Buildings.Fluids.Actuators.Dampers

Package with air damper models

Information

This package contains components models for air dampers. For motor models, see Buildings.Fluids.Actuators.Motors.

Package Content

Name Description

Exponential Air damper with exponential opening characteristics

OAMixingBoxMinimumDamper Outside air mixing box with parallel damper for minimum outside air flow rate

VAVBoxExponential VAV box with a fixed resistance plus a damper model withe exponential characteristics

Name	Description
Exponential	Air damper with exponential opening characteristics
OAMixingBoxMinimumDamper	Outside air mixing box with parallel damper for minimum outside air flow rate
VAVBoxExponential	VAV box with a fixed resistance plus a damper model withe exponential characteristics

Buildings.Fluids.Actuators.Dampers.Exponential

Air damper with exponential opening characteristics

Buildings.Fluids.Actuators.Dampers.Exponential

Information

This model is an air damper with flow coefficient that is an exponential function of the opening angle. The model is as in ASHRAE 825-RP. A control signal of y=0 means the damper is closed, and y=1 means the damper is open. This is opposite of the implementation of ASHRAE 825-RP, but used here for consistency within this library.

For yL < y < yU, the damper characteristics is

  k = exp(a+b*(1-y)).

Outside this range, the damper characteristic is defined by a quadratic polynomial that matches the damper resistance at y=0 and y=yL or y=yU and y=1, respectively. In addition, the polynomials are such that k(y) is differentiable in y and the derivative is continuous.

ASHRAE 825-RP lists the following parameter values as typical:

opposed blades single blades

yL 15/90 15/90

yU 55/90 65/90

k0 1E6 1E6

k1 0.2 to 0.5 0.2 to 0.5

a -1.51 -1.51

b 0.105*90 0.0842*90

References

P. Haves, L. K. Norford, M. DeSimone and L. Mei, A Standard Simulation Testbed for the Evaluation of Control Algorithms & Strategies, ASHRAE, Final Report 825-RP, Atlanta, GA.

Extends from Buildings.Fluids.Actuators.BaseClasses.PartialDamperExponential (Partial model for air dampers with exponential opening characteristics).

Parameters

Type Name Default Description

replaceable package Medium Modelica.Media.Interfaces.Pa... Medium in the component

Area A Face area [m2]

Boolean roundDuct false Set to true for round duct, false for square cross section

Real ReC 4000 Reynolds number where transition to laminar starts

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

Nominal condition

MassFlowRate m0_flow Nominal mass flow rate [kg/s]

Initialization

Real kDam.start 1 Flow coefficient for damper, k=m_flow/sqrt(dp), with unit=(kg*m)^(1/2)

Assumptions

Boolean allowFlowReversal system.allowFlowReversal = true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Advanced

AbsolutePressure dp_start 0.01*system.p_start Guess value of dp = port_a.p - port_b.p [Pa]

MassFlowRate m_flow_start system.m_flow_start Guess value of m_flow = port_a.m_flow [kg/s]

MassFlowRate m_flow_small 1E-4*m0_flow Small mass flow rate for regularization of zero flow [kg/s]

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

Diagnostics

Boolean show_T true = true, if temperatures at port_a and port_b are computed

Boolean show_V_flow true = true, if volume flow rate at inflowing port is computed

Type	Name	Default	Description
replaceable package Medium	Modelica.Media.Interfaces.Pa...	Medium in the component
Area	A		Face area [m2]
Boolean	roundDuct	false	Set to true for round duct, false for square cross section
Real	ReC	4000	Reynolds number where transition to laminar starts
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
Nominal condition
MassFlowRate	m0_flow		Nominal mass flow rate [kg/s]
Initialization
Real	kDam.start	1	Flow coefficient for damper, k=m_flow/sqrt(dp), with unit=(kg*m)^(1/2)
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
AbsolutePressure	dp_start	0.01*system.p_start	Guess value of dp = port_a.p - port_b.p [Pa]
MassFlowRate	m_flow_start	system.m_flow_start	Guess value of m_flow = port_a.m_flow [kg/s]
MassFlowRate	m_flow_small	1E-4*m0_flow	Small mass flow rate for regularization of zero flow [kg/s]
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
Diagnostics
Boolean	show_T	true	= true, if temperatures at port_a and port_b are computed
Boolean	show_V_flow	true	= true, if volume flow rate at inflowing port is computed

