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Better humidity control for chilled water coils and for AirloopHVAC:UnitarySystem #7215

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merged 18 commits into from
Mar 20, 2019
Merged

Better humidity control for chilled water coils and for AirloopHVAC:UnitarySystem #7215

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cb6f108
Temporary fix in GetCoilDesFlowT to protect against array bounds viol…
mjwitte Mar 8, 2019
3adf350
UnitarySystem fix humidity setpoint controls
mjwitte Mar 8, 2019
865c9f0
Merge remote-tracking branch 'remotes/origin/develop' into ChwCoilHum…
mjwitte Mar 9, 2019
53543cb
ChW controller improve temperature and humidity control
mjwitte Mar 10, 2019
7683df8
ChW controller - delete now unused variables
mjwitte Mar 11, 2019
6c08857
Revised fix in GetCoilDesFlowT to protect against array bounds violat…
mjwitte Mar 11, 2019
119c5bc
ChW controller - cleanup and move humctrl check into HVACControllers
mjwitte Mar 11, 2019
9451557
ChW controller - remove unused FirstHVACIteration args
mjwitte Mar 11, 2019
d136c4c
SetActuatedBranchFlowRate - avoid array bounds errors - move early es…
mjwitte Mar 11, 2019
56330bd
GetCoilDesFlowT_NoPeak - new unit test and cleanup
mjwitte Mar 11, 2019
ee06f4e
HVACControllers_CheckTempAndHumRatCtrl unit test
mjwitte Mar 11, 2019
0bd833d
Merge remote-tracking branch 'remotes/origin/develop' into ChwCoilHum…
mjwitte Mar 12, 2019
3f5a7e2
UnitarySystemModel_WaterCoilSPControl_Latent unit test
mjwitte Mar 12, 2019
4471a4e
ChW controller - vary offset only if needed for humidity control
mjwitte Mar 12, 2019
c029acf
Merge remote-tracking branch 'remotes/origin/develop' into ChwCoilHum…
mjwitte Mar 18, 2019
7fda469
UnitarySystem humidity controls - set node conditions in DX calc func…
mjwitte Mar 18, 2019
7883673
UnitarySystem humidity controls - fix unit test
mjwitte Mar 18, 2019
040fa15
UnitarySystem humidity controls - fix another unit test
mjwitte Mar 18, 2019
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88 changes: 18 additions & 70 deletions src/EnergyPlus/HVACControllers.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1280,54 +1280,23 @@ namespace HVACControllers {
}

