modelThermostaticValve
Extends from AixLib.Obsolete.BaseClasses.ObsoleteModel (Icon for classes that are obsolete and will be removed in later versions).
Information
Overview
Thermostatic valve model.
Concept
The thermostatic valve model is designed as a pump controller. The mass flow set value is calculated based on nominal mass flow and the temperature difference between the setpoint and actual value.
The valve opening characteristic is described by the function
valveCharacteristic, linear characteristic by default,
can be replaced by any user-defined function. Equal percentage with
customizable rangeability and an optimal characteristic are already
provided by the library.
With the optional parameter "filteredOpening", the opening can be filtered with a second order, criticalDamping filter so that the opening demand is delayed by parameter "riseTime". The filtered opening is then available via the output signal "opening_filtered" and is used to control the valve equations. This approach approximates the driving device of a valve. The "riseTime" parameter is used to compute the cut-off frequency of the filter by the equation: f_cut = 5/(2*pi*riseTime). It defines the time that is needed until opening_filtered reaches 99.6 % of a step input of opening.
Example Results
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | k | 0.1 | Gain of controller |
| Modelica.Units.SI.Time | Ti | 1000 | Time constant of Integrator block |
| Modelica.Units.SI.MassFlowRate | dotm_nominal | 0.5 | |
| Nominal operating point | |||
| Real | opening_nominal | 1 | Nominal opening |
| Filtered opening | |||
| Boolean | filteredOpening | false | = true, if opening is filtered with a 2nd order CriticalDamping filter |
| Modelica.Units.SI.Time | riseTime | 1 | Rise time of the filter (time to reach 99.6 % of an opening step) |
| Real | leakageOpening | 0.001 | The opening signal is limited by leakageOpening (to improve the numerics) |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Blocks.Interfaces.RealOutput | dotm_set | ||
| Modelica.Blocks.Interfaces.RealInput | T_set | Valve position in the range 0..1 | |
| Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a | T_room |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Thermal.HeatTransfer.Sensors.TemperatureSensor | temperatureSensor | ||
| Modelica.Blocks.Continuous.LimPID | PID | ||
| FastHVAC.Components.Valves.BaseClases.HysteresisValve | hysteresisValve | ||
| Modelica.Blocks.Sources.RealExpression | realExpression | ||
| Modelica.Blocks.Math.Product | product |
Contents
| Name | Description |
|---|---|
 valveCharacteristic | |
 MinLimiterprotected | Limit the signal above a threshold |
Revisions
-
April 13, 2017 Tobias Blacha:
Moved into AixLib -
February 19, 2015 by Konstantin Finkbeiner:
Implemented