Connectors

Type Name Description

FluidPort_a port_a Fluid connector a (positive design flow direction is from port_a to port_b)

FluidPort_b port_b Fluid connector b (positive design flow direction is from port_a to port_b)

input RealInput y Damper position (0: closed, 1: open)

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
input RealInput	y	Damper position (0: closed, 1: open)

Modelica definition

model Exponential 
  "Air damper with exponential opening characteristics"
  extends Buildings.Fluids.Actuators.BaseClasses.PartialDamperExponential;
equation 
  k = kDam "flow coefficient for resistance base model";
end Exponential;

Buildings.Fluids.Actuators.Dampers.OAMixingBoxMinimumDamper

Outside air mixing box with parallel damper for minimum outside air flow rate

Buildings.Fluids.Actuators.Dampers.OAMixingBoxMinimumDamper

Information

Model of an outside air mixing box with air dampers and a flow path for the minimum outside air flow rate.

Extends from Buildings.BaseClasses.BaseIcon (Base icon).

Parameters

Type Name Default Description

Area AOutMin Face area minimum outside air damper [m2]

Area AOut Face area outside air damper [m2]

Area AExh Face area exhaust air damper [m2]

Area ARec Face area recirculation air damper [m2]

Nominal condition

MassFlowRate m0OutMin_flow Mass flow rate minimum outside air damper [kg/s]

Pressure dp0OutMin Pressure drop minimum outside air leg (without damper) [Pa]

MassFlowRate m0Out_flow Mass flow rate outside air damper [kg/s]

Pressure dp0Out Pressure drop outside air leg (without damper) [Pa]

MassFlowRate m0Rec_flow Mass flow rate recirculation air damper [kg/s]

Pressure dp0Rec Pressure drop recirculation air leg (without damper) [Pa]

MassFlowRate m0Exh_flow Mass flow rate exhaust air damper [kg/s]

Pressure dp0Exh Pressure drop exhaust air leg (without damper) [Pa]

Assumptions

Boolean allowFlowReversal system.allowFlowReversal = true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Type	Name	Default	Description
Area	AOutMin		Face area minimum outside air damper [m2]
Area	AOut		Face area outside air damper [m2]
Area	AExh		Face area exhaust air damper [m2]
Area	ARec		Face area recirculation air damper [m2]
Nominal condition
MassFlowRate	m0OutMin_flow		Mass flow rate minimum outside air damper [kg/s]
Pressure	dp0OutMin		Pressure drop minimum outside air leg (without damper) [Pa]
MassFlowRate	m0Out_flow		Mass flow rate outside air damper [kg/s]
Pressure	dp0Out		Pressure drop outside air leg (without damper) [Pa]
MassFlowRate	m0Rec_flow		Mass flow rate recirculation air damper [kg/s]
Pressure	dp0Rec		Pressure drop recirculation air leg (without damper) [Pa]
MassFlowRate	m0Exh_flow		Mass flow rate exhaust air damper [kg/s]
Pressure	dp0Exh		Pressure drop exhaust air leg (without damper) [Pa]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Connectors

Type Name Description

FluidPort_a port_Out Fluid connector a (positive design flow direction is from port_a to port_b)

FluidPort_a port_OutMin Fluid connector a (positive design flow direction is from port_a to port_b)

FluidPort_b port_Exh Fluid connector b (positive design flow direction is from port_a to port_b)

FluidPort_a port_Ret Fluid connector a (positive design flow direction is from port_a to port_b)