} else if (SELECT_CASE_var == iTemperatureAndHumidityRatio) { // 'TemperatureAndHumidityRatio'
ControllerProps(ControlNum).SensedValue = Node(SensedNode).Temp;
// Setpoint temp calculated once each HVAC time step to identify approach temp and whether or not humrat control is necessary
// WARNING: The scheme for computing the setpoint for the dual temperature and humidity ratio
// control strategy breaks down whenever the sensed node temperature is modified by
// a controller fired after the current one. Indeed the final sensed node temperature
// is likely to have changed in the meantime if the other controller is active,
// thereby invalidating the setpoint calculation for the other controller performed
// earlier on the air loop.
if (ControllerProps(ControlNum).HumRatCtrlOverride) {
// Humidity ratio control
ControllerProps(ControlNum).SensedValue = Node(SensedNode).HumRat;
} else {
// Temperature control
ControllerProps(ControlNum).SensedValue = Node(SensedNode).Temp;
}
if (!ControllerProps(ControlNum).IsSetPointDefinedFlag) {
// NOTE: For TEMPANDHUMRAT control the computed value ControllerProps(ControlNum)%SetPointValue
// depends on:
// - Node(SensedNode)%HumRatMax
// - Node(SensedNode)%Temp
// - Node(SensedNode)%HumRat
if ((Node(SensedNode).HumRatMax > 0) && (Node(SensedNode).HumRat > Node(SensedNode).HumRatMax)) {
// Setpoint can only be computed once per time step
// Check if outlet air humidity ratio is greater than the set point. If so, calculate new temperature based set point.
// See routine CalcSimpleController() for the sequence of operations.
// Calculate the approach temperature (difference between SA dry-bulb temp and SA dew point temp)
ApproachTemp = Node(SensedNode).Temp - PsyTdpFnWPb(Node(SensedNode).HumRat, OutBaroPress);
// Calculate the dew point temperature at the SA humidity ratio setpoint
DesiredDewPoint = PsyTdpFnWPb(Node(SensedNode).HumRatMax, OutBaroPress);
// Adjust the calculated dew point temperature by the approach temp. Should be within 0.3C of air temperature.
HumidityControlTempSetPoint = DesiredDewPoint + min(0.3, ApproachTemp);
// NOTE: The next line introduces a potential discontinuity into the residual function
// which could prevent the root finder from finding the root it if were done at each
// controller iteration. For this reason we perform the setpoint calculation only
// once at the beginning of the controller and air loop simulation.
// Use lower of temperature and humidity based set point.
// See routine CalcSimpleController() for the sequence of operations.
ControllerProps(ControlNum).SetPointValue = min(
Node(SensedNode).TempSetPoint,
HumidityControlTempSetPoint); // Pure temperature setpoint | Temperature setpoint to achieve the humidity ratio setpoint
// Don't allow set point temperature to be below the actuator node water temperature
ControllerProps(ControlNum).SetPointValue =
max(ControllerProps(ControlNum).SetPointValue, Node(ControllerProps(ControlNum).ActuatedNode).Temp);
// Overwrite the "pure" temperature setpoint with the actual setpoint that takes into
// account the humidity ratio setpoint.
// NOTE: Check that this does not create side-effects somewhere else in the code.
Node(SensedNode).TempSetPoint = ControllerProps(ControlNum).SetPointValue;
// Finally indicate thate the setpoint has been computed
ControllerProps(ControlNum).IsSetPointDefinedFlag = true;
if (ControllerProps(ControlNum).HumRatCtrlOverride) {
// Humidity ratio control
ControllerProps(ControlNum).SetPointValue = Node(SensedNode).HumRatMax;
} else {
// Pure temperature setpoint control strategy
ControllerProps(ControlNum).SetPointValue = Node(SensedNode).TempSetPoint;
// Finally indicate thate the setpoint has been computed
ControllerProps(ControlNum).IsSetPointDefinedFlag = true;
}
// Finally indicate thate the setpoint has been computed
ControllerProps(ControlNum).IsSetPointDefinedFlag = true;
}

} else if (SELECT_CASE_var == iHumidityRatio) { // 'HumidityRatio'
Expand Down Expand Up @@ -1465,6 +1434,10 @@ namespace HVACControllers {
(0.001 / (2100.0 * max(ControllerProps(ControlNum).MaxVolFlowActuated, SmallWaterVolFlow))) * (HVACEnergyToler / 10.0);
// do not let the controller tolerance exceed 1/10 of the loop temperature tolerance.
ControllerProps(ControlNum).Offset = min(0.1 * HVACTemperatureToler, ControllerProps(ControlNum).Offset);
if (ControllerProps(ControlNum).ControlVar == HVACControllers::iTemperatureAndHumidityRatio) {
// for temperature and humidity control, need tighter tolerance if humidity control kicks in
ControllerProps(ControlNum).Offset = ControllerProps(ControlNum).Offset*0.1;
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Would be nice to be able to trigger a tighter tolerance only when HumRatCtrlOverride = true.

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I tried that first but it didn't work. There's some initial setup step that I couldn't find that includes the offset.

}
ReportSizingOutput(ControllerProps(ControlNum).ControllerType,
ControllerProps(ControlNum).ControllerName,
"Controller Convergence Tolerance",
Expand Down Expand Up @@ -1587,33 +1560,8 @@ namespace HVACControllers {
FindRootSimpleController(ControlNum, FirstHVACIteration, IsConvergedFlag, IsUpToDateFlag, ControllerName);

} else {

// We need to evaluate the sensed node temperature with the max actuated value before
// we can compute the actual setpoint for the dual humidity ratio / temperature strategy.
{
auto const SELECT_CASE_var(ControllerProps(ControlNum).ControlVar);
if ((SELECT_CASE_var == iTemperature) || (SELECT_CASE_var == iHumidityRatio) || (SELECT_CASE_var == iFlow)) {
// Always start with min point by default for the other control strategies
ControllerProps(ControlNum).NextActuatedValue = RootFinders(ControlNum).MinPoint.X;

