modelThermostaticMixingValve

A model for a thermostatic mixing valve

Information

This model implements a thermostatic mixing valve, which uses a PI feedback controller to mix hot and cold fluid to achieve a specified mixed water outlet temperature.

If the mixed water temperature cannot be provided within a tolerance of relTol, averaged over the whole simulation period, then an assertion warning will be written at the end of the simulation.

Parameters

Type	Name	Default	Description
Modelica.Units.SI.MassFlowRate	mMix_flow_nominal		Nominal mixed water flow rate to fixture
Buildings.Controls.OBC.CDL.Types.SimpleController	controllerType	Buildings.Controls.OBC.CDL.Types.SimpleController.PI	Type of controller
Control gains
Real	k	1	Gain of controller
Real	Ti	0.5	Time constant of integrator block
Real	Td	0.1	Time constant of derivative block
Advanced
Real	relTol	0.005	Relative tolerance on energy balance, if not met, a warning will be issued at end of simulation

Connectors

Type	Name	Description
Modelica.Fluid.Interfaces.FluidPort_a	port_hot	Port for hot water supply
Modelica.Fluid.Interfaces.FluidPort_a	port_col	Port for domestic cold water supply
Modelica.Blocks.Interfaces.RealInput	TMixSet	Temperature setpoint of mixed water outlet
Modelica.Blocks.Interfaces.RealInput	yMixSet	Mixed water fractional flow rate at TMixSet, as fraction of mMix_flow_nominal

Components

Type	Name	Description
Buildings.Fluid.Sensors.TemperatureTwoPort	senTHot	Hot water temperature
Buildings.Fluid.Sensors.TemperatureTwoPort	senTCol	Cold water temperature
Buildings.Fluid.Sensors.TemperatureTwoPort	senTMix	Mixed water temperature
Buildings.Controls.OBC.CDL.Reals.PID	conPID
Buildings.Controls.OBC.CDL.Reals.Divide	ratEne	Ratio of actual over required energy (must be near 1 if load is satisfied)
Buildings.Fluid.FixedResistances.Junction	jun	Mixing of hot water and cold water

Name	Description
Medium	Water media model
EnergyMeterprotected	Block that outputs integrated energy, bounded away from zero

Revisions

December 7, 2023, by David Blum:
Added junction.
October 17, 2023, by Michael Wetter:
Revised implementation.
September 11, 2023 by David Blum:
Updated for release.
June 16, 2022 by Dre Helmns:
Initial Implementation.