Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers
Package of sequences for cooling tower control
Information
This package contains sequences for cooling tower control. The implementation is based on section 5.20.12 in ASHRAE Guideline 36-2021.
Package Content
| Name | Description |
|---|---|
 Controller
|
Cooling tower controller |
 WaterLevel
|
Sequences to control water level in cooling tower |
 FanSpeed
|
Package of sequences for cooling tower fan speed control |
| Staging
|
Package of sequences for cooling tower staging |
 Validation
|
Collection of validation models |
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.Controller
Cooling tower controller
Information
Block that controls the cooling tower cells enabling status yTowSta,
the supply isolation valve positions yIsoVal of each cell and the
cell fan operating speed ySpeSet.
This is implemented according to ASHRAE Guideline 36-2021, section 5.20.12.
The section specifies sequences to control the cooling tower.
It includes three subsequences:
- Sequence of controlling tower fan speed, see Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.FanSpeed.Controller for a description. Note that in current implementation, the fan speed is controlled to maintain the condenser water return temperature at the setpoint.
- Sequence of cooling tower staging, see Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.Staging.Controller for a description. Note that the sequence assumes that the cells are enabled in order as it is labelled, meaning that it enables the cells as cell 1, 2, 3, etc.
- Sequence of tower make-up water valve control, see Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.WaterLevel for a description.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| HeadPressureControl | chiHeaPreCon | Buildings.Controls.OBC.ASHRA... | Chiller head pressure controlled type |
| Integer | nChi | 2 | Total number of chillers |
| Integer | nPlaSta | 5 | Total number of plant stages, including stage zero and the stages with a WSE, if applicable |
| Integer | nTowCel | 2 | Total number of cooling tower cells |
| Integer | nConWatPum | 2 | Total number of condenser water pumps |
| TowerSpeedControl | fanSpeCon | Buildings.Controls.OBC.ASHRA... | Tower fan speed control type |
| Boolean | closeCoupledPlant | false | True: the plant is close coupled, i.e. the pipe length from the chillers to cooling towers does not exceed approximately 100 feet |
| Boolean | have_WSE | true | Flag to indicate if the plant has waterside economizer |
| Nominal | |||
| Real | desCap | 1e6 | Plant design capacity [W] |
| Real | fanSpeMin | 0.1 | Minimum tower fan speed |
| Fan speed | |||
| WSE enabled | |||
| Real | chiMinCap[nChi] | {1e4,1e4} | Minimum cyclining load below which chiller will begin cycling [W] |
| SimpleController | intOpeCon | Buildings.Controls.OBC.CDL.T... | Controller in the mode when WSE and chillers are enabled |
| Real | kIntOpe | 1 | Gain of controller |
| Real | TiIntOpe | 0.5 | Time constant of integrator block [s] |
| Real | TdIntOpe | 0.1 | Time constant of derivative block [s] |
| SimpleController | chiWatCon | Buildings.Controls.OBC.CDL.T... | Controller in the mode when only WSE is enabled |
| Real | kWSE | 1 | Gain of controller |
| Real | TiWSE | 0.5 | Time constant of integrator block [s] |
| Real | TdWSE | 0.1 | Time constant of derivative block [s] |
| Return temperature control | |||
| Real | minChiLif[nChi] | {12,12} | Minimum LIFT of each chiller [K] |
| Real | TConWatSup_nominal[nChi] | {293.15,293.15} | Condenser water supply temperature (condenser entering) of each chiller [K] |
