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Fix #10663 - Fan runtime fraction < 1 when flow rate scaling using DesignSpecification:ZoneHVAC:Sizing #10673

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Fix #10663 - Fan runtime fraction < 1 when flow rate scaling using DesignSpecification:ZoneHVAC:Sizing #10673

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9d0bef8
Improve an existing unit test (I plan to use a variation of this)
jmarrec Aug 20, 2024
dddaa5a
New unit test for #10663
jmarrec Aug 20, 2024
52ffb00
Take a reference directly
jmarrec Aug 19, 2024
5dbc7b1
Revamp the routine to take more references to shorten the code, scope…
jmarrec Aug 20, 2024
f472e96
Fix existing logic error related to Cooling Capacity sizing
jmarrec Aug 19, 2024
a5d32de
Set CoolingAirFlow flag in WindowAC so fan is sized by the WindowAC
jmarrec Aug 20, 2024
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180 changes: 86 additions & 94 deletions src/EnergyPlus/WindowAC.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -892,8 +892,6 @@ namespace WindowAC {
// METHODOLOGY EMPLOYED:
// Obtains flow rates from the zone or system sizing arrays

auto &ZoneEqSizing(state.dataSize->ZoneEqSizing);

// Using/Aliasing
using namespace DataSizing;
using HVAC::CoolingCapacitySizing;
Expand All @@ -902,30 +900,19 @@ namespace WindowAC {
static constexpr std::string_view RoutineName("SizeWindowAC: "); // include trailing blank space

// SUBROUTINE LOCAL VARIABLE DECLARATIONS:
Real64 MaxAirVolFlowDes; // Autosized maximum air flow for reporting
Real64 MaxAirVolFlowUser; // Hardsized maximum air flow for reporting
Real64 OutAirVolFlowDes; // Autosized outdoor air flow for reporting
Real64 OutAirVolFlowUser; // Hardsized outdoor ari flow for reporting
bool IsAutoSize; // Indicator to autosize
std::string CompName; // component name
std::string CompType; // component type
std::string SizingString; // input field sizing description (e.g., Nominal Capacity)
Real64 TempSize; // autosized value of coil input field
int FieldNum = 2; // IDD numeric field number where input field description is found
int SizingMethod; // Integer representation of sizing method name (e.g., CoolingAirflowSizing, HeatingAirflowSizing, CoolingCapacitySizing,
// HeatingCapacitySizing, etc.)
bool PrintFlag; // TRUE when sizing information is reported in the eio file
int zoneHVACIndex; // index of zoneHVAC equipment sizing specification
int SAFMethod(0); // supply air flow rate sizing method (SupplyAirFlowRate, FlowPerFloorArea, FractionOfAutosizedCoolingAirflow,
// FractionOfAutosizedHeatingAirflow ...)
int CapSizingMethod(0); // capacity sizing methods (HeatingDesignCapacity, CapacityPerFloorArea, FractionOfAutosizedCoolingCapacity, and
// FractionOfAutosizedHeatingCapacity )

IsAutoSize = false;
MaxAirVolFlowDes = 0.0;
MaxAirVolFlowUser = 0.0;
OutAirVolFlowDes = 0.0;
OutAirVolFlowUser = 0.0;
auto &windowAC = state.dataWindowAC->WindAC(WindACNum);

Real64 MaxAirVolFlowDes = 0.0; // Autosized maximum air flow for reporting
Real64 MaxAirVolFlowUser = 0.0; // Hardsized maximum air flow for reporting
Real64 OutAirVolFlowDes = 0.0; // Autosized outdoor air flow for reporting
Real64 OutAirVolFlowUser = 0.0; // Hardsized outdoor ari flow for reporting
bool IsAutoSize = false; // Indicator to autosize
std::string const CompType = "ZoneHVAC:WindowAirConditioner"; // component name
std::string const CompName = windowAC.Name; // component type
Real64 TempSize = AutoSize; // autosized value of coil input field
int FieldNum = 2; // IDD numeric field number where input field description is found
bool PrintFlag = false; // TRUE when sizing information is reported in the eio file