FluidPort_b port_Sup Fluid connector b (positive design flow direction is from port_a to port_b)

input RealInput y Damper position (0: closed, 1: open)

input RealInput yOutMin Damper position minimum outside air (0: closed, 1: open)

Type	Name	Description
FluidPort_a	port_Out	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_a	port_OutMin	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_Exh	Fluid connector b (positive design flow direction is from port_a to port_b)
FluidPort_a	port_Ret	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_Sup	Fluid connector b (positive design flow direction is from port_a to port_b)
input RealInput	y	Damper position (0: closed, 1: open)
input RealInput	yOutMin	Damper position minimum outside air (0: closed, 1: open)

Modelica definition

model OAMixingBoxMinimumDamper 
  "Outside air mixing box with parallel damper for minimum outside air flow rate"
  extends Buildings.BaseClasses.BaseIcon;
  outer Modelica_Fluid.System system "System wide properties";
  replaceable package Medium = 
      Modelica.Media.Interfaces.PartialMedium "Medium in the component";
   import Modelica.Constants;

  parameter Boolean allowFlowReversal = system.allowFlowReversal 
    "= true to allow flow reversal, false restricts to design direction (port_a -> port_b)";

  Buildings.Fluids.Actuators.Dampers.Exponential damOAMin(
                                                         A=AOutMin,
    redeclare package Medium = Medium,
    m0_flow=m0OutMin_flow) "Damper for minimum outside air supply";
  Buildings.Fluids.Actuators.Dampers.Exponential damOA(
                                                      A=AOut,
    redeclare package Medium = Medium,
    m0_flow=m0Out_flow);
  parameter Modelica.SIunits.Area AOutMin 
    "Face area minimum outside air damper";
  parameter Modelica.SIunits.Area AOut "Face area outside air damper";
  Buildings.Fluids.Actuators.Dampers.Exponential damExh(
                                                       A=AExh,
    redeclare package Medium = Medium,
    m0_flow=m0Exh_flow) "Exhaust air damper";
  parameter Modelica.SIunits.Area AExh "Face area exhaust air damper";
  Buildings.Fluids.Actuators.Dampers.Exponential damRec(
                                                       A=ARec,
    redeclare package Medium = Medium,
    m0_flow=m0Rec_flow) "Recirculation air damper";
  parameter Modelica.SIunits.Area ARec "Face area recirculation air damper";

  parameter Modelica.SIunits.MassFlowRate m0OutMin_flow 
    "Mass flow rate minimum outside air damper";
  parameter Modelica.SIunits.Pressure dp0OutMin 
    "Pressure drop minimum outside air leg (without damper)";

  parameter Modelica.SIunits.MassFlowRate m0Out_flow 
    "Mass flow rate outside air damper";
  parameter Modelica.SIunits.Pressure dp0Out 
    "Pressure drop outside air leg (without damper)";

  parameter Modelica.SIunits.MassFlowRate m0Rec_flow 
    "Mass flow rate recirculation air damper";
  parameter Modelica.SIunits.Pressure dp0Rec 
    "Pressure drop recirculation air leg (without damper)";

  parameter Modelica.SIunits.MassFlowRate m0Exh_flow 
    "Mass flow rate exhaust air damper";
  parameter Modelica.SIunits.Pressure dp0Exh 
    "Pressure drop exhaust air leg (without damper)";

