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Merge pull request #10582 from NREL/adjust-mixed-air-temp
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Adjust mixed air temp
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@Myoldmopar
Myoldmopar authored Jul 25, 2024
2 parents e85c6ac + abed1f0 commit ef02672
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Showing 4 changed files with 210 additions and 164 deletions.
139 changes: 70 additions & 69 deletions src/EnergyPlus/MixedAir.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -758,11 +758,13 @@ void SimOAMixer(EnergyPlusData &state, std::string const &CompName, int &CompInd
OAMixerNum = CompIndex;
}

InitOAMixer(state, OAMixerNum);
auto &mixer = state.dataMixedAir->OAMixer(OAMixerNum);

CalcOAMixer(state, OAMixerNum);
mixer.InitOAMixer(state);

UpdateOAMixer(state, OAMixerNum);
mixer.CalcOAMixer(state);

mixer.UpdateOAMixer(state);
}

void SimOAController(EnergyPlusData &state, std::string const &CtrlName, int &CtrlIndex, bool const FirstHVACIteration, int const AirLoopNum)
Expand Down Expand Up @@ -3291,7 +3293,7 @@ void InitOAController(EnergyPlusData &state, int const OAControllerNum, bool con
}
} // namespace MixedAir

void InitOAMixer(EnergyPlusData &state, int const OAMixerNum)
void OAMixerProps::InitOAMixer(EnergyPlusData &state)
{
// SUBROUTINE INFORMATION:
// AUTHOR Fred Buhl
Expand All @@ -3300,24 +3302,24 @@ void InitOAMixer(EnergyPlusData &state, int const OAMixerNum)
// PURPOSE OF THIS SUBROUTINE
// Initialize the OAMixer data structure with input node data

int RetNode = state.dataMixedAir->OAMixer(OAMixerNum).RetNode;
int InletNode = state.dataMixedAir->OAMixer(OAMixerNum).InletNode;
int RelNode = state.dataMixedAir->OAMixer(OAMixerNum).RelNode;
int RetNode = this->RetNode;
int InletNode = this->InletNode;
int RelNode = this->RelNode;

// Return air stream data
state.dataMixedAir->OAMixer(OAMixerNum).RetTemp = state.dataLoopNodes->Node(RetNode).Temp;
state.dataMixedAir->OAMixer(OAMixerNum).RetHumRat = state.dataLoopNodes->Node(RetNode).HumRat;
state.dataMixedAir->OAMixer(OAMixerNum).RetEnthalpy = state.dataLoopNodes->Node(RetNode).Enthalpy;
state.dataMixedAir->OAMixer(OAMixerNum).RetPressure = state.dataLoopNodes->Node(RetNode).Press;
state.dataMixedAir->OAMixer(OAMixerNum).RetMassFlowRate = state.dataLoopNodes->Node(RetNode).MassFlowRate;
this->RetTemp = state.dataLoopNodes->Node(RetNode).Temp;
this->RetHumRat = state.dataLoopNodes->Node(RetNode).HumRat;
this->RetEnthalpy = state.dataLoopNodes->Node(RetNode).Enthalpy;
this->RetPressure = state.dataLoopNodes->Node(RetNode).Press;
this->RetMassFlowRate = state.dataLoopNodes->Node(RetNode).MassFlowRate;
// Outside air stream data
state.dataMixedAir->OAMixer(OAMixerNum).OATemp = state.dataLoopNodes->Node(InletNode).Temp;
state.dataMixedAir->OAMixer(OAMixerNum).OAHumRat = state.dataLoopNodes->Node(InletNode).HumRat;
state.dataMixedAir->OAMixer(OAMixerNum).OAEnthalpy = state.dataLoopNodes->Node(InletNode).Enthalpy;
state.dataMixedAir->OAMixer(OAMixerNum).OAPressure = state.dataLoopNodes->Node(InletNode).Press;
state.dataMixedAir->OAMixer(OAMixerNum).OAMassFlowRate = state.dataLoopNodes->Node(InletNode).MassFlowRate;
this->OATemp = state.dataLoopNodes->Node(InletNode).Temp;
this->OAHumRat = state.dataLoopNodes->Node(InletNode).HumRat;
this->OAEnthalpy = state.dataLoopNodes->Node(InletNode).Enthalpy;
this->OAPressure = state.dataLoopNodes->Node(InletNode).Press;
this->OAMassFlowRate = state.dataLoopNodes->Node(InletNode).MassFlowRate;
// Relief air data
state.dataMixedAir->OAMixer(OAMixerNum).RelMassFlowRate = state.dataLoopNodes->Node(RelNode).MassFlowRate;
this->RelMassFlowRate = state.dataLoopNodes->Node(RelNode).MassFlowRate;
}