state.dataSize->DataFracOfAutosizedCoolingAirflow = 1.0;
state.dataSize->DataFracOfAutosizedHeatingAirflow = 1.0;
state.dataSize->DataFracOfAutosizedCoolingCapacity = 1.0;
Expand All @@ -934,141 +921,146 @@ namespace WindowAC {
state.dataSize->ZoneHeatingOnlyFan = false;
state.dataSize->ZoneCoolingOnlyFan = true;
state.dataSize->DataScalableCapSizingON = false;
CompType = "ZoneHVAC:WindowAirConditioner";
CompName = state.dataWindowAC->WindAC(WindACNum).Name;
state.dataSize->DataZoneNumber = state.dataWindowAC->WindAC(WindACNum).ZonePtr;
state.dataSize->DataFanType = state.dataWindowAC->WindAC(WindACNum).fanType;
state.dataSize->DataFanIndex = state.dataWindowAC->WindAC(WindACNum).FanIndex;
state.dataSize->DataFanPlacement = state.dataWindowAC->WindAC(WindACNum).fanPlace;
state.dataSize->DataZoneNumber = windowAC.ZonePtr;
state.dataSize->DataFanType = windowAC.fanType;
state.dataSize->DataFanIndex = windowAC.FanIndex;
state.dataSize->DataFanPlacement = windowAC.fanPlace;

if (state.dataSize->CurZoneEqNum > 0) {
if (state.dataWindowAC->WindAC(WindACNum).HVACSizingIndex > 0) {
zoneHVACIndex = state.dataWindowAC->WindAC(WindACNum).HVACSizingIndex;
auto &zoneEqSizing = state.dataSize->ZoneEqSizing(state.dataSize->CurZoneEqNum);

if (windowAC.HVACSizingIndex > 0) {
// N1 , \field Maximum Supply Air Flow Rate
SizingMethod = HVAC::CoolingAirflowSizing;

auto const &zoneHVACSizing = state.dataSize->ZoneHVACSizing(windowAC.HVACSizingIndex);

// Integer representation of sizing method name (e.g., CoolingAirflowSizing, HeatingAirflowSizing, CoolingCapacitySizing,
// HeatingCapacitySizing, etc.
int SizingMethod = HVAC::CoolingAirflowSizing;
PrintFlag = true;
SAFMethod = state.dataSize->ZoneHVACSizing(zoneHVACIndex).CoolingSAFMethod;
ZoneEqSizing(state.dataSize->CurZoneEqNum).SizingMethod(SizingMethod) = SAFMethod;
// supply air flow rate sizing method (SupplyAirFlowRate, FlowPerFloorArea, FractionOfAutosizedCoolingAirflow,
// FractionOfAutosizedHeatingAirflow)
int const SAFMethod = zoneHVACSizing.CoolingSAFMethod;
zoneEqSizing.SizingMethod(SizingMethod) = SAFMethod;
if (SAFMethod == None || SAFMethod == SupplyAirFlowRate || SAFMethod == FlowPerFloorArea ||
SAFMethod == FractionOfAutosizedCoolingAirflow) {
if (SAFMethod == SupplyAirFlowRate) {
if (state.dataSize->ZoneHVACSizing(zoneHVACIndex).MaxCoolAirVolFlow > 0.0) {
ZoneEqSizing(state.dataSize->CurZoneEqNum).AirVolFlow = state.dataSize->ZoneHVACSizing(zoneHVACIndex).MaxCoolAirVolFlow;
ZoneEqSizing(state.dataSize->CurZoneEqNum).SystemAirFlow = true;
if (zoneHVACSizing.MaxCoolAirVolFlow > 0.0) {
zoneEqSizing.AirVolFlow = zoneHVACSizing.MaxCoolAirVolFlow;
zoneEqSizing.SystemAirFlow = true;
}
TempSize = state.dataSize->ZoneHVACSizing(zoneHVACIndex).MaxCoolAirVolFlow;
TempSize = zoneHVACSizing.MaxCoolAirVolFlow;
} else if (SAFMethod == FlowPerFloorArea) {
ZoneEqSizing(state.dataSize->CurZoneEqNum).SystemAirFlow = true;
ZoneEqSizing(state.dataSize->CurZoneEqNum).AirVolFlow = state.dataSize->ZoneHVACSizing(zoneHVACIndex).MaxCoolAirVolFlow *
state.dataHeatBal->Zone(state.dataSize->DataZoneNumber).FloorArea;
TempSize = ZoneEqSizing(state.dataSize->CurZoneEqNum).AirVolFlow;
zoneEqSizing.SystemAirFlow = true;
zoneEqSizing.AirVolFlow =
zoneHVACSizing.MaxCoolAirVolFlow * state.dataHeatBal->Zone(state.dataSize->DataZoneNumber).FloorArea;
TempSize = zoneEqSizing.AirVolFlow;
state.dataSize->DataScalableSizingON = true;
} else if (SAFMethod == FractionOfAutosizedCoolingAirflow) {
state.dataSize->DataFracOfAutosizedCoolingAirflow = state.dataSize->ZoneHVACSizing(zoneHVACIndex).MaxCoolAirVolFlow;
state.dataSize->DataFracOfAutosizedCoolingAirflow = zoneHVACSizing.MaxCoolAirVolFlow;
TempSize = AutoSize;
state.dataSize->DataScalableSizingON = true;
} else {
TempSize = state.dataSize->ZoneHVACSizing(zoneHVACIndex).MaxCoolAirVolFlow;
TempSize = zoneHVACSizing.MaxCoolAirVolFlow;
}
bool errorsFound = false;
CoolingAirFlowSizer sizingCoolingAirFlow;
std::string stringOverride = "Maximum Supply Air Flow Rate [m3/s]";
if (state.dataGlobal->isEpJSON) stringOverride = "maximum_supply_air_flow_rate [m3/s]";
if (state.dataGlobal->isEpJSON) {
stringOverride = "maximum_supply_air_flow_rate [m3/s]";
}
sizingCoolingAirFlow.overrideSizingString(stringOverride);
// sizingCoolingAirFlow.setHVACSizingIndexData(FanCoil(FanCoilNum).HVACSizingIndex);
// sizingCoolingAirFlow.setHVACSizingIndexData(windowAC.HVACSizingIndex);
sizingCoolingAirFlow.initializeWithinEP(state, CompType, CompName, PrintFlag, RoutineName);
state.dataWindowAC->WindAC(WindACNum).MaxAirVolFlow = sizingCoolingAirFlow.size(state, TempSize, errorsFound);
windowAC.MaxAirVolFlow = sizingCoolingAirFlow.size(state, TempSize, errorsFound);

