Buildings.Examples.VAVCO2

Package Content

Name	Description
VAVSystemCTControl	VAV system model of MIT building with continuous time control for static pressure reset
BaseClasses	Package with base classes for example models

Buildings.Examples.VAVCO2.VAVSystemCTControl

Information

This examples demonstrates the implementation of CO₂ control for a variable air volume flow system. Each room has a CO₂ source. Depending on the CO₂ concentrations, the air damper in the room open or close. The supply and return fans are controlled to provide a constant static pressure.

Note that this example does not control the room temperature and the heat flow through the building envelope. It only implements the CO₂ transfer.

Information for Windows users:

This example uses the Radau solver. For Dymola 7.4, Microsoft Visual C++ Express 2010 does not work with the Radau solver. Microsoft Visual C++ Express is not officialy supported by Dymola 7.4 and it can not link the model to the Radau solver. To avoid this problem, use another compiler, such as Visual C++ 2008.

Parameters

Type	Name	Default	Description
MassFlowRate	mMIT_flow	roo.m0Tot_flow	Nominal mass flow rate of MIT system model as in ASHRAE 825-RP [kg/s]
Pressure	dpSuiSup_nominal	95	Pressure drop supply air leg with splitters of one suite (obtained from simulation) [Pa]
Pressure	dpSuiRet_nominal	233	Pressure drop return air leg with splitters of one suite (obtained from simulation) [Pa]
Pressure	dpFanSupMIT_nominal	1050	Pressure increase over supply fan in MIT system model as in ASHRAE 825-RP (obtained from simulation) [Pa]
Pressure	dpFanRetMIT_nominal	347	Pressure increase over supply fan in MIT system model as in ASHRAE 825-RP (obtained from simulation) [Pa]
Real	scaM_flow	1	Scaling factor for mass flow rate
Real	scaDpFanSup_nominal	1	Scaling factor for supply fan pressure lift with NSui number of suites
Real	scaDpFanRet_nominal	1	Scaling factor for supply fan pressure lift with NSui number of suites

Modelica definition

model VAVSystemCTControl 
  "VAV system model of MIT building with continuous time control for static pressure reset"

 package Medium = Buildings.Media.GasesPTDecoupled.SimpleAir(extraPropertiesNames={"CO2"});

 parameter Modelica.SIunits.MassFlowRate mMIT_flow = roo.m0Tot_flow 
    "Nominal mass flow rate of MIT system model as in ASHRAE 825-RP";

parameter Modelica.SIunits.Pressure dpSuiSup_nominal = 95 
    "Pressure drop supply air leg with splitters of one suite (obtained from simulation)";
parameter Modelica.SIunits.Pressure dpSuiRet_nominal = 233 
    "Pressure drop return air leg with splitters of one suite (obtained from simulation)";
parameter Modelica.SIunits.Pressure dpFanSupMIT_nominal = 1050 
    "Pressure increase over supply fan in MIT system model as in ASHRAE 825-RP (obtained from simulation)";
parameter Modelica.SIunits.Pressure dpFanRetMIT_nominal = 347 
    "Pressure increase over supply fan in MIT system model as in ASHRAE 825-RP (obtained from simulation)";

parameter Real scaM_flow = 1 "Scaling factor for mass flow rate";
parameter Real scaDpFanSup_nominal = 1 
    "Scaling factor for supply fan pressure lift with NSui number of suites";
parameter Real scaDpFanRet_nominal = 1 
    "Scaling factor for supply fan pressure lift with NSui number of suites";

  Modelica.Blocks.Sources.Constant PAtm(k=101325);
  Modelica.Blocks.Sources.Constant yDam(k=0.5);
Buildings.Fluid.FixedResistances.FixedResistanceDpM res31(
                                               dp_nominal=0.546,
  m_flow_nominal=scaM_flow*1,
  dh=sqrt(scaM_flow)*1,
  redeclare package Medium = Medium);
Buildings.Fluid.FixedResistances.FixedResistanceDpM res33(
  dp_nominal=0.164,
  dh=sqrt(scaM_flow)*1,
  m_flow_nominal=scaM_flow*1,
  redeclare package Medium = Medium);
Buildings.Fluid.FixedResistances.FixedResistanceDpM res57(
                                               dp_nominal=0.118000,
  m_flow_nominal=scaM_flow*1,
  dh=sqrt(scaM_flow)*1,
  redeclare package Medium = Medium);
Buildings.Examples.VAVCO2.BaseClasses.Suite roo(redeclare package Medium = Medium, scaM_flow=scaM_flow);
Fluid.Actuators.Dampers.MixingBox mixBox(
  dpOut_nominal=0.467,
  dpRec_nominal=0.665,
  AOut=scaM_flow*1.32,
  AExh=scaM_flow*1.05,
  ARec=scaM_flow*1.05,
  mOut_flow_nominal=scaM_flow*1,
  mRec_flow_nominal=scaM_flow*1,
  mExh_flow_nominal=scaM_flow*1,
  redeclare package Medium = Medium,
    dpExh_nominal=0.467) "mixing box";
  Buildings.Fluid.Sources.Boundary_pT bouIn(
    redeclare package Medium = Medium,
    use_p_in=true,
    nPorts=3,
    T=293.15);
  inner Modelica.Fluid.System system;

   Buildings.Controls.Continuous.LimPID PID(
    Ti=60,
    yMax=1,
    yMin=0,
    initType=Modelica.Blocks.Types.InitPID.InitialState,
    y_start=0,
    Td=60,
    controllerType=Modelica.Blocks.Types.SimpleController.P,
    k=0.1);
  Modelica.Blocks.Sources.Constant const(k=120);
  Fluid.Movers.FlowMachine_y fan32(
    redeclare package Medium = Medium,
    m_flow_nominal=mMIT_flow,
    redeclare function flowCharacteristic =
        Buildings.Fluid.Movers.BaseClasses.Characteristics.quadraticFlow (
          V_flow_nominal={0,11.08,14.9}, dp_nominal={1508,743,100}),
    energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyStateInitial,
    dynamicBalance=true);
  Fluid.Movers.FlowMachine_y fan56(
    redeclare package Medium = Medium,
    m_flow_nominal=mMIT_flow,
    redeclare function flowCharacteristic =
        Buildings.Fluid.Movers.BaseClasses.Characteristics.linearFlow (
          V_flow_nominal={2.676,11.05}, dp_nominal={600,100}),
    energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyStateInitial,
    dynamicBalance=true);
equation 
  connect(PAtm.y, bouIn.p_in);
  connect(bouIn.ports[2], mixBox.port_Out);
  connect(bouIn.ports[3], mixBox.port_Exh);
  connect(const.y, PID.u_s);
  connect(roo.p_rel, PID.u_m);
  connect(yDam.y, mixBox.y);
  connect(roo.p, PAtm.y);
  connect(mixBox.port_Sup, res31.port_a);

  connect(res31.port_b, fan32.port_a);
  connect(fan32.port_b, res33.port_a);
  connect(fan56.port_a, roo.port_bExh);
  connect(res57.port_b, mixBox.port_Ret);
  connect(res57.port_a, fan56.port_b);
  connect(res33.port_b, roo.port_aSup);
  connect(PID.y, fan32.y);
  connect(PID.y, fan56.y);
end VAVSystemCTControl;