void OAControllerProps::CalcOAController(EnergyPlusData &state, int const AirLoopNum, bool const FirstHVACIteration)
Expand Down Expand Up @@ -4630,7 +4632,8 @@ void OAControllerProps::CalcOAEconomizer(EnergyPlusData &state,
this->HighHumCtrlActive = false;
}
}
void CalcOAMixer(EnergyPlusData &state, int const OAMixerNum)

void OAMixerProps::CalcOAMixer(EnergyPlusData &state)
{

// SUBROUTINE INFORMATION:
Expand All @@ -4641,48 +4644,46 @@ void CalcOAMixer(EnergyPlusData &state, int const OAMixerNum)
// Calculate the mixed air flow and conditions

// Define a recirculation mass flow rate
Real64 RecircMassFlowRate = state.dataMixedAir->OAMixer(OAMixerNum).RetMassFlowRate - state.dataMixedAir->OAMixer(OAMixerNum).RelMassFlowRate;
Real64 RecircMassFlowRate = this->RetMassFlowRate - this->RelMassFlowRate;
// In certain low flow conditions the return air mass flow rate can be below the outside air value established
// by the user. This check will ensure that this condition does not result in unphysical air properties.
if (RecircMassFlowRate < 0.0) {
RecircMassFlowRate = 0.0;
state.dataMixedAir->OAMixer(OAMixerNum).RelMassFlowRate = state.dataMixedAir->OAMixer(OAMixerNum).RetMassFlowRate;
this->RelMassFlowRate = this->RetMassFlowRate;
}

// Pass through the return air conditions to the relief air stream. The return air is "split" to
// the relief air and the recirculation air.
state.dataMixedAir->OAMixer(OAMixerNum).RelTemp = state.dataMixedAir->OAMixer(OAMixerNum).RetTemp;
state.dataMixedAir->OAMixer(OAMixerNum).RelHumRat = state.dataMixedAir->OAMixer(OAMixerNum).RetHumRat;
state.dataMixedAir->OAMixer(OAMixerNum).RelEnthalpy = state.dataMixedAir->OAMixer(OAMixerNum).RetEnthalpy;
state.dataMixedAir->OAMixer(OAMixerNum).RelPressure = state.dataMixedAir->OAMixer(OAMixerNum).RetPressure;
Real64 RecircPressure = state.dataMixedAir->OAMixer(OAMixerNum).RetPressure;
Real64 RecircEnthalpy = state.dataMixedAir->OAMixer(OAMixerNum).RetEnthalpy;
Real64 RecircHumRat = state.dataMixedAir->OAMixer(OAMixerNum).RetHumRat;
this->RelTemp = this->RetTemp;
this->RelHumRat = this->RetHumRat;
this->RelEnthalpy = this->RetEnthalpy;
this->RelPressure = this->RetPressure;
Real64 RecircPressure = this->RetPressure;
Real64 RecircEnthalpy = this->RetEnthalpy;
Real64 RecircHumRat = this->RetHumRat;
// The recirculation air and the outside air are mixed to form the mixed air stream
state.dataMixedAir->OAMixer(OAMixerNum).MixMassFlowRate = state.dataMixedAir->OAMixer(OAMixerNum).OAMassFlowRate + RecircMassFlowRate;
this->MixMassFlowRate = this->OAMassFlowRate + RecircMassFlowRate;
// Check for zero flow
if (state.dataMixedAir->OAMixer(OAMixerNum).MixMassFlowRate <= HVAC::VerySmallMassFlow) {
state.dataMixedAir->OAMixer(OAMixerNum).MixEnthalpy = state.dataMixedAir->OAMixer(OAMixerNum).RetEnthalpy;
state.dataMixedAir->OAMixer(OAMixerNum).MixHumRat = state.dataMixedAir->OAMixer(OAMixerNum).RetHumRat;
state.dataMixedAir->OAMixer(OAMixerNum).MixPressure = state.dataMixedAir->OAMixer(OAMixerNum).RetPressure;
state.dataMixedAir->OAMixer(OAMixerNum).MixTemp = state.dataMixedAir->OAMixer(OAMixerNum).RetTemp;
if (this->MixMassFlowRate <= HVAC::VerySmallMassFlow) {
this->MixEnthalpy = this->RetEnthalpy;
this->MixHumRat = this->RetHumRat;
this->MixPressure = this->RetPressure;
this->MixTemp = this->RetTemp;
return;
}