} else if (SAFMethod == FlowPerCoolingCapacity) {
SizingMethod = CoolingCapacitySizing;
SizingMethod = HVAC::CoolingCapacitySizing;
TempSize = AutoSize;
PrintFlag = false;
state.dataSize->DataScalableSizingON = true;
state.dataSize->DataFlowUsedForSizing = state.dataSize->FinalZoneSizing(state.dataSize->CurZoneEqNum).DesCoolVolFlow;
if (state.dataSize->ZoneHVACSizing(zoneHVACIndex).CoolingCapMethod == FractionOfAutosizedCoolingCapacity) {
state.dataSize->DataFracOfAutosizedCoolingCapacity = state.dataSize->ZoneHVACSizing(zoneHVACIndex).ScaledCoolingCapacity;
if (zoneHVACSizing.CoolingCapMethod == FractionOfAutosizedCoolingCapacity) {
state.dataSize->DataFracOfAutosizedCoolingCapacity = zoneHVACSizing.ScaledCoolingCapacity;
}
bool errorsFound = false;
CoolingCapacitySizer sizerCoolingCapacity;
sizerCoolingCapacity.overrideSizingString(SizingString);
sizerCoolingCapacity.overrideSizingString("");
sizerCoolingCapacity.initializeWithinEP(state, CompType, CompName, PrintFlag, RoutineName);
state.dataSize->DataCapacityUsedForSizing = sizerCoolingCapacity.size(state, TempSize, errorsFound);
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Yes, this does look correct. Call the cooling capacity sizer which uses zone design air flow.

state.dataSize->DataFlowPerCoolingCapacity = state.dataSize->ZoneHVACSizing(zoneHVACIndex).MaxCoolAirVolFlow;
state.dataSize->DataFlowPerCoolingCapacity = zoneHVACSizing.MaxCoolAirVolFlow;
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Set the fraction of air flow here