| Real | TConWatRet_nominal[nChi] | {303.15,303.15} | Condenser water return temperature (condenser leaving) of each chiller [K] |
| Real | TChiWatSupMin[nChi] | {278.15,278.15} | Lowest chilled water supply temperature oc each chiller [K] |
| SimpleController | couPlaCon | Buildings.Controls.OBC.CDL.T... | Type of coupled plant controller |
| Real | kCouPla | 1 | Gain of controller |
| Real | TiCouPla | 0.5 | Time constant of integrator block [s] |
| Real | TdCouPla | 0.1 | Time constant of derivative block [s] |
| Real | yCouPlaMax | 1 | Upper limit of output |
| Real | yCouPlaMin | 0 | Lower limit of output |
| Real | samplePeriod | 30 | Period of sampling condenser water supply and return temperature difference [s] |
| SimpleController | supWatCon | Buildings.Controls.OBC.CDL.T... | Condenser supply water temperature controller for less coupled plant |
| Real | kSupCon | 1 | Gain of controller |
| Real | TiSupCon | 0.5 | Time constant of integrator block [s] |
| Real | TdSupCon | 0.1 | Time constant of derivative block [s] |
| Real | ySupConMax | 1 | Upper limit of output |
| Real | ySupConMin | 0 | Lower limit of output |
| Advanced | |||
| Real | speChe | 0.005 | Lower threshold value to check fan or pump speed |
| Real | iniPlaTim | 600 | Time to hold return temperature at initial setpoint after plant being enabled [s] |
| Real | ramTim | 180 | Time to ramp return water temperature from initial value to setpoint [s] |
| Real | cheMinFanSpe | 300 | Threshold time for checking duration when tower fan equals to the minimum tower fan speed [s] |
| Real | cheMaxTowSpe | 300 | Threshold time for checking duration when any enabled chiller maximum cooling speed equals to the minimum tower fan speed [s] |
| Real | cheTowOff | 60 | Threshold time for checking duration when there is no enabled tower fan [s] |
| Tower staging | |||
| Nominal | |||
| Real | staVec[nPlaSta] | {0,0.5,1,1.5,2} | Plant stage vector, element value like x.5 means chiller stage x plus WSE |
| Integer | towCelOnSet[nPlaSta] | {0,1,1,2,2} | Design number of tower fan cells that should be enabled, according to current chiller stage and WSE status |
| Isolation valves | |||
| Boolean | have_inlIsoVal | true | True: tower cells have the inlet isolation valve |
| Boolean | have_outIsoVal | false | True: tower cells have the outlet isolation valve |
| Boolean | have_endSwi | false | True: tower cells isolatiove valve have the end switch feedback |
| Real | chaTowCelIsoTim | 90 | Nominal time needed for open isolation valve of the tower cells |
| Makeup water | |||
| Real | watLevMin | 0.7 | Minimum cooling tower water level recommended by manufacturer [m] |
| Real | watLevMax | 1 | Maximum cooling tower water level recommended by manufacturer [m] |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | uChiLoa | Current cooling load [W] |
| input BooleanInput | uChi[nChi] | Vector of chiller proven on status: true=ON |
| input BooleanInput | uWse | Waterside economizer proven on status: true=ON |
| input RealInput | TChiWatSup | Chilled water supply temperature [K] |
| input RealInput | TChiWatSupSet | Chilled water supply temperature setpoint [K] |
| input RealInput | reqPlaCap | Current required plant capacity [W] |
| input RealInput | uMaxSpeSet[nChi] | Maximum cooling tower speed setpoint from each chiller head pressure control loop [1] |
| input BooleanInput | uTowSta[nTowCel] | Vector of tower cell proven on status: true=running tower cell |
| input BooleanInput | uPla | Plant enabling status |
| input RealInput | TConWatRet | Condenser water return temperature (condenser leaving) [K] |
| input BooleanInput | uConWatPum[nConWatPum] | Current condenser water pump status |
