modelMixingBox
Outside air mixing box with interlocked air dampers
Extends from IBPSA.Fluid.Actuators.BaseClasses.ActuatorSignal (Partial model that implements the filtered opening for valves and dampers).
Information
Model of an outside air mixing box with air dampers.
Set y=0 to close the outside air and exhast air dampers.
If dp_nominalIncludesDamper=true, then the parameter dp_nominal
is equal to the pressure drop of the damper plus the fixed flow resistance at the nominal
flow rate.
If dp_nominalIncludesDamper=false, then dp_nominal
does not include the flow resistance of the air damper.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | use_deltaM | true | Set to true to use deltaM for turbulent transition, else ReC is used |
| Real | deltaM | 0.3 | Fraction of nominal mass flow rate where transition to turbulent occurs |
| Modelica.SIunits.Velocity | v_nominal | 1 | Nominal face velocity |
| Boolean | roundDuct | false | Set to true for round duct, false for square cross section |
| Real | ReC | 4000 | Reynolds number where transition to turbulent starts |
| Dynamics › Filtered opening | |||
| Boolean | use_inputFilter (from ActuatorSignal) | true | = true, if opening is filtered with a 2nd order CriticalDamping filter |
| Modelica.SIunits.Time | riseTime (from ActuatorSignal) | 120 | Rise time of the filter (time to reach 99.6 % of an opening step) |
| Integer | order (from ActuatorSignal) | 2 | Order of filter |
| Modelica.Blocks.Types.Init | init (from ActuatorSignal) | Modelica.Blocks.Types.Init.InitialOutput | Type of initialization (no init/steady state/initial state/initial output) |
| Real | y_start (from ActuatorSignal) | 1 | Initial value of output |
| Assumptions | |||
| Boolean | allowFlowReversal | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| Nominal condition | |||
| Boolean | dp_nominalIncludesDamper | false | set to true if dp_nominal includes the pressure loss of the open damper |
| Modelica.SIunits.MassFlowRate | mOut_flow_nominal | Mass flow rate outside air damper | |
| Modelica.SIunits.PressureDifference | dpOut_nominal | Pressure drop outside air leg | |
| Modelica.SIunits.MassFlowRate | mRec_flow_nominal | Mass flow rate recirculation air damper | |
| Modelica.SIunits.PressureDifference | dpRec_nominal | Pressure drop recirculation air leg | |
| Modelica.SIunits.MassFlowRate | mExh_flow_nominal | Mass flow rate exhaust air damper | |
| Modelica.SIunits.PressureDifference | dpExh_nominal | Pressure drop exhaust air leg | |
| Advanced | |||
| Boolean | from_dp | true | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearized | false | = true, use linear relation between m_flow and dp for any flow rate |
| Boolean | use_constant_density | true | Set to true to use constant density for flow friction |
| Damper coefficients | |||
| Real | a | -1.51 | Coefficient a for damper characteristics |
| Real | b | 0.105*90 | Coefficient b for damper characteristics |
| Real | yL | 15/90 | Lower value for damper curve |
| Real | yU | 55/90 | Upper value for damper curve |
| Real | k0 | 1E6 | Flow coefficient for y=0, k0 = pressure drop divided by dynamic pressure |
| Real | k1 | 0.45 | Flow coefficient for y=1, k1 = pressure drop divided by dynamic pressure |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Blocks.Interfaces.RealInput | y (from ActuatorSignal) | Actuator position (0: closed, 1: open) | |
| Modelica.Blocks.Interfaces.RealOutput | y_actual (from ActuatorSignal) | Actual valve position | |
| Modelica.Fluid.Interfaces.FluidPort_a | port_Out | Fluid connector a (positive design flow direction is from port_a to port_b) | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_Exh | Fluid connector b (positive design flow direction is from port_a to port_b) | |
| Modelica.Fluid.Interfaces.FluidPort_a | port_Ret | Fluid connector a (positive design flow direction is from port_a to port_b) | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_Sup | Fluid connector b (positive design flow direction is from port_a to port_b) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| VAVBoxExponential | damOA | ||
| VAVBoxExponential | damExh | Exhaust air damper | |
| VAVBoxExponential | damRec | Recirculation air damper | |
| Modelica.Blocks.Sources.Constant | uni | Unity signal | |
| Modelica.Blocks.Math.Add | add | Adder |
Contents
| Name | Description |
|---|---|
 Medium | Medium in the component |
Revisions
-
March 24, 2017, by Michael Wetter:
RenamedfilteredInputtouse_inputFilter.
This is for #665. -
March 22, 2017, by Michael Wetter:
Removed the assignments ofAOut,AExhandARecas these are done in the damper instance using a final assignment of the parameter. This allows scaling the model withm_flow_nominal, which is generally known in the flow leg, andv_nominal, for which a default value can be specified.
This is for #544. -
January 22, 2016, by Michael Wetter:
Corrected type declaration of pressure difference. This is for #404. -
December 14, 2012 by Michael Wetter:
Renamed protected parameters for consistency with the naming conventions. -
February 14, 2012 by Michael Wetter:
Added filter to approximate the travel time of the actuator. -
February 3, 2012, by Michael Wetter:
Removed assignment ofm_flow_smallas it is no longer used in its base class. -
February 23, 2010 by Michael Wetter:
First implementation.