PrintFlag = true;
TempSize = AutoSize;
errorsFound = false;
CoolingAirFlowSizer sizingCoolingAirFlow;
std::string stringOverride = "Maximum Supply Air Flow Rate [m3/s]";
if (state.dataGlobal->isEpJSON) stringOverride = "maximum_supply_air_flow_rate [m3/s]";
if (state.dataGlobal->isEpJSON) {
stringOverride = "maximum_supply_air_flow_rate [m3/s]";
}
sizingCoolingAirFlow.overrideSizingString(stringOverride);
// sizingCoolingAirFlow.setHVACSizingIndexData(FanCoil(FanCoilNum).HVACSizingIndex);
// sizingCoolingAirFlow.setHVACSizingIndexData(windowAC.HVACSizingIndex);
sizingCoolingAirFlow.initializeWithinEP(state, CompType, CompName, PrintFlag, RoutineName);
state.dataWindowAC->WindAC(WindACNum).MaxAirVolFlow = sizingCoolingAirFlow.size(state, TempSize, errorsFound);
windowAC.MaxAirVolFlow = sizingCoolingAirFlow.size(state, TempSize, errorsFound);
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@rraustad rraustad Aug 27, 2024 •
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And then size that new air flow rate here. You should also reset state.dataSize->DataFlowPerCoolingCapacity here to be a flow rate instead of a fraction.

}
// DataScalableSizingON = false;

// initialize capacity sizing variables: cooling
CapSizingMethod = state.dataSize->ZoneHVACSizing(zoneHVACIndex).CoolingCapMethod;
ZoneEqSizing(state.dataSize->CurZoneEqNum).SizingMethod(SizingMethod) = CapSizingMethod;
// capacity sizing methods (HeatingDesignCapacity, CapacityPerFloorArea, FractionOfAutosizedCoolingCapacity, and
// FractionOfAutosizedHeatingCapacity )
int const CapSizingMethod = zoneHVACSizing.CoolingCapMethod;
zoneEqSizing.SizingMethod(SizingMethod) = CapSizingMethod;
Comment on lines +1008 to +1011
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Note: I'm not sure if this is right... (this is pre-existing)

At this point in time, SizingMethod is either HVAC::CoolingAirflowSizing, or HVAC::CoolingCapacitySizing if the SAFMethod is FlowPerCoolingCapacity.

I think the intent here is to set the CoolingCapacitySizing method specifically, so it should be HVAC::CoolingCapacitySizing, right?

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The intent for FlowPerCoolingCapacity is:

  • calc design capacity using zone design air flow rate
  • set fraction that will adjust zone design air flow when air flow is sized (which will also adjust capacity when capacity is sized)

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just to be clear, you're saying this is currently correct right?

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@rraustad rraustad Aug 27, 2024 •
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Then the next time you call using HVAC::CoolingCapacitySizing the adjusted air flow rate would be used. It appears to me that the capacity sizer should be called here using SizingMethod = HVAC::CoolingCapacitySizing;. It looks like 1) state.dataSize->DataFlowUsedForSizing was not reset above to be an air flow rate (and DataFlowPerCoolingCapacity should be reset to 0), and 2) the sizing method should be explicitly set for capacity sizing (right now is looks to still be fraction of capacity).

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@rraustad rraustad Aug 27, 2024 •
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If you single step this a couple times you should see the capacity getting set using zone design air flow, the air flow being adjusted based on capacity, and the capacity being calculated again using the new air flow rate.

if (CapSizingMethod == CoolingDesignCapacity || CapSizingMethod == CapacityPerFloorArea ||
CapSizingMethod == FractionOfAutosizedCoolingCapacity) {
if (CapSizingMethod == HeatingDesignCapacity) {
if (state.dataSize->ZoneHVACSizing(zoneHVACIndex).ScaledCoolingCapacity > 0.0) {
ZoneEqSizing(state.dataSize->CurZoneEqNum).CoolingCapacity = true;
ZoneEqSizing(state.dataSize->CurZoneEqNum).DesCoolingLoad =
state.dataSize->ZoneHVACSizing(zoneHVACIndex).ScaledCoolingCapacity;
if (CapSizingMethod == CoolingDesignCapacity) {
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This was an existing logic error that I noticed

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Good catch. Without example files or unit tests these are hard to find.