state.dataMixedAir->OAMixer(OAMixerNum).MixEnthalpy =
(RecircMassFlowRate * RecircEnthalpy +
state.dataMixedAir->OAMixer(OAMixerNum).OAMassFlowRate * state.dataMixedAir->OAMixer(OAMixerNum).OAEnthalpy) /
state.dataMixedAir->OAMixer(OAMixerNum).MixMassFlowRate;
state.dataMixedAir->OAMixer(OAMixerNum).MixHumRat = (RecircMassFlowRate * RecircHumRat + state.dataMixedAir->OAMixer(OAMixerNum).OAMassFlowRate *
state.dataMixedAir->OAMixer(OAMixerNum).OAHumRat) /
state.dataMixedAir->OAMixer(OAMixerNum).MixMassFlowRate;
state.dataMixedAir->OAMixer(OAMixerNum).MixPressure =
(RecircMassFlowRate * RecircPressure +
state.dataMixedAir->OAMixer(OAMixerNum).OAMassFlowRate * state.dataMixedAir->OAMixer(OAMixerNum).OAPressure) /
state.dataMixedAir->OAMixer(OAMixerNum).MixMassFlowRate;
this->MixEnthalpy = (RecircMassFlowRate * RecircEnthalpy + this->OAMassFlowRate * this->OAEnthalpy) / this->MixMassFlowRate;
this->MixHumRat = (RecircMassFlowRate * RecircHumRat + this->OAMassFlowRate * this->OAHumRat) / this->MixMassFlowRate;
this->MixPressure = (RecircMassFlowRate * RecircPressure + this->OAMassFlowRate * this->OAPressure) / this->MixMassFlowRate;
// Mixed air temperature is calculated from the mixed air enthalpy and humidity ratio.
state.dataMixedAir->OAMixer(OAMixerNum).MixTemp =
Psychrometrics::PsyTdbFnHW(state.dataMixedAir->OAMixer(OAMixerNum).MixEnthalpy, state.dataMixedAir->OAMixer(OAMixerNum).MixHumRat);
this->MixTemp = Psychrometrics::PsyTdbFnHW(this->MixEnthalpy, this->MixHumRat);

// Check for saturation temperature > dry-bulb temperature and modify temperature at constant enthalpy
Real64 T_sat = Psychrometrics::PsyTsatFnHPb(state, this->MixEnthalpy, this->MixPressure);
if (this->MixTemp < T_sat) {
this->MixTemp = T_sat;
this->MixHumRat = Psychrometrics::PsyWFnTdbH(state, T_sat, this->MixEnthalpy);
}
}

// End of Calculation/Simulation Section of the Module
Expand Down Expand Up @@ -4871,7 +4872,7 @@ void OAControllerProps::UpdateOAController(EnergyPlusData &state)
}
}

void UpdateOAMixer(EnergyPlusData &state, int const OAMixerNum)
void OAMixerProps::UpdateOAMixer(EnergyPlusData &state) const
{

// SUBROUTINE INFORMATION:
Expand All @@ -4882,47 +4883,47 @@ void UpdateOAMixer(EnergyPlusData &state, int const OAMixerNum)
// Move the results of CalcOAMixer to the affected nodes