} else if (SELECT_CASE_var == iTemperatureAndHumidityRatio) {
if (!ControllerProps(ControlNum).IsSetPointDefinedFlag) {
// Always start with max point if setpoint not yet computed. See routine InitController().
ControllerProps(ControlNum).NextActuatedValue = RootFinders(ControlNum).MaxPoint.X;
} else {
// If setpoint already exists (i.e., HumRatMax <= 0) then try min point first as in simple
// temperature control case.
ControllerProps(ControlNum).NextActuatedValue = RootFinders(ControlNum).MinPoint.X;
}

} else {
// Should never happen
ShowSevereError("CalcSimpleController: HVAC controller failed at " + CreateHVACStepFullString());
ShowContinueError(" Controller name=" + ControllerProps(ControlNum).ControllerName);
ShowContinueError(" Unrecognized control variable type=" + TrimSigDigits(ControllerProps(ControlNum).ControlVar));
ShowFatalError("Preceding error causes program termination.");
}
}
// Always start with min point by default
ControllerProps(ControlNum).NextActuatedValue = RootFinders(ControlNum).MinPoint.X;
}

// Process current iterate and compute next candidate if needed
Expand Down
4 changes: 3 additions & 1 deletion src/EnergyPlus/HVACControllers.hh
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Original file line number Diff line number Diff line change
Expand Up @@ -233,6 +233,8 @@ namespace HVACControllers {
bool BypassControllerCalc; // set true for OA sys water coils
int AirLoopControllerIndex; // index to controller on specific air loop

bool HumRatCtrlOverride; // true if TemperatureAndHumidityRatio control switches to humidity ratio control

// Default Constructor
ControllerPropsType()
: ControllerType_Num(ControllerSimple_Type), ControlVar(iNoControlVariable), ActuatorVar(0), Action(iNoAction), InitFirstPass(true),
Expand All @@ -242,7 +244,7 @@ namespace HVACControllers {
ActuatedNodePlantLoopNum(0), ActuatedNodePlantLoopSide(0), ActuatedNodePlantLoopBranchNum(0), SensedNode(0),
IsSetPointDefinedFlag(false), SetPointValue(0.0), SensedValue(0.0), DeltaSensed(0.0), Offset(0.0), HumRatCntrlType(0), Range(0.0),
Limit(0.0), TraceFileUnit(0), FirstTraceFlag(true), BadActionErrCount(0), BadActionErrIndex(0), FaultyCoilSATFlag(false),
FaultyCoilSATIndex(0), FaultyCoilSATOffset(0.0), BypassControllerCalc(false), AirLoopControllerIndex(0)
FaultyCoilSATIndex(0), FaultyCoilSATOffset(0.0), BypassControllerCalc(false), AirLoopControllerIndex(0), HumRatCtrlOverride(false)
{
}
};
Expand Down
25 changes: 15 additions & 10 deletions src/EnergyPlus/ReportSizingManager.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -4441,7 +4441,7 @@ namespace ReportSizingManager {
int PeakLoadType;
int DDAtTotPeak;
int TimeStepAtTotPeak;
int TimeStepAtPeak;
int TimeStepAtPeak(0);
Real64 ZoneCoolLoadSum(0); // sum of zone cooling loads at the peak [W]
Real64 AvgZoneTemp(0); // average zone temperature [C]
Real64 AvgSupTemp; // average supply temperature for bypass control [C]
Expand All @@ -4451,23 +4451,28 @@ namespace ReportSizingManager {
CoolCapCtrl = SysSizInput(SysNum).CoolCapControl;
PeakLoadType = SysSizInput(SysNum).CoolingPeakLoadType;
DDAtSensPeak = SysSizPeakDDNum(SysNum).SensCoolPeakDD;
TimeStepAtSensPeak = SysSizPeakDDNum(SysNum).TimeStepAtSensCoolPk(DDAtSensPeak);
DDAtFlowPeak = SysSizPeakDDNum(SysNum).CoolFlowPeakDD;
TimeStepAtFlowPeak = SysSizPeakDDNum(SysNum).TimeStepAtCoolFlowPk(DDAtFlowPeak);
DDAtTotPeak = SysSizPeakDDNum(SysNum).TotCoolPeakDD;
TimeStepAtTotPeak = SysSizPeakDDNum(SysNum).TimeStepAtTotCoolPk(DDAtTotPeak);
if (DDAtSensPeak > 0) {
TimeStepAtSensPeak = SysSizPeakDDNum(SysNum).TimeStepAtSensCoolPk(DDAtSensPeak);
DDAtFlowPeak = SysSizPeakDDNum(SysNum).CoolFlowPeakDD;
TimeStepAtFlowPeak = SysSizPeakDDNum(SysNum).TimeStepAtCoolFlowPk(DDAtFlowPeak);
DDAtTotPeak = SysSizPeakDDNum(SysNum).TotCoolPeakDD;
TimeStepAtTotPeak = SysSizPeakDDNum(SysNum).TimeStepAtTotCoolPk(DDAtTotPeak);