if (zoneHVACSizing.ScaledCoolingCapacity > 0.0) {
zoneEqSizing.CoolingCapacity = true;
zoneEqSizing.DesCoolingLoad = zoneHVACSizing.ScaledCoolingCapacity;
}
} else if (CapSizingMethod == CapacityPerFloorArea) {
ZoneEqSizing(state.dataSize->CurZoneEqNum).CoolingCapacity = true;
ZoneEqSizing(state.dataSize->CurZoneEqNum).DesCoolingLoad =
state.dataSize->ZoneHVACSizing(zoneHVACIndex).ScaledCoolingCapacity *
state.dataHeatBal->Zone(state.dataSize->DataZoneNumber).FloorArea;
zoneEqSizing.CoolingCapacity = true;
zoneEqSizing.DesCoolingLoad =
zoneHVACSizing.ScaledCoolingCapacity * state.dataHeatBal->Zone(state.dataSize->DataZoneNumber).FloorArea;
state.dataSize->DataScalableCapSizingON = true;
} else if (CapSizingMethod == FractionOfAutosizedCoolingCapacity) {
state.dataSize->DataFracOfAutosizedCoolingCapacity = state.dataSize->ZoneHVACSizing(zoneHVACIndex).ScaledCoolingCapacity;
state.dataSize->DataFracOfAutosizedCoolingCapacity = zoneHVACSizing.ScaledCoolingCapacity;
state.dataSize->DataScalableCapSizingON = true;
}
}
} else {
// no scalble sizing method has been specified. Sizing proceeds using the method
// no scalable sizing method has been specified. Sizing proceeds using the method
// specified in the zoneHVAC object
// N1 , \field Maximum Supply Air Flow Rate
FieldNum = 1;
PrintFlag = true;
SizingString = state.dataWindowAC->WindACNumericFields(WindACNum).FieldNames(FieldNum) + " [m3/s]";
TempSize = state.dataWindowAC->WindAC(WindACNum).MaxAirVolFlow;
std::string stringOverride = state.dataWindowAC->WindACNumericFields(WindACNum).FieldNames(FieldNum) + " [m3/s]";
TempSize = windowAC.MaxAirVolFlow;
bool errorsFound = false;
SystemAirFlowSizer sizerSystemAirFlow;
sizerSystemAirFlow.overrideSizingString(SizingString);
// sizerSystemAirFlow.setHVACSizingIndexData(FanCoil(FanCoilNum).HVACSizingIndex);
sizerSystemAirFlow.overrideSizingString(stringOverride);
// sizerSystemAirFlow.setHVACSizingIndexData(windowAC.HVACSizingIndex);
sizerSystemAirFlow.initializeWithinEP(state, CompType, CompName, PrintFlag, RoutineName);
state.dataWindowAC->WindAC(WindACNum).MaxAirVolFlow = sizerSystemAirFlow.size(state, TempSize, errorsFound);
windowAC.MaxAirVolFlow = sizerSystemAirFlow.size(state, TempSize, errorsFound);
}
}

if (state.dataWindowAC->WindAC(WindACNum).OutAirVolFlow == AutoSize) {

if (state.dataSize->CurZoneEqNum > 0) {
if (windowAC.OutAirVolFlow == AutoSize) {

CheckZoneSizing(state,
state.dataWindowAC->cWindowAC_UnitTypes(state.dataWindowAC->WindAC(WindACNum).UnitType),
state.dataWindowAC->WindAC(WindACNum).Name);
state.dataWindowAC->WindAC(WindACNum).OutAirVolFlow =
min(state.dataSize->FinalZoneSizing(state.dataSize->CurZoneEqNum).MinOA, state.dataWindowAC->WindAC(WindACNum).MaxAirVolFlow);
if (state.dataWindowAC->WindAC(WindACNum).OutAirVolFlow < SmallAirVolFlow) {
state.dataWindowAC->WindAC(WindACNum).OutAirVolFlow = 0.0;
CheckZoneSizing(state, state.dataWindowAC->cWindowAC_UnitTypes(windowAC.UnitType), windowAC.Name);
windowAC.OutAirVolFlow = min(state.dataSize->FinalZoneSizing(state.dataSize->CurZoneEqNum).MinOA, windowAC.MaxAirVolFlow);
if (windowAC.OutAirVolFlow < SmallAirVolFlow) {
windowAC.OutAirVolFlow = 0.0;
}
BaseSizer::reportSizerOutput(state,
state.dataWindowAC->cWindowAC_UnitTypes(state.dataWindowAC->WindAC(WindACNum).UnitType),
state.dataWindowAC->WindAC(WindACNum).Name,
state.dataWindowAC->cWindowAC_UnitTypes(windowAC.UnitType),
windowAC.Name,
"Maximum Outdoor Air Flow Rate [m3/s]",
state.dataWindowAC->WindAC(WindACNum).OutAirVolFlow);
windowAC.OutAirVolFlow);
}
}