| input RealInput | TConWatSup | Condenser water supply temperature (condenser entering) [K] |
| input BooleanInput | uEnaPla | True: plant is just enabled |
| input IntegerInput | uChiSta | Current chiller stage |
| input IntegerInput | uChiStaSet | Chiller stage setpoint |
| input BooleanInput | uTowStaCha | Cooling tower stage change command from plant staging process |
| input BooleanInput | u1InlIsoValOpe[nTowCel] | Tower cells inlet isolation valve open end switch. True: the isolation valve is fully open |
| input BooleanInput | u1OutIsoValOpe[nTowCel] | Tower cells outlet isolation valve open end switch. True: the isolation valve is fully open |
| input BooleanInput | u1InlIsoValClo[nTowCel] | Tower cells inlet isolation valve close end switch. True: the isolation valve is fully closed |
| input BooleanInput | u1OutIsoValClo[nTowCel] | Tower cells outlet isolation valve close end switch. True: the isolation valve is fully closed |
| input RealInput | watLev | Measured water level [m] |
| output RealOutput | yLifMax | Maximum LIFT among enabled chillers [K] |
| output RealOutput | yLifMin | Minimum LIFT among enabled chillers [K] |
| output RealOutput | TConWatRetSet | Condenser water return temperature setpoint [K] |
| output RealOutput | TConWatSupSet | Condenser water supply temperature setpoint [K] |
| output BooleanOutput | yLeaCel | Lead tower cell status setpoint |
| output BooleanOutput | y1IsoVal[nTowCel] | Cooling tower cells isolation valve position |
| output BooleanOutput | yTowSta[nTowCel] | Vector of tower cells status setpoint |
| output RealOutput | ySpeSet | Fan speed setpoint for enabled cell [1] |
| output BooleanOutput | yMakUp | Makeup water valve On-Off status |
Modelica definition
block Controller "Cooling tower controller"
parameter Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Types.HeadPressureControl
chiHeaPreCon=
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Types.HeadPressureControl.ByPlant
"Chiller head pressure controlled type";
parameter Integer nChi=2 "Total number of chillers";
parameter Integer nPlaSta=5
"Total number of plant stages, including stage zero and the stages with a WSE, if applicable";
parameter Integer nTowCel=2 "Total number of cooling tower cells";
parameter Integer nConWatPum=2 "Total number of condenser water pumps";
parameter Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Types.TowerSpeedControl
fanSpeCon=
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Types.TowerSpeedControl.CondenserWaterReturnTemperaure
"Tower fan speed control type";
final parameter Boolean have_conWatRetCon = fanSpeCon==Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Types.TowerSpeedControl.CondenserWaterReturnTemperaure
"True: the fan speed is controlled to maintain the condenser water return temperature setpoint";
parameter Boolean closeCoupledPlant=false
"True: the plant is close coupled, i.e. the pipe length from the chillers to cooling towers does not exceed approximately 100 feet";
parameter Boolean have_WSE=true
"Flag to indicate if the plant has waterside economizer";
parameter Real desCap(unit="W")=1e6 "Plant design capacity";
parameter Real fanSpeMin=0.1 "Minimum tower fan speed";
// Fan speed control: when WSE is enabled
parameter Real chiMinCap[nChi](unit=fill("W", nChi))={1e4,1e4}
"Minimum cyclining load below which chiller will begin cycling";
parameter Buildings.Controls.OBC.CDL.Types.SimpleController intOpeCon=
Buildings.Controls.OBC.CDL.Types.SimpleController.PI
"Controller in the mode when WSE and chillers are enabled";
parameter Real kIntOpe=1 "Gain of controller";
parameter Real TiIntOpe(unit="s")=0.5
"Time constant of integrator block";