if (PeakLoadType == TotalCoolingLoad) {
TimeStepAtPeak = TimeStepAtTotPeak;
} else {
TimeStepAtPeak = TimeStepAtSensPeak;
if (PeakLoadType == TotalCoolingLoad) {
TimeStepAtPeak = TimeStepAtTotPeak;
} else {
TimeStepAtPeak = TimeStepAtSensPeak;
}
}
if (CoolCapCtrl == VAV) {
DesExitTemp = FinalSysSizing(SysNum).CoolSupTemp;
DesFlow = FinalSysSizing(SysNum).MassFlowAtCoolPeak / StdRhoAir;
} else if (CoolCapCtrl == OnOff) {
DesExitTemp = FinalSysSizing(SysNum).CoolSupTemp;
DesFlow = DataAirFlowUsedForSizing;
} else if (TimeStepAtPeak == 0) {
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TimeStepAtPeak can't be 0 if VAV or OnOff fan control is used? If so then this line won't get hit. This IF test should be first in list?

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Oh, I see. You put this IF test before those that use TimeStepAtPeak.

ShowFatalError("GetCoilDesFlow: AirLoopHVAC=" + SysSizInput(SysNum).AirPriLoopName +
" Central Cooling Capacity Control Method requires zone thermostats to calculate timestep loads.");
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You can still have a no design load condition (and therefore a 0 for time step at peak) even though a Tstat is used. Remember when zone return temp at heating peak was 0 and TU coils weren't sizing correctly? It's the combination of Tstat temp (i.e., zone temp during sizing) and supply air temp that yields a non-zero zone mass flow rate. Isn't there another way to know if a Tstat is used?

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You're right, even with a tstat, there could be zero peak. So, should these methods throw a warning if there's no peak day/time and revert to one of the other methods?

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Maybe change the warning text to say exactly what has happened (inside the else if's below) and revert to sizing with CoolSupTemp and MassFlowAtCoolPeak?

} else if (CoolCapCtrl == VT) {
if (FinalSysSizing(SysNum).CoolingPeakLoadType == SensibleCoolingLoad) {
ZoneCoolLoadSum = CalcSysSizing(SysNum).SumZoneCoolLoadSeq(TimeStepAtPeak);
Expand Down
28 changes: 28 additions & 0 deletions src/EnergyPlus/SimAirServingZones.cc
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Expand Up @@ -2864,6 +2864,9 @@ namespace SimAirServingZones {
// E.g., actuator inlet water flow
for (int AirLoopControlNum = 1; AirLoopControlNum <= PrimaryAirSystem(AirLoopNum).NumControllers; ++AirLoopControlNum) {

// For temperature and humidity control reset humidity control override
HVACControllers::ControllerProps(PrimaryAirSystem(AirLoopNum).ControllerIndex(AirLoopControlNum)).HumRatCtrlOverride = false;

// BypassOAController is true here since we do not want to simulate the controller if it has already been simulated in the OA system
// ControllerConvergedFlag is returned true here for water coils in OA system
ManageControllers(PrimaryAirSystem(AirLoopNum).ControllerName(AirLoopControlNum),
Expand Down Expand Up @@ -2960,6 +2963,31 @@ namespace SimAirServingZones {
// not converge
ControllerConvergedFlag = PrimaryAirSystem(AirLoopNum).ControlConverged(AirLoopControlNum);
IsUpToDateFlag = true;
} else {
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This will require multiple more iterations of the air loop components. Wouldn't it be better to use the lesser of T and TdpFw as the temperature set point up at line 1283 - 1289 of HVACControllers?

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I can try that on a separate branch, but I think it will over-dehumidify.

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Or use T and TdpFw as a trigger to choose which set point to use, temperature or humidity ratio.

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No, don't need to try that. The humidity ratio setpoint is 0.011388 which is roughly Tdp=15.9C. There are many hours where the coil can meet the humidity ratio setpoint with a leaving temperature of 16-17C, and there are many hours where the leaving air is saturated. That's why this needs to switch gears and can't just use Tdp.

