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Address VS DX cooling coil outlet air condition calculation problem when PLR is zero #8607

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merged 7 commits into from
Mar 16, 2021
Merged

Address VS DX cooling coil outlet air condition calculation problem when PLR is zero #8607

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fab99b3
VS DXCCoil in ContFanCycCoil_ZeroCompPLR Mode
Mar 10, 2021
65ca742
Added unit test
Mar 10, 2021
917d4c6
Address failed UnitarySystem unit test
Mar 10, 2021
629a52a
Unit test cleanup
Mar 10, 2021
ac6f2fd
Merge branch 'develop' into 176972354_Issue8543
Mar 15, 2021
55c3808
Modified unit test to match dataLoopNodes globals
Mar 15, 2021
9b5efd8
Merge branch 'develop' into 176972354_Issue8543
Mar 15, 2021
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26 changes: 14 additions & 12 deletions src/EnergyPlus/VariableSpeedCoils.cc
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Expand Up @@ -5460,19 +5460,21 @@ namespace VariableSpeedCoils {
}
}

// calculate coil outlet state variables
state.dataVariableSpeedCoils->LoadSideOutletEnth = state.dataVariableSpeedCoils->LoadSideInletEnth - state.dataVariableSpeedCoils->QLoadTotal / state.dataVariableSpeedCoils->LoadSideMassFlowRate;
state.dataVariableSpeedCoils->LoadSideOutletDBTemp = state.dataVariableSpeedCoils->LoadSideInletDBTemp - state.dataVariableSpeedCoils->QSensible / (state.dataVariableSpeedCoils->LoadSideMassFlowRate * CpAir);
if ((PartLoadRatio > 0.0 && CyclingScheme == ContFanCycCoil) || (CyclingScheme == CycFanCycCoil)) {
// calculate coil outlet state variables
state.dataVariableSpeedCoils->LoadSideOutletEnth = state.dataVariableSpeedCoils->LoadSideInletEnth - state.dataVariableSpeedCoils->QLoadTotal / state.dataVariableSpeedCoils->LoadSideMassFlowRate;
state.dataVariableSpeedCoils->LoadSideOutletDBTemp = state.dataVariableSpeedCoils->LoadSideInletDBTemp - state.dataVariableSpeedCoils->QSensible / (state.dataVariableSpeedCoils->LoadSideMassFlowRate * CpAir);
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Avoids calculating the VS DX cooling coil when the compressor PLR is zero and the fan operating mode is ContFanCycCoil. Otherwise, allowing it sometimes may result in very cold coil outlet air condition that leads to psychometric error message.


MaxHumRat = PsyWFnTdbRhPb(state, state.dataVariableSpeedCoils->LoadSideOutletDBTemp, 0.9999, state.dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).InletAirPressure, RoutineName);
MaxOutletEnth = PsyHFnTdbW(state.dataVariableSpeedCoils->LoadSideOutletDBTemp, MaxHumRat);
if (state.dataVariableSpeedCoils->LoadSideOutletEnth > MaxOutletEnth) {
state.dataVariableSpeedCoils->LoadSideOutletEnth = MaxOutletEnth;
// QLoadTotal = LoadSideMassFlowRate * (LoadSideInletEnth - LoadSideOutletEnth)
}
state.dataVariableSpeedCoils->LoadSideOutletHumRat = PsyWFnTdbH(state, state.dataVariableSpeedCoils->LoadSideOutletDBTemp, state.dataVariableSpeedCoils->LoadSideOutletEnth, RoutineName);
if (state.dataVariableSpeedCoils->LoadSideOutletHumRat > MaxHumRat) {
state.dataVariableSpeedCoils->LoadSideOutletHumRat = MaxHumRat;
MaxHumRat = PsyWFnTdbRhPb(state, state.dataVariableSpeedCoils->LoadSideOutletDBTemp, 0.9999, state.dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).InletAirPressure, RoutineName);
MaxOutletEnth = PsyHFnTdbW(state.dataVariableSpeedCoils->LoadSideOutletDBTemp, MaxHumRat);
if (state.dataVariableSpeedCoils->LoadSideOutletEnth > MaxOutletEnth) {
state.dataVariableSpeedCoils->LoadSideOutletEnth = MaxOutletEnth;
// QLoadTotal = LoadSideMassFlowRate * (LoadSideInletEnth - LoadSideOutletEnth)
}
state.dataVariableSpeedCoils->LoadSideOutletHumRat = PsyWFnTdbH(state, state.dataVariableSpeedCoils->LoadSideOutletDBTemp, state.dataVariableSpeedCoils->LoadSideOutletEnth, RoutineName);
if (state.dataVariableSpeedCoils->LoadSideOutletHumRat > MaxHumRat) {
state.dataVariableSpeedCoils->LoadSideOutletHumRat = MaxHumRat;
}
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This is part of the same change.