parameter Real TdIntOpe(unit="s")=0.1
"Time constant of derivative block";
parameter Buildings.Controls.OBC.CDL.Types.SimpleController chiWatCon=
Buildings.Controls.OBC.CDL.Types.SimpleController.PI
"Controller in the mode when only WSE is enabled";
parameter Real kWSE=1 "Gain of controller";
parameter Real TiWSE(unit="s")=0.5
"Time constant of integrator block";
parameter Real TdWSE(unit="s")=0.1
"Time constant of derivative block";
// Fan speed control: controlling condenser return water temperature when WSE is not enabled
parameter Real minChiLif[nChi](unit=fill("K", nChi))={12,12}
"Minimum LIFT of each chiller";
parameter Real TConWatSup_nominal[nChi](
unit=fill("K", nChi),
each displayUnit="degC")={293.15,293.15}
"Condenser water supply temperature (condenser entering) of each chiller";
parameter Real TConWatRet_nominal[nChi](
unit=fill("K", nChi),
each displayUnit="degC")={303.15,303.15}
"Condenser water return temperature (condenser leaving) of each chiller";
parameter Real TChiWatSupMin[nChi](
unit=fill("K", nChi),
each displayUnit="degC")={278.15,278.15}
"Lowest chilled water supply temperature oc each chiller";
parameter Buildings.Controls.OBC.CDL.Types.SimpleController couPlaCon=
Buildings.Controls.OBC.CDL.Types.SimpleController.PI
"Type of coupled plant controller";
parameter Real kCouPla=1 "Gain of controller";
parameter Real TiCouPla(unit="s")=0.5
"Time constant of integrator block";
parameter Real TdCouPla(unit="s")=0.1
"Time constant of derivative block";
parameter Real yCouPlaMax=1 "Upper limit of output";
parameter Real yCouPlaMin=0 "Lower limit of output";
parameter Real samplePeriod(unit="s")=30
"Period of sampling condenser water supply and return temperature difference";
parameter Buildings.Controls.OBC.CDL.Types.SimpleController supWatCon=
Buildings.Controls.OBC.CDL.Types.SimpleController.PI
"Condenser supply water temperature controller for less coupled plant";
parameter Real kSupCon=1 "Gain of controller";
parameter Real TiSupCon(unit="s")=0.5
"Time constant of integrator block";
parameter Real TdSupCon(unit="s")=0.1
"Time constant of derivative block";
parameter Real ySupConMax=1 "Upper limit of output";
parameter Real ySupConMin=0 "Lower limit of output";
parameter Real speChe=0.005
"Lower threshold value to check fan or pump speed";
parameter Real iniPlaTim(unit="s")=600
"Time to hold return temperature at initial setpoint after plant being enabled";
parameter Real ramTim(unit="s")=180
"Time to ramp return water temperature from initial value to setpoint";
parameter Real cheMinFanSpe(unit="s")=300
"Threshold time for checking duration when tower fan equals to the minimum tower fan speed";
parameter Real cheMaxTowSpe(unit="s")=300
"Threshold time for checking duration when any enabled chiller maximum cooling speed equals to the minimum tower fan speed";
parameter Real cheTowOff(unit="s")=60
"Threshold time for checking duration when there is no enabled tower fan";
// Tower staging
parameter Real staVec[nPlaSta]={0,0.5,1,1.5,2}
"Plant stage vector, element value like x.5 means chiller stage x plus WSE";
parameter Integer towCelOnSet[nPlaSta]={0,1,1,2,2}
"Design number of tower fan cells that should be enabled, according to current chiller stage and WSE status";
parameter Boolean have_inlIsoVal=true
"True: tower cells have the inlet isolation valve";
parameter Boolean have_outIsoVal=false
"True: tower cells have the outlet isolation valve";
parameter Boolean have_endSwi=false
"True: tower cells isolatiove valve have the end switch feedback";
parameter Real chaTowCelIsoTim=90
"Nominal time needed for open isolation valve of the tower cells";
// Water level control
parameter Real watLevMin(
min=0,
