the pressure of the fluid. As there is no flow resistance between that boundary condition and the volume, the volume has the same pressure. Therefore, specifying an initial condition for the mass dynamics would yield to an overspecified initial value problem for the pressure of the medium.

Contents

Revisions

• January 22, 2016, by Michael Wetter:
  Corrected type declaration of pressure difference. This is for #404.
• March 27, 2015 by Michael Wetter:
  Set the mass dynamics of the volume to Modelica.Fluid.Types.Dynamics.DynamicFreeInitial to avoid an overspecified but consistent initial value problem. The previous implementation caused a warning in Dymola 2015 FD01, and caused in Dymola 2016 beta 2 to not translate the model. The problem was that the boundary condition and the volume both declared an equation for the initial pressure.
• October 12, 2009 by Michael Wetter:
  First implementation.