}

++Count;
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3 changes: 3 additions & 0 deletions tst/EnergyPlus/unit/UnitarySystem.unit.cc
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Expand Up @@ -2702,6 +2702,9 @@ TEST_F(ZoneUnitarySysTest, UnitarySystemModel_MultispeedPerformance)
bool const ZoneEquipment = true;
Real64 sensOut = 0.0;
Real64 latOut = 0.0;

// this setup is a continuous fan cycling coil op mode
thisSys->m_FanOpMode = DataHVACGlobals::ContFanCycCoil;
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Added this to correct a failing unit test.


thisSys->simulate(*state,
thisSys->Name,
Expand Down
164 changes: 164 additions & 0 deletions tst/EnergyPlus/unit/VariableSpeedCoils.unit.cc
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Expand Up @@ -55,6 +55,9 @@
#include <EnergyPlus/Data/EnergyPlusData.hh>
#include <EnergyPlus/Psychrometrics.hh>
#include <EnergyPlus/VariableSpeedCoils.hh>
#include <EnergyPlus/DataEnvironment.hh>
#include <EnergyPlus/OutputReportPredefined.hh>
#include <EnergyPlus/DataLoopNode.hh>

namespace EnergyPlus {

Expand Down Expand Up @@ -2807,4 +2810,165 @@ TEST_F(EnergyPlusFixture, VariableSpeedCoils_Test_CalcTotCap_VSWSHP)
EXPECT_NEAR(OutletAirRH, 0.999, 0.001);
EXPECT_LT(OutletAirRH, 1.0);
}