unit="m")=0.7
"Minimum cooling tower water level recommended by manufacturer";
parameter Real watLevMax(unit="m")=1
"Maximum cooling tower water level recommended by manufacturer";
Buildings.Controls.OBC.CDL.Interfaces.RealInput uChiLoa(
final unit="W",
final quantity="HeatFlowRate") if have_WSE "Current cooling load";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uChi[nChi]
"Vector of chiller proven on status: true=ON";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uWse if have_WSE
"Waterside economizer proven on status: true=ON";
Buildings.Controls.OBC.CDL.Interfaces.RealInput TChiWatSup(
final unit="K",
displayUnit="degC",
final quantity="ThermodynamicTemperature") if have_WSE
"Chilled water supply temperature";
Buildings.Controls.OBC.CDL.Interfaces.RealInput TChiWatSupSet(
final unit="K",
displayUnit="degC",
final quantity="ThermodynamicTemperature")
"Chilled water supply temperature setpoint";
Buildings.Controls.OBC.CDL.Interfaces.RealInput reqPlaCap(
final unit="W",
final quantity="HeatFlowRate") "Current required plant capacity";
Buildings.Controls.OBC.CDL.Interfaces.RealInput uMaxSpeSet[nChi](
final min=fill(0, nChi),
final max=fill(1, nChi),
final unit=fill("1", nChi)) if need_heaPreCon
"Maximum cooling tower speed setpoint from each chiller head pressure control loop";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uTowSta[nTowCel]
"Vector of tower cell proven on status: true=running tower cell";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uPla
"Plant enabling status";
Buildings.Controls.OBC.CDL.Interfaces.RealInput TConWatRet(
final unit="K",
displayUnit="degC",
final quantity="ThermodynamicTemperature") if have_conWatRetCon
"Condenser water return temperature (condenser leaving)";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uConWatPum[nConWatPum]
"Current condenser water pump status";
Buildings.Controls.OBC.CDL.Interfaces.RealInput TConWatSup(
final unit="K",
displayUnit="degC",
final quantity="ThermodynamicTemperature") if not closeCoupledPlant
"Condenser water supply temperature (condenser entering)";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uEnaPla
"True: plant is just enabled";
Buildings.Controls.OBC.CDL.Interfaces.IntegerInput uChiSta
"Current chiller stage";
Buildings.Controls.OBC.CDL.Interfaces.IntegerInput uChiStaSet
"Chiller stage setpoint";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput uTowStaCha
"Cooling tower stage change command from plant staging process";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1InlIsoValOpe[nTowCel]
if have_inlIsoVal and have_endSwi
"Tower cells inlet isolation valve open end switch. True: the isolation valve is fully open";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1OutIsoValOpe[nTowCel]
if have_endSwi and have_outIsoVal
"Tower cells outlet isolation valve open end switch. True: the isolation valve is fully open";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1InlIsoValClo[nTowCel]
if have_inlIsoVal and have_endSwi
"Tower cells inlet isolation valve close end switch. True: the isolation valve is fully closed";
Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1OutIsoValClo[nTowCel]
if have_endSwi and have_outIsoVal
"Tower cells outlet isolation valve close end switch. True: the isolation valve is fully closed";
Buildings.Controls.OBC.CDL.Interfaces.RealInput watLev(
final unit="m")
"Measured water level";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput yLifMax(
final unit="K") if have_conWatRetCon
"Maximum LIFT among enabled chillers";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput yLifMin(
final unit="K") if have_conWatRetCon