// SUBROUTINE LOCAL VARIABLE DECLARATIONS:
int MixNode = state.dataMixedAir->OAMixer(OAMixerNum).MixNode;
int RelNode = state.dataMixedAir->OAMixer(OAMixerNum).RelNode;
int RetNode = state.dataMixedAir->OAMixer(OAMixerNum).RetNode;
int MixNode = this->MixNode;
int RelNode = this->RelNode;
int RetNode = this->RetNode;
// Move mixed air data to the mixed air node
state.dataLoopNodes->Node(MixNode).MassFlowRate = state.dataMixedAir->OAMixer(OAMixerNum).MixMassFlowRate;
state.dataLoopNodes->Node(MixNode).Temp = state.dataMixedAir->OAMixer(OAMixerNum).MixTemp;
state.dataLoopNodes->Node(MixNode).HumRat = state.dataMixedAir->OAMixer(OAMixerNum).MixHumRat;
state.dataLoopNodes->Node(MixNode).Enthalpy = state.dataMixedAir->OAMixer(OAMixerNum).MixEnthalpy;
state.dataLoopNodes->Node(MixNode).Press = state.dataMixedAir->OAMixer(OAMixerNum).MixPressure;
state.dataLoopNodes->Node(MixNode).MassFlowRateMaxAvail = state.dataMixedAir->OAMixer(OAMixerNum).MixMassFlowRate;
state.dataLoopNodes->Node(MixNode).MassFlowRate = this->MixMassFlowRate;
state.dataLoopNodes->Node(MixNode).Temp = this->MixTemp;
state.dataLoopNodes->Node(MixNode).HumRat = this->MixHumRat;
state.dataLoopNodes->Node(MixNode).Enthalpy = this->MixEnthalpy;
state.dataLoopNodes->Node(MixNode).Press = this->MixPressure;
state.dataLoopNodes->Node(MixNode).MassFlowRateMaxAvail = this->MixMassFlowRate;
// Move the relief air data to the relief air node
state.dataLoopNodes->Node(RelNode).MassFlowRate = state.dataMixedAir->OAMixer(OAMixerNum).RelMassFlowRate;
state.dataLoopNodes->Node(RelNode).Temp = state.dataMixedAir->OAMixer(OAMixerNum).RelTemp;
state.dataLoopNodes->Node(RelNode).HumRat = state.dataMixedAir->OAMixer(OAMixerNum).RelHumRat;
state.dataLoopNodes->Node(RelNode).Enthalpy = state.dataMixedAir->OAMixer(OAMixerNum).RelEnthalpy;
state.dataLoopNodes->Node(RelNode).Press = state.dataMixedAir->OAMixer(OAMixerNum).RelPressure;
state.dataLoopNodes->Node(RelNode).MassFlowRateMaxAvail = state.dataMixedAir->OAMixer(OAMixerNum).RelMassFlowRate;
state.dataLoopNodes->Node(RelNode).MassFlowRate = this->RelMassFlowRate;
state.dataLoopNodes->Node(RelNode).Temp = this->RelTemp;
state.dataLoopNodes->Node(RelNode).HumRat = this->RelHumRat;
state.dataLoopNodes->Node(RelNode).Enthalpy = this->RelEnthalpy;
state.dataLoopNodes->Node(RelNode).Press = this->RelPressure;
state.dataLoopNodes->Node(RelNode).MassFlowRateMaxAvail = this->RelMassFlowRate;

if (state.dataContaminantBalance->Contaminant.CO2Simulation) {
state.dataLoopNodes->Node(RelNode).CO2 = state.dataLoopNodes->Node(RetNode).CO2;
if (state.dataMixedAir->OAMixer(OAMixerNum).MixMassFlowRate <= HVAC::VerySmallMassFlow) {
if (this->MixMassFlowRate <= HVAC::VerySmallMassFlow) {
state.dataLoopNodes->Node(MixNode).CO2 = state.dataLoopNodes->Node(RetNode).CO2;
} else {
state.dataLoopNodes->Node(MixNode).CO2 =
((state.dataLoopNodes->Node(RetNode).MassFlowRate - state.dataLoopNodes->Node(RelNode).MassFlowRate) *
state.dataLoopNodes->Node(RetNode).CO2 +
state.dataMixedAir->OAMixer(OAMixerNum).OAMassFlowRate * state.dataContaminantBalance->OutdoorCO2) /
state.dataMixedAir->OAMixer(OAMixerNum).MixMassFlowRate;
this->OAMassFlowRate * state.dataContaminantBalance->OutdoorCO2) /
this->MixMassFlowRate;
}
}

if (state.dataContaminantBalance->Contaminant.GenericContamSimulation) {
state.dataLoopNodes->Node(RelNode).GenContam = state.dataLoopNodes->Node(RetNode).GenContam;
if (state.dataMixedAir->OAMixer(OAMixerNum).MixMassFlowRate <= HVAC::VerySmallMassFlow) {
if (this->MixMassFlowRate <= HVAC::VerySmallMassFlow) {
state.dataLoopNodes->Node(MixNode).GenContam = state.dataLoopNodes->Node(RetNode).GenContam;
} else {
state.dataLoopNodes->Node(MixNode).GenContam =
((state.dataLoopNodes->Node(RetNode).MassFlowRate - state.dataLoopNodes->Node(RelNode).MassFlowRate) *
state.dataLoopNodes->Node(RetNode).GenContam +
state.dataMixedAir->OAMixer(OAMixerNum).OAMassFlowRate * state.dataContaminantBalance->OutdoorGC) /
state.dataMixedAir->OAMixer(OAMixerNum).MixMassFlowRate;
this->OAMassFlowRate * state.dataContaminantBalance->OutdoorGC) /
this->MixMassFlowRate;
}
}
}
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develop (Myoldmopar) - Win64-Windows-10-VisualStudio-16: OK (2856 of 2856 tests passed, 0 test warnings)

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