TEST_F(EnergyPlusFixture, VariableSpeedCoils_ContFanCycCoil_Test)
{
std::string const idf_objects = delimited_string({
" Coil:Cooling:DX:VariableSpeed,",
" VS DXCOIL, !- Name",
" VS DXCOIL_CoolCNode, !- Air Inlet Node Name",
" VS DXCOIL_HeatCNode, !- Air Outlet Node Name",
" 5, !- Number of Speeds {dimensionless}",
" 5, !- Nominal Speed Level {dimensionless}",
" 135000.0, !- Rated Total Cooling Capacity At Selected Nominal Speed Level {w}",
" 5.00, !- Rated Volumetric Air Flow Rate At Selected Nominal Speed Level {m3/s}",
" 0, !- Nominal Time for Condensate to Begin Leaving the Coil {s}",
" 0, !- Initial Moisture Evaporation Rate Divided by Steady-State AC Latent Capacity {dimensionless}",
" PLF Curve, !- Energy Part Load Fraction Curve Name",
" , !- Condenser Air Inlet Node Name",
" AirCooled, !- Condenser Type",
" , !- Evaporative Condenser Pump Rated Power Consumption {W}",
" , !- Crankcase Heater Capacity {W}",
" 10, !- Maximum Outdoor Dry-Bulb Temperature for Crankcase Heater Operation {C}",
" , !- Minimum Outdoor Dry-Bulb Temperature for Compressor Operation {C}",
" , !- Supply Water Storage Tank Name",
" , !- Condensate Collection Water Storage Tank Name",
" , !- Basin Heater Capacity {W/K}",
" 2, !- Basin Heater Setpoint Temperature {C}",
" , !- Basin Heater Operating Schedule Name",
" 33000.0, !- Speed 1 Reference Unit Total Cooling Capacity At Rated Conditions {w}",
" 0.70, !- Speed 1 Reference Unit Sensible Heat Ratio At Rated Conditions {dimensionless}",
" 4.34, !- Speed 1 Reference Unit COP At Rated Conditions {dimensionless}",
" 1.40, !- Speed 1 Reference Unit Air Flow Rate At Rated Conditions {m3/s}",
" 4.03, !- Speed 1 Reference Unit Condenser Flow Rate at Rated Conditions {m3/s}",
" , !- Speed 1 Reference Unit Pad Effectiveness of Evap Precooling at Rated Conditions {dimensionless}",
" CapacityCurve, !- Speed 1 Total Cooling Capacity Function of Temperature Curve Name",
" CAPFF Curve, !- Speed 1 Total Cooling Capacity Function of Air Flow Fraction Curve Name",
" PowerCurve, !- Speed 1 Energy Input Ratio Function of Temperature Curve Name",
" EIRFF Curve, !- Speed 1 Energy Input Ratio Function of Air Flow Fraction Curve Name",
" 35000.0, !- Speed 2 Reference Unit Total Cooling Capacity At Rated Conditions {w}",
" 0.78, !- Speed 2 Reference Unit Sensible Heat Ratio At Rated Conditions {dimensionless}",
" 4.54, !- Speed 2 Reference Unit COP At Rated Conditions {dimensionless}",
" 1.90, !- Speed 2 Reference Unit Air Flow Rate At Rated Conditions {m3/s}",
" 5.47, !- Speed 2 Reference Unit Condenser Flow Rate at Rated Conditions {m3/s}",
" , !- Speed 2 Reference Unit Pad Effectiveness of Evap Precooling at Rated Conditions {dimensionless}",
" CapacityCurve, !- Speed 2 Total Cooling Capacity Function of Temperature Curve Name",
" CAPFF Curve, !- Speed 2 Total Cooling Capacity Function of Air Flow Fraction Curve Name",
" PowerCurve, !- Speed 2 Energy Input Ratio Function of Temperature Curve Name",
" EIRFF Curve, !- Speed 2 Energy Input Ratio Function of Air Flow Fraction Curve Name",
" 70000.0, !- Speed 3 Reference Unit Total Cooling Capacity At Rated Conditions {w}",
" 0.70, !- Speed 3 Reference Unit Sensible Heat Ratio At Rated Conditions {dimensionless}",
" 4.20, !- Speed 3 Reference Unit COP At Rated Conditions {dimensionless}",
" 2.89, !- Speed 3 Reference Unit Air Flow Rate At Rated Conditions {m3/s}",
" 8.26, !- Speed 3 Reference Unit Condenser Flow Rate at Rated Conditions {m3/s}",
" , !- Speed 3 Reference Unit Pad Effectiveness of Evap Precooling at Rated Conditions {dimensionless}",
" CapacityCurve, !- Speed 3 Total Cooling Capacity Function of Temperature Curve Name",
" CAPFF Curve, !- Speed 3 Total Cooling Capacity Function of Air Flow Fraction Curve Name",
" PowerCurve, !- Speed 3 Energy Input Ratio Function of Temperature Curve Name",
" EIRFF Curve, !- Speed 3 Energy Input Ratio Function of Air Flow Fraction Curve Name",
" 120000.0, !- Speed 4 Reference Unit Total Cooling Capacity At Rated Conditions {w}",
" 0.62, !- Speed 4 Reference Unit Sensible Heat Ratio At Rated Conditions {dimensionless}",
" 3.47, !- Speed 4 Reference Unit COP At Rated Conditions {dimensionless}",
" 3.56, !- Speed 4 Reference Unit Air Flow Rate At Rated Conditions {m3/s}",
" 10.25, !- Speed 4 Reference Unit Condenser Flow Rate at Rated Conditions {m3/s}",
" , !- Speed 4 Reference Unit Pad Effectiveness of Evap Precooling at Rated Conditions {dimensionless}",
" CapacityCurve, !- Speed 4 Total Cooling Capacity Function of Temperature Curve Name",
" CAPFF Curve, !- Speed 4 Total Cooling Capacity Function of Air Flow Fraction Curve Name",
" PowerCurve, !- Speed 4 Energy Input Ratio Function of Temperature Curve Name",
" EIRFF Curve, !- Speed 4 Energy Input Ratio Function of Air Flow Fraction Curve Name",
" 140000.0, !- Speed 5 Reference Unit Total Cooling Capacity At Rated Conditions {w}",
" 0.69, !- Speed 5 Reference Unit Sensible Heat Ratio At Rated Conditions {dimensionless}",
" 3.84, !- Speed 5 Reference Unit COP At Rated Conditions {dimensionless}",
" 5.68, !- Speed 5 Reference Unit Air Flow Rate At Rated Conditions {m3/s}",
" 16.36, !- Speed 5 Reference Unit Condenser Flow Rate at Rated Conditions {m3/s}",
" , !- Speed 5 Reference Unit Pad Effectiveness of Evap Precooling at Rated Conditions {dimensionless}",
" CapacityCurve, !- Speed 5 Total Cooling Capacity Function of Temperature Curve Name",
" CAPFF Curve, !- Speed 5 Total Cooling Capacity Function of Air Flow Fraction Curve Name",
" PowerCurve, !- Speed 5 Energy Input Ratio Function of Temperature Curve Name",
" EIRFF Curve; !- Speed 5 Energy Input Ratio Function of Air Flow Fraction Curve Name",

"Curve:Biquadratic,",
" CapacityCurve, 1, 0, 0, 0, 0, 0, 10, 25.5, 7.2, 48.8, , , Temperature, Temperature, Dimensionless;",
"Curve:Biquadratic,",
" PowerCurve, 1, 0, 0, 0, 0, 0, 10, 25.5, 7.2, 48.8, , , Temperature, Temperature, Dimensionless;",
"Curve:Cubic,",
" CAPFF Curve, 1, 0, 0, 0, 0, 1, , , Dimensionless, Dimensionless;",
"Curve:Cubic,",
" EIRFF Curve, 1, 0, 0, 0, 0, 1, , , Dimensionless, Dimensionless;",
"Curve:Quadratic,",
" PLF Curve, 0.85, 0.8333, 0.0, 0.0, 0.3, 0.85, 1.0, Dimensionless, Dimensionless;",

