Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.DualDuctSnapActing
Sequences for dual duct terminal unit with snap acting control
Information
This package contains sequences for dual duct terminal unit with snap acting control. They are created according to Section 5.11 of ASHRAE Guideline 36, May 2020.
Package Content
Name | Description |
---|---|
Controller | Controller for snap-acting controlled dual-duct terminal unit |
Subsequences | Package of subsequences for snap-acting controlled dual-duct terminal unit |
Validation | Collection of validation models |
Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.DualDuctSnapActing.Controller
Controller for snap-acting controlled dual-duct terminal unit
Information
Controller for snap-acting controlled dual-duct terminal unit according to Section 5.11 of ASHRAE
Guideline 36, May 2020. It outputs discharge airflow setpoint VSet_flow
,
cold and hot duct dampers position setpoint (yCooDam
, yHeaDam
),
cooling supply temperature setpoint reset request yZonCooTemResReq
,
heating supply temperature setpoint reset request yZonHeaTemResReq
,
cold-duct static pressure setpoint reset request yColDucPreResReq
,
hot-duct static pressure setpoint reset request yHotDucPreResReq
,
heating fan request yHeaFanReq
.
It also outputs the alarms about the low airflow yLowFloAla
,
leaking dampers, and airflow sensor(s) calibration alarm.
The sequence consists of six subsequences.
a. Heating and cooling control loop
The subsequence is implementd according to Section 5.3.4. The measured zone
temperature TZon
, zone setpoints temperatures THeaSet
and
TCooSet
are inputs to the instance of class
Buildings.Controls.OBC.ASHRAE.G36.ThermalZones.ZoneStates to generate the
heating and cooling control loop signal.
b. Active airflow setpoint calculation
This sequence sets the active maximum airflow according to
Section 5.11.4. Depending on operation modes uOpeMod
, it sets the
airflow rate limits for cooling and heating supply.
See
Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.DualDuctSnapActing.Subsequences.ActiveAirFlow.
c. Dampers control
This sequence sets the dampers position setpoints.
The implementation is according to Section 5.11.5. The sequence outputs
discharge airflow rate setpoint VSet_flow
, cold and hot ducts damper
position setpoints (yCooDam
, yHeaDam
). It has two
sequences depending on if the unit has the dual inlet flow sensor.
- The unit has dual inlet flow sensor. See Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.DualDuctSnapActing.Subsequences.DampersDualSensors.
- The unit has single discharge flow sensor. See Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.DualDuctSnapActing.Subsequences.DampersSingleSensors.
d. System reset requests generation
According to Section 5.11.8, this sequence outputs the system reset requests, i.e.
cooling and heating supply air temperature reset requests (yZonCooTemResReq
and
yZonHeaTemResReq
),
cold and hot duct static pressure reset requests (yColDucPreResReq
and
yHotDucPreResReq
), and the heating fan requests
yHeaFanReq
.
See
Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.DualDuctSnapActing.Subsequences.SystemRequests.
e. Alarms
According to Section 5.11.6, this sequence outputs the alarms of low discharge flow, leaking dampers and airflow sensor calibration alarm. See Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.DualDuctSnapActing.Subsequences.Alarms.
f. Testing and commissioning overrides
According to Section 5.11.7, this sequence allows the override the aiflow and dampers position setpoints. See Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.DualDuctSnapActing.Subsequences.Overrides.
Parameters
Type | Name | Default | Description |
---|---|---|---|
VentilationStandard | venStd | Ventilation standard, ASHRAE 62.1 or Title 24 | |
Boolean | have_winSen | true | True: the zone has window sensor |
Boolean | have_occSen | true | True: the zone has occupancy sensor |
Boolean | have_CO2Sen | true | True: the zone has CO2 sensor |
Boolean | have_duaSen | True: the unit has dual inlet flow sensor | |
Boolean | permit_occStandby | true | True: occupied-standby mode is permitted |
Real | VOccMin_flow | Zone minimum outdoor airflow for occupants [m3/s] | |
Real | VAreMin_flow | Zone minimum outdoor airflow for building area [m3/s] | |
Design conditions | |||
Real | VAreBreZon_flow | Design area component of the breathing zone outdoor airflow [m3/s] | |
Real | VPopBreZon_flow | Design population component of the breathing zone outdoor airflow [m3/s] | |
Real | VMin_flow | Design zone minimum airflow setpoint [m3/s] | |
Real | VCooMax_flow | Design zone cooling maximum airflow rate [m3/s] | |
Real | VHeaMax_flow | Design zone heating maximum airflow rate [m3/s] | |
Control loops | |||
Cooling | |||
Real | kCooCon | 0.1 | Gain of controller for cooling control loop |
Real | TiCooCon | 900 | Time constant of integrator block for cooling control loop [s] |
Heating | |||
Real | kHeaCon | 0.1 | Gain of controller for heating control loop |
Real | TiHeaCon | 900 | Time constant of integrator block for heating control loop [s] |
Dampers | |||
SimpleController | controllerTypeDam | Buildings.Controls.OBC.CDL.T... | Type of controller |
Real | kDam | 0.5 | Gain of controller for damper control |
Real | TiDam | 300 | Time constant of integrator block for damper control [s] |
Real | TdDam | 0.1 | Time constant of derivative block for damper control [s] |
System requests | |||
Real | thrTemDif | 3 | Threshold difference between zone temperature and cooling setpoint for generating 3 cooling SAT reset requests [K] |