  Buildings.Fluids.FixedResistances.FixedResistanceDpM preDroOutMin(
                                                              m0_flow=
        m0OutMin_flow, dp0=dp0OutMin, redeclare package Medium = Medium) 
    "Pressure drop for minimum outside air branch";
  Buildings.Fluids.FixedResistances.FixedResistanceDpM preDroOut(
                                                           m0_flow=
        m0Out_flow, dp0=dp0Out, redeclare package Medium = Medium) 
    "Pressure drop for outside air branch";
  Buildings.Fluids.FixedResistances.FixedResistanceDpM preDroExh(
                                                           m0_flow=
        m0Exh_flow, dp0=dp0Exh, redeclare package Medium = Medium) 
    "Pressure drop for exhaust air branch";
  Buildings.Fluids.FixedResistances.FixedResistanceDpM preDroRec(
                                                           m0_flow=
        m0Rec_flow, dp0=dp0Rec, redeclare package Medium = Medium) 
    "Pressure drop for recirculation air branch";
  Modelica_Fluid.Interfaces.FluidPort_a port_Out(redeclare package Medium = 
        Medium, m_flow(start=0, min=if allowFlowReversal then -Constants.inf else 
                0)) 
    "Fluid connector a (positive design flow direction is from port_a to port_b)";
  Modelica_Fluid.Interfaces.FluidPort_a port_OutMin(redeclare package Medium = 
        Medium, m_flow(start=0, min=if allowFlowReversal then -Constants.inf else 
                0)) 
    "Fluid connector a (positive design flow direction is from port_a to port_b)";
  Modelica_Fluid.Interfaces.FluidPort_b port_Exh(redeclare package Medium = 
        Medium, m_flow(start=0, max=if allowFlowReversal then +Constants.inf else 
                0)) 
    "Fluid connector b (positive design flow direction is from port_a to port_b)";
  Modelica_Fluid.Interfaces.FluidPort_a port_Ret(redeclare package Medium = 
        Medium, m_flow(start=0, min=if allowFlowReversal then -Constants.inf else 
                0)) 
    "Fluid connector a (positive design flow direction is from port_a to port_b)";
  Modelica_Fluid.Interfaces.FluidPort_b port_Sup(redeclare package Medium = 
        Medium, m_flow(start=0, max=if allowFlowReversal then +Constants.inf else 
                0)) 
    "Fluid connector b (positive design flow direction is from port_a to port_b)";
  Modelica.Blocks.Interfaces.RealInput y "Damper position (0: closed, 1: open)";
  Modelica.Blocks.Interfaces.RealInput yOutMin 
    "Damper position minimum outside air (0: closed, 1: open)";
  Modelica.Blocks.Sources.Constant uni(k=1) "Unity signal";

  Modelica.Blocks.Math.Add add(k2=-1);
protected 
  Modelica_Fluid.Interfaces.FluidPort_b port_Ret1(redeclare package Medium = 
        Medium);
protected 
  Modelica_Fluid.Interfaces.FluidPort_b port_b1(redeclare package Medium = 
        Medium);
equation 
  connect(preDroOutMin.port_b, damOAMin.port_a);
  connect(preDroOut.port_b, damOA.port_a);
  connect(yOutMin, damOAMin.y);
  connect(y, damOA.y);
  connect(y, damExh.y);
  connect(damExh.port_b, preDroExh.port_a);
  connect(preDroExh.port_b, port_Exh);
  connect(preDroOut.port_a, port_Out);
  connect(port_OutMin, preDroOutMin.port_a);
  connect(uni.y, add.u1);
  connect(y, add.u2);
  connect(add.y, damRec.y);
  connect(port_Ret, port_Ret1);
  connect(preDroRec.port_a, port_Ret1);
  connect(damExh.port_a, port_Ret1);
  connect(damOAMin.port_b, port_b1);
  connect(port_Sup, port_b1);
  connect(damRec.port_b, port_b1);
  connect(damOA.port_b, port_b1);
  connect(preDroRec.port_b, damRec.port_a);
end OAMixingBoxMinimumDamper;

Buildings.Fluids.Actuators.Dampers.VAVBoxExponential

VAV box with a fixed resistance plus a damper model withe exponential characteristics

Buildings.Fluids.Actuators.Dampers.VAVBoxExponential

Information

VAV box plus an air damper with a flow coefficient that is an exponential function of the opening angle.

