modelDecouplingMixing

Information

This model represents a cooling system where the configuration Buildings.Fluid.HydronicConfigurations.ActiveNetworks.Decoupling is used in conjunction with Buildings.Fluid.HydronicConfigurations.PassiveNetworks.SingleMixing. The combined configuration serves as the interface between a variable flow primary circuit and a variable flow consumer circuit. The primary circuit has a constant supply temperature. The consumer circuit has a varying supply temperature set point that is reset based on the terminal valve opening, with the most open valve being kept 90% open.

Note the following settings.

• con1.dp1_nominal=con.dpBal3_nominal which is used to size the control valve and the pump of the mixing configuration, and avoids a reverse flow in the bypass at partial load due to the opposing differential pressure created by the decoupling configuration. See Buildings.Fluid.HydronicConfigurations.PassiveNetworks.Examples.SingleMixingOpenLoop for further details on that behavior.
• The controller resT2 that is used to reset the secondary supply temperature uses y_reset=1 which yields the design supply temperature at the time when the controller is enabled. Otherwise there is a significant delay in satisfying the load, followed by a large overshoot, and the control loop is hard to tune.

The fact that the load seems unmet at partial load (see plot #4) is due to the load model that does not guarantee a linear variation of the load with the input signal in cooling mode, see Buildings.Fluid.HydronicConfigurations.ActiveNetworks.Examples.BaseClasses.Load.

Components

Revisions

• June 30, 2022, by Antoine Gautier:
  First implementation.