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Hmm, how can Tdp come out lower than supply air T? If a dry coil then yes, but a wet coil? Not your problem at this point.

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'cause the water temp is well below Tdp, and some of the air bypasses the coil, so the resulting mix can be drier than saturation.

{
auto &thisController(HVACControllers::ControllerProps(PrimaryAirSystem(AirLoopNum).ControllerIndex(AirLoopControlNum)));
if (thisController.ControlVar == HVACControllers::iTemperatureAndHumidityRatio) {
// For temperature and humidity control, after temperature control is converged, check if humidity setpoint is met
if (!thisController.HumRatCtrlOverride) {
if (Node(thisController.SensedNode).HumRat > (Node(thisController.SensedNode).HumRatMax + thisController.Offset)) {
// Turn on humdity control and restart controller
ControllerConvergedFlag = false;
thisController.HumRatCtrlOverride = true;
IsUpToDateFlag = false;
ManageControllers(PrimaryAirSystem(AirLoopNum).ControllerName(AirLoopControlNum),
PrimaryAirSystem(AirLoopNum).ControllerIndex(AirLoopControlNum),
FirstHVACIteration,
AirLoopNum,
iControllerOpWarmRestart,
ControllerConvergedFlag,
IsUpToDateFlag,
BypassOAController,
AllowWarmRestartFlag);
SimAirLoopComponents(AirLoopNum, FirstHVACIteration);
}
}
}
}
}

} // End of the Convergence Iteration
Expand Down
8 changes: 6 additions & 2 deletions src/EnergyPlus/UnitarySystem.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -10406,7 +10406,7 @@ namespace UnitarySystems {
// and if coolReheat, check hum rat as well
if (((NoLoadTempOut - DesOutTemp) < Acc) && ((NoLoadHumRatOut - DesOutHumRat) < HumRatAcc)) {
PartLoadFrac = 0.0;
} else if (SensibleLoad) { // need to turn on compressor to see if load is met
} else { // need to turn on compressor to see if load is met
PartLoadFrac = 1.0;
CompOn = 1;
m_WSHPRuntimeFrac = 1.0;
Expand Down Expand Up @@ -10571,7 +10571,9 @@ namespace UnitarySystems {
(this->m_TESOpMode == PackagedThermalStorageCoil::OffMode ||
this->m_TESOpMode == PackagedThermalStorageCoil::ChargeOnlyMode)) {
PartLoadFrac = 0.0;
} else {
} else if (!SensibleLoad) {
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Highlights an issue with all coils types when no sensible load exists and a latent load does. Logic at top of function could skip sensible PLR calcs and go directly to latent calcs. Sensible calcs are inside of if(SensibleLoad || LatentLoad) block.

PartLoadFrac = 0.0;
} else if (SensibleLoad) {

Par[9] = double(AirLoopNum);
Par[10] = 0.0;
Expand Down Expand Up @@ -10866,6 +10868,7 @@ namespace UnitarySystems {
FullOutput = DataLoopNode::Node(InletNode).MassFlowRate *
(Psychrometrics::PsyHFnTdbW(DataLoopNode::Node(OutletNode).Temp, DataLoopNode::Node(OutletNode).HumRat) -
Psychrometrics::PsyHFnTdbW(DataLoopNode::Node(InletNode).Temp, DataLoopNode::Node(OutletNode).HumRat));
FullLoadHumRatOut = DataLoopNode::Node(OutletNode).HumRat;

// Check to see if the system can meet the load with the compressor off
// If NoOutput is lower than (more cooling than required) or very near the ReqOutput, do not run the compressor
Expand Down Expand Up @@ -10906,6 +10909,7 @@ namespace UnitarySystems {
FullOutput = DataLoopNode::Node(InletNode).MassFlowRate *
(Psychrometrics::PsyHFnTdbW(DataLoopNode::Node(OutletNode).Temp, DataLoopNode::Node(InletNode).HumRat) -
Psychrometrics::PsyHFnTdbW(DataLoopNode::Node(InletNode).Temp, DataLoopNode::Node(InletNode).HumRat));
FullLoadHumRatOut = DataLoopNode::Node(OutletNode).HumRat;

// Since we are cooling, we expect FullOutput to be < 0 and FullOutput < NoCoolOutput
// Check that this is the case; IF not set PartLoadFrac = 0.0 (off) and return
Expand Down