"Minimum LIFT among enabled chillers";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput TConWatRetSet(
final quantity="ThermodynamicTemperature",
displayUnit="degC",
final unit="K") if have_conWatRetCon
"Condenser water return temperature setpoint";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput TConWatSupSet(
final quantity="ThermodynamicTemperature",
displayUnit="degC",
final unit="K") if have_conWatRetCon and not closeCoupledPlant
"Condenser water supply temperature setpoint";
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput yLeaCel
"Lead tower cell status setpoint";
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput y1IsoVal[nTowCel]
if have_inlIsoVal
"Cooling tower cells isolation valve position";
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput yTowSta[nTowCel]
"Vector of tower cells status setpoint";
Buildings.Controls.OBC.CDL.Interfaces.RealOutput ySpeSet(
final min=0,
final max=1,
final unit="1") if have_conWatRetCon "Fan speed setpoint for enabled cell";
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput yMakUp
"Makeup water valve On-Off status";
protected
parameter Boolean need_heaPreCon = not chiHeaPreCon == Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Types.HeadPressureControl.NotRequired
"True: the plant requires chiller head pressure being controlled";
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.FanSpeed.Controller towFanSpe(
final need_heaPreCon=need_heaPreCon,
final nChi=nChi,
final nTowCel=nTowCel,
final nConWatPum=nConWatPum,
final fanSpeCon=fanSpeCon,
final closeCoupledPlant=closeCoupledPlant,
final have_WSE=have_WSE,
final desCap=desCap,
final fanSpeMin=fanSpeMin,
final chiMinCap=chiMinCap,
final intOpeCon=intOpeCon,
final kIntOpe=kIntOpe,
final TiIntOpe=TiIntOpe,
final TdIntOpe=TdIntOpe,
final chiWatCon=chiWatCon,
final kWSE=kWSE,
final TiWSE=TiWSE,
final TdWSE=TdWSE,
final minChiLif=minChiLif,
final TConWatSup_nominal=TConWatSup_nominal,
final samplePeriod=samplePeriod,
final cheMinFanSpe=cheMinFanSpe,
final cheMaxTowSpe=cheMaxTowSpe,
final cheTowOff=cheTowOff,
final iniPlaTim=iniPlaTim,
final ramTim=ramTim,
final TConWatRet_nominal=TConWatRet_nominal,
final TChiWatSupMin=TChiWatSupMin,
final couPlaCon=couPlaCon,
final kCouPla=kCouPla,
final TiCouPla=TiCouPla,
final TdCouPla=TdCouPla,
final yCouPlaMax=yCouPlaMax,
final yCouPlaMin=yCouPlaMin,
final supWatCon=supWatCon,
final kSupCon=kSupCon,
final TiSupCon=TiSupCon,
final TdSupCon=TdSupCon,
final ySupConMax=ySupConMax,
final ySupConMin=ySupConMin,
final speChe=speChe) "Tower fan speed";
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.Staging.Controller towSta(
final have_WSE=have_WSE,
final nTowCel=nTowCel,
final nConWatPum=nConWatPum,
final nPlaSta=nPlaSta,
final staVec=staVec,
final towCelOnSet=towCelOnSet,
final have_inlIsoVal=have_inlIsoVal,
final have_outIsoVal=have_outIsoVal,
final have_endSwi=have_endSwi,
final chaTowCelIsoTim=chaTowCelIsoTim)
"Cooling tower staging";
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.WaterLevel makUpWat(
final watLevMin=watLevMin,
final watLevMax=watLevMax)
"Make up water control";
Buildings.Controls.OBC.CDL.Reals.Switch swi if have_conWatRetCon
"Logical switch";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant zer(final k=0)
"Zero constant";
Buildings.Controls.OBC.CDL.Logical.MultiOr mulOr(
final nin=nTowCel)
"Check if there is any enabled cell";
Buildings.Controls.OBC.CDL.Logical.MultiOr mulOr1(final nin=nConWatPum)
"Check if there is any pump on";
equation
connect(towSta.yTowSta, yTowSta);
connect(zer.y, swi.u3);
connect(towFanSpe.uChiLoa, uChiLoa);
connect(towFanSpe.uChi, uChi);
connect(towFanSpe.uWse, uWse);
connect(towFanSpe.TChiWatSup, TChiWatSup);