Real | twoTemDif | 2 | Threshold difference between zone temperature and cooling setpoint for generating 2 cooling SAT reset requests [K] |
Duration time | |||
Real | durTimTem | 120 | Duration time of zone temperature exceeds setpoint [s] |
Real | durTimFlo | 60 | Duration time of airflow rate less than setpoint [s] |
Alarms | |||
Real | staPreMul | 1 | Importance multiplier for the zone static pressure reset control loop |
Real | lowFloTim | 300 | Threshold time to check low flow rate [s] |
Real | lowTemTim | 600 | Threshold time to check low discharge temperature [s] |
Real | fanOffTim | 600 | Threshold time to check fan off [s] |
Real | leaFloTim | 600 | Threshold time to check damper leaking airflow [s] |
Real | valCloTim | 900 | Threshold time to check valve leaking water flow [s] |
Time-based suppresion | |||
Real | chaRat | 540 | Gain factor to calculate suppression time based on the change of the setpoint, second per degC |
Real | maxSupTim | 1800 | Maximum suppression time [s] |
Advanced | |||
Real | dTHys | 0.25 | Near zero temperature difference, below which the difference will be seen as zero [K] |
Real | looHys | 0.01 | Loop output hysteresis below which the output will be seen as zero [1] |
Real | floHys | 0.01*VMin_flow | Near zero flow rate, below which the flow rate or difference will be seen as zero [m3/s] |
Real | damPosHys | 0.005 | Near zero damper position, below which the damper will be seen as closed [1] |
Real | staTim | 1800 | Delay triggering alarms after enabling AHU supply fan [s] |
Real | iniDam | 0.01 | Initial damper position when the damper control is enabled [1] |
Real | iniCooDam | 0.01 | Initial cooling damper position when the damper control is enabled [1] |
Real | iniHeaDam | 0.01 | Initial heating damper position when the damper control is enabled [1] |
Control loops | |||
Real | timChe | 30 | Threshold time to check the zone temperature status [s] |
Distribution effectiveness | |||
Real | zonDisEff_cool | 1.0 | Zone cooling air distribution effectiveness [1] |
Real | zonDisEff_heat | 0.8 | Zone heating air distribution effectiveness [1] |
Time-based suppresion | |||
Real | samplePeriod | 120 | Sample period of component, set to the same value as the trim and respond that process static pressure reset [s] |
Connectors
Type | Name | Description |
---|---|---|
input RealInput | TZon | Measured room temperature [K] |
input RealInput | TCooSet | Setpoint temperature for room for cooling [K] |
input RealInput | THeaSet | Setpoint temperature for room for heating [K] |
input BooleanInput | u1Win | Window status, normally closed (true), when windows open, it becomes false |
input BooleanInput | u1Occ | True: the zone is populated |
input IntegerInput | uOpeMod | Zone operation mode |
input RealInput | ppmCO2Set | CO2 concentration setpoint |
input RealInput | ppmCO2 | Detected CO2 concentration |
input RealInput | TDis | Measured discharge air temperature [K] |
input RealInput | TColSup | Cold duct supply air temperature from central air handler [K] |
input RealInput | VColDucDis_flow | Measured cold-duct discharge airflow rate airflow rate [m3/s] |
input BooleanInput | u1CooAHU | Cooling air handler status |
input RealInput | THotSup | Hot duct supply air temperature from central air handler [K] |
input RealInput | VHotDucDis_flow | Measured hot-duct discharge airflow rate airflow rate [m3/s] |
input BooleanInput | u1HeaAHU | Heating air handler status |
input RealInput | VDis_flow | Measured discharge airflow rate airflow rate [m3/s] |
input IntegerInput | oveFloSet | Index of overriding flow setpoint, 1: set to zero; 2: set to cooling maximum; 3: set to minimum flow; 4: set to heating maximum |
input IntegerInput | oveCooDamPos | Index of overriding cooling damper position, 1: set to close; 2: set to open |
input IntegerInput | oveHeaDamPos | Index of overriding heating damper position, 1: set to close; 2: set to open |
output RealOutput | VSet_flow | Airflow setpoint after considering override [m3/s] |
output RealOutput | yCooDam | Cooling damper commanded position, or commanded flow rate ratio [1] |
output RealOutput | yHeaDam | Heating damper commanded position, or commanded flow rate ratio [1] |
output RealOutput | VAdjPopBreZon_flow | Adjusted population component breathing zone flow rate [m3/s] |
output RealOutput | VAdjAreBreZon_flow | Adjusted area component breathing zone flow rate [m3/s] |
output RealOutput | VMinOA_flow | Minimum outdoor airflow setpoint [m3/s] |
output RealOutput | VZonAbsMin_flow | Zone absolute minimum outdoor airflow setpoint [m3/s] |
output RealOutput | VZonDesMin_flow | Zone design minimum outdoor airflow setpoint [m3/s] |
output RealOutput | yCO2 | CO2 control loop signal [1] |
output IntegerOutput | yZonCooTemResReq | Zone cooling supply air temperature reset request |
output IntegerOutput | yColDucPreResReq | Cold duct pressure reset requests |
output IntegerOutput | yZonHeaTemResReq | Zone heating supply air temperature reset request |
output IntegerOutput | yHotDucPreResReq | Hot duct pressure reset requests |
output IntegerOutput | yHeaFanReq | Heating fan request |
output IntegerOutput | yLowFloAla | Low airflow alarms |
output IntegerOutput | yFloSenAla | Airflow sensor calibration alarm |
output IntegerOutput | yLeaDamAla | Leaking dampers alarm, could be heating or cooling damper |
output IntegerOutput | yColFloSenAla | Cold-duct airflow sensor calibration alarm |
output IntegerOutput | yColLeaDamAla | Leaking cold-duct damper alarm |
output IntegerOutput | yHotFloSenAla | Hot-duct airflow sensor calibration alarm |
output IntegerOutput | yHotLeaDamAla | Leaking hot-duct damper alarm |