Extends from Buildings.Fluids.Actuators.BaseClasses.PartialDamperExponential (Partial model for air dampers with exponential opening characteristics).

Parameters

Type Name Default Description

replaceable package Medium Modelica.Media.Interfaces.Pa... Medium in the component

Area A Face area [m2]

Boolean roundDuct false Set to true for round duct, false for square cross section

Real ReC 4000 Reynolds number where transition to laminar starts

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

Nominal condition

MassFlowRate m0_flow Nominal mass flow rate [kg/s]

Initialization

Real kDam.start 1 Flow coefficient for damper, k=m_flow/sqrt(dp), with unit=(kg*m)^(1/2)

Nominal Condition

Pressure dp0 Pressure drop, including fully open damper [Pa]

Assumptions

Boolean allowFlowReversal system.allowFlowReversal = true to allow flow reversal, false restricts to design direction (port_a -> port_b)

Advanced

AbsolutePressure dp_start 0.01*system.p_start Guess value of dp = port_a.p - port_b.p [Pa]

MassFlowRate m_flow_start system.m_flow_start Guess value of m_flow = port_a.m_flow [kg/s]

MassFlowRate m_flow_small 1E-4*m0_flow Small mass flow rate for regularization of zero flow [kg/s]

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

Diagnostics

Boolean show_T true = true, if temperatures at port_a and port_b are computed

Boolean show_V_flow true = true, if volume flow rate at inflowing port is computed

Type	Name	Default	Description
replaceable package Medium	Modelica.Media.Interfaces.Pa...	Medium in the component
Area	A		Face area [m2]
Boolean	roundDuct	false	Set to true for round duct, false for square cross section
Real	ReC	4000	Reynolds number where transition to laminar starts
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
Nominal condition
MassFlowRate	m0_flow		Nominal mass flow rate [kg/s]
Initialization
Real	kDam.start	1	Flow coefficient for damper, k=m_flow/sqrt(dp), with unit=(kg*m)^(1/2)
Nominal Condition
Pressure	dp0		Pressure drop, including fully open damper [Pa]
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
AbsolutePressure	dp_start	0.01*system.p_start	Guess value of dp = port_a.p - port_b.p [Pa]
MassFlowRate	m_flow_start	system.m_flow_start	Guess value of m_flow = port_a.m_flow [kg/s]
MassFlowRate	m_flow_small	1E-4*m0_flow	Small mass flow rate for regularization of zero flow [kg/s]
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
Diagnostics
Boolean	show_T	true	= true, if temperatures at port_a and port_b are computed
Boolean	show_V_flow	true	= true, if volume flow rate at inflowing port is computed

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)
input RealInput	y	Damper position (0: closed, 1: open)

Modelica definition

model VAVBoxExponential 
  "VAV box with a fixed resistance plus a damper model withe exponential characteristics"
  extends Buildings.Fluids.Actuators.BaseClasses.PartialDamperExponential;
  import SI = Modelica.SIunits;

  parameter SI.MassFlowRate m0_flow "Mass flow rate";
  parameter SI.Pressure dp0(min=0) "Pressure drop, including fully open damper";
protected 
  parameter SI.Pressure dpDamOpe0 = k1*m0_flow^2/2/Medium.density(sta0)/A^2 
    "Pressure drop of fully open damper at nominal flow rate";
  parameter Real kRes = m0_flow / sqrt(dp0-dpDamOpe0) 
    "Resistance coefficient for fixed resistance element with unit=(kg.m)^(1/2)";
equation 
   kInv = 1/kRes/kRes + 1/kDam/kDam 
    "flow coefficient for resistance base model";
end VAVBoxExponential;

HTML-documentation generated by Dymola Thu Feb 19 16:50:53 2009.

	opposed blades	single blades
yL	15/90	15/90
yU	55/90	65/90
k0	1E6	1E6
k1	0.2 to 0.5	0.2 to 0.5
a	-1.51	-1.51
b	0.105*90	0.0842*90