if (state.dataSize->CurZoneEqNum > 0) {
ZoneEqSizing(state.dataSize->CurZoneEqNum).OAVolFlow = state.dataWindowAC->WindAC(WindACNum).OutAirVolFlow;
ZoneEqSizing(state.dataSize->CurZoneEqNum).AirVolFlow = state.dataWindowAC->WindAC(WindACNum).MaxAirVolFlow;
zoneEqSizing.OAVolFlow = windowAC.OutAirVolFlow;
zoneEqSizing.AirVolFlow = windowAC.MaxAirVolFlow;
// Make the Fan be sized by this
zoneEqSizing.CoolingAirFlow = true;
zoneEqSizing.CoolingAirVolFlow = windowAC.MaxAirVolFlow;
Comment on lines +1061 to +1063
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This will size the Fan to match.

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EnergyPlus/src/EnergyPlus/Autosizing/SystemAirFlowSizing.cc

Lines 237 to 238 in f274ccb

} else if (this->zoneEqSizing(this->curZoneEqNum).CoolingAirFlow && !this->zoneEqSizing(this->curZoneEqNum).HeatingAirFlow) {
this->autoSizedValue = this->dataFracOfAutosizedCoolingAirflow * this->zoneEqSizing(this->curZoneEqNum).CoolingAirVolFlow;

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In SystemAirFlowSizing, if CoolingAirVolFlow = windowAC.MaxAirVolFlow (which should be already adjusted?) and dataFracOfAutosizedCoolingAirflow = the target fraction, then how does this get the right answer? I would think this would either be 1 * adjusted air flow or fraction * design air flow. This looks like it's fraction * adjusted air flow. Maybe windowAC.MaxAirVolFlow is the design air flow which gets multiplied by the fraction. In any event you are getting the right answer now.

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Apologies, I linked to the wrong bit in SystemAirFlowSizing. The correct bit is:

EnergyPlus/src/EnergyPlus/Autosizing/SystemAirFlowSizing.cc

Lines 619 to 620 in 54f875d

if (this->zoneEqSizing(this->curZoneEqNum).CoolingAirFlow && !this->zoneEqSizing(this->curZoneEqNum).HeatingAirFlow) {
this->autoSizedValue = this->zoneEqSizing(this->curZoneEqNum).CoolingAirVolFlow; 

Process 2757796 stopped
* thread #1, name = 'energyplus', stop reason = step over
    frame #0: 0x00007ffff50d4370 libenergyplusapi.so.24.2.0`EnergyPlus::SystemAirFlowSizer::size(this=0x00007fffffff4d88, state=0x00007fffffffa980, _originalValue=-99999, errorsFound=0x00007fffffff529f) at SystemAirFlowSizing.cc:620:54
   617 	                    }
   618 	                } else {
   619 	                    if (this->zoneEqSizing(this->curZoneEqNum).CoolingAirFlow && !this->zoneEqSizing(this->curZoneEqNum).HeatingAirFlow) {
-> 620 	                        this->autoSizedValue = this->zoneEqSizing(this->curZoneEqNum).CoolingAirVolFlow;
   621 	                        if (this->finalZoneSizing(this->curZoneEqNum).CoolDDNum > 0 &&
   622 	                            this->finalZoneSizing(this->curZoneEqNum).CoolDDNum <= state.dataEnvrn->TotDesDays) {
   623 	                            DDNameFanPeak = state.dataWeather->DesDayInput(this->finalZoneSizing(this->curZoneEqNum).CoolDDNum).Title;
(lldb) p this->zoneEqSizing(this->curZoneEqNum).CoolingAirVolFlow
(Real64) 0.28246116346780509

}

state.dataSize->DataScalableCapSizingON = false;
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