});

ASSERT_TRUE(process_idf(idf_objects));
// get coil inputs
VariableSpeedCoils::GetVarSpeedCoilInput(*state);
// Setting predefined tables is needed though
OutputReportPredefined::SetPredefinedTables(*state);
// Set up some environmental parameters
state->dataEnvrn->OutDryBulbTemp = 5.0;
state->dataEnvrn->OutHumRat = 0.0009;
state->dataEnvrn->OutBaroPress = 99000.0;
state->dataEnvrn->WindSpeed = 5.0;
state->dataEnvrn->WindDir = 270.0;
// set coil parameters
int const CyclingScheme = DataHVACGlobals::ContFanCycCoil;
int DXCoilNum = 1;
int CompOp = 0;
int const SpeedCal = 1;
Real64 RuntimeFrac = 1.0;
Real64 SensLoad = 0.0;
Real64 LatentLoad = 0.0;
Real64 PartLoadFrac = 0.0;
Real64 OnOffAirFlowRatio = 1.0;
Real64 SpeedRatio = 0.0;
Real64 MaxONOFFCyclesperHour(0.0);
Real64 HPTimeConstant(0.0);
Real64 FanDelayTime(0.0);

// run coil init
VariableSpeedCoils::InitVarSpeedCoil(
*state, DXCoilNum, MaxONOFFCyclesperHour, HPTimeConstant, FanDelayTime, SensLoad, LatentLoad, CyclingScheme, OnOffAirFlowRatio, SpeedRatio, SpeedCal);
// set coil inlet condition
state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).InletAirDBTemp = 24.0;
state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).InletAirHumRat = 0.009;
state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).InletAirEnthalpy = Psychrometrics::PsyHFnTdbW(24.0, 0.009);
// test 1: compressor is On but PLR = 0
CompOp = 1;
PartLoadFrac = 0.0;
// set coil inlet air flow rate to speed 1
state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).AirMassFlowRate =
state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).MSRatedAirMassFlowRate(1) * 0.1;
state->dataVariableSpeedCoils->LoadSideMassFlowRate = state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).AirMassFlowRate;
DataLoopNode::Node(state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).AirInletNodeNum).MassFlowRate =
state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).AirMassFlowRate;
VariableSpeedCoils::CalcVarSpeedCoilCooling(
*state, DXCoilNum, CyclingScheme, RuntimeFrac, SensLoad, LatentLoad, CompOp, PartLoadFrac, OnOffAirFlowRatio, SpeedRatio, SpeedCal);
;
// check coil outlet and inlet air conditions match
EXPECT_EQ(state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).OutletAirDBTemp, state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).InletAirDBTemp);
EXPECT_EQ(state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).OutletAirHumRat, state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).InletAirHumRat);
EXPECT_EQ(state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).OutletAirEnthalpy, state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).InletAirEnthalpy);
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This shows the coil outlet node air condition matches that of the inlet air condition when the PLR is zero.

;
// test 2: compressor is On and PLR > 0
CompOp = 1;
PartLoadFrac = 0.1;
// set coil inlet condition
state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).InletAirDBTemp = 24.0;
state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).InletAirHumRat = 0.009;
state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).InletAirEnthalpy = Psychrometrics::PsyHFnTdbW(24.0, 0.009);
// set coil inlet air flow rate to speed 1 times PLR
state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).AirMassFlowRate =
state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).MSRatedAirMassFlowRate(1) * PartLoadFrac;
state->dataVariableSpeedCoils->LoadSideMassFlowRate = state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).AirMassFlowRate;
DataLoopNode::Node(state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).AirInletNodeNum).MassFlowRate =
state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).AirMassFlowRate;
// run the coil
VariableSpeedCoils::CalcVarSpeedCoilCooling(
*state, DXCoilNum, CyclingScheme, RuntimeFrac, SensLoad, LatentLoad, CompOp, PartLoadFrac, OnOffAirFlowRatio, SpeedRatio, SpeedCal);
// check coil air outlet conditions
EXPECT_NEAR(state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).OutletAirDBTemp, 5.79484, 0.00001);
EXPECT_NEAR(state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).OutletAirHumRat, 0.00810, 0.00001);
EXPECT_NEAR(state->dataVariableSpeedCoils->VarSpeedCoil(DXCoilNum).OutletAirEnthalpy, 26170.26, 0.01);
}
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New unit test.

} // namespace EnergyPlus