connect(towFanSpe.TChiWatSupSet, TChiWatSupSet);
connect(towFanSpe.reqPlaCap, reqPlaCap);
connect(towFanSpe.uMaxSpeSet, uMaxSpeSet);
connect(towFanSpe.uTow, uTowSta);
connect(towFanSpe.uPla, uPla);
connect(towFanSpe.TConWatRet, TConWatRet);
connect(towFanSpe.TConWatSup, TConWatSup);
connect(towSta.uChiSta, uChiSta);
connect(makUpWat.watLev, watLev);
connect(makUpWat.yMakUp, yMakUp);
connect(uTowSta, towSta.uTowSta);
connect(towSta.uChiStaSet, uChiStaSet);
connect(towSta.uTowStaCha, uTowStaCha);
connect(uWse, towSta.uWse);
connect(towSta.yLeaCel, yLeaCel);
connect(uEnaPla, towSta.uEnaPla);
connect(swi.y, ySpeSet);
connect(uPla, towSta.uPla);
connect(towFanSpe.yLifMax, yLifMax);
connect(towFanSpe.yLifMin, yLifMin);
connect(towFanSpe.ySpeSet, swi.u1);
connect(mulOr.y, swi.u2);
connect(towSta.yTowSta, mulOr.u);
connect(towFanSpe.TConWatRetSet, TConWatRetSet);
connect(towFanSpe.TConWatSupSet, TConWatSupSet);
connect(uConWatPum, towFanSpe.uConWatPum);
connect(uConWatPum, mulOr1.u);
connect(mulOr1.y, towSta.uAnyConWatPum);
connect(towSta.y1IsoVal, y1IsoVal);
connect(u1InlIsoValOpe, towSta.u1InlIsoValOpe);
connect(u1OutIsoValOpe, towSta.u1OutIsoValOpe);
connect(u1InlIsoValClo, towSta.u1InlIsoValClo);
connect(u1OutIsoValClo, towSta.u1OutIsoValClo);
end Controller;
Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.WaterLevel
Sequences to control water level in cooling tower
Information
Block that outputs yMakUp to control the cooling tower make-up water
valve. It is implemented according to ASHRAE Guideline 36-2021,
section 5.20.13, tower make-up water.
Make-up water valve shall cycle based on tower water fill level sensor. The
valve shall open when the water level watLev falls below the minimum
fill level watLevMin recommended by the tower manufacturer. It
shall close when the water level goes above the maximum level watLevMax.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | watLevMin | Minimum cooling tower water level recommended by manufacturer | |
| Real | watLevMax | Maximum cooling tower water level recommended by manufacturer |
Connectors
| Type | Name | Description |
|---|---|---|
| input RealInput | watLev | Measured water level |
| output BooleanOutput | yMakUp | Makeup water valve On-Off status |
Modelica definition
block WaterLevel
"Sequences to control water level in cooling tower"
parameter Real watLevMin(
final min=0)
"Minimum cooling tower water level recommended by manufacturer";
parameter Real watLevMax(
final min=0)
"Maximum cooling tower water level recommended by manufacturer";
Buildings.Controls.OBC.CDL.Interfaces.RealInput watLev
"Measured water level";
Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput yMakUp
"Makeup water valve On-Off status";
protected
Buildings.Controls.OBC.CDL.Reals.Hysteresis hys(
final uLow=watLevMin,
final uHigh=watLevMax)
"Check if water level is lower than minimum level";
Buildings.Controls.OBC.CDL.Logical.Not not1
"Check if it should add water";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant minWatLev(
final k=watLevMin) "Minimum water level";
Buildings.Controls.OBC.CDL.Reals.Sources.Constant maxWatLev(
final k=watLevMax) "Maximum water level";
Buildings.Controls.OBC.CDL.Utilities.Assert assMes(
final message="The maximum level has to be greater than the minimum level.")
"Print warning when the maximum level is not set to be greater than the minimum level";
Buildings.Controls.OBC.CDL.Reals.Greater greEqu
"Check if maximum level is set to be greater than minimum level";
equation
connect(watLev, hys.u);
connect(hys.y, not1.u);
connect(not1.y, yMakUp);
connect(maxWatLev.y, greEqu.u1);
connect(minWatLev.y, greEqu.u2);
connect(greEqu.y, assMes.u);
end WaterLevel;