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Corrected CapFTemp curve index used in multi-speed DX coils for capacity sizing #7626

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Jan 8, 2020
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Corrected CapFTemp curve index used in multi-speed DX coils for capacity sizing #7626

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f2c7275
corrected CapFTemp curve index in multi-speed DX coils
Nov 19, 2019
5816753
Added unit test
Nov 20, 2019
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2 changes: 1 addition & 1 deletion src/EnergyPlus/DXCoils.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -14876,7 +14876,7 @@ namespace DXCoils {
(SELECT_CASE_var == CoilDX_HeatingEmpirical) || (SELECT_CASE_var == CoilDX_CoolingTwoStageWHumControl)) {
CapFTCurveIndex = DXCoil(CoilIndex).CCapFTemp(1);
} else if ((SELECT_CASE_var == CoilDX_MultiSpeedCooling) || (SELECT_CASE_var == CoilDX_MultiSpeedHeating)) {
CapFTCurveIndex = DXCoil(CoilIndex).MSCCapFTemp(1);
CapFTCurveIndex = DXCoil(CoilIndex).MSCCapFTemp(DXCoil(CoilIndex).NumOfSpeeds);
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DX coils use the maximum speed for rated design sizing. Thus the curve index used for rated design capacity adjustment should point to the maximum speed curve, instead of the lowest speed.

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An obvious fix, great.

} else if (SELECT_CASE_var == CoilVRF_Heating) {
CapFTCurveIndex = DXCoil(CoilIndex).CCapFTemp(1);
} else {
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137 changes: 137 additions & 0 deletions tst/EnergyPlus/unit/DXCoils.unit.cc
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Expand Up @@ -3833,4 +3833,141 @@ TEST_F(EnergyPlusFixture, TestMultiSpeedCoolingCoilPartialAutoSizeOutput)
EXPECT_EQ(1.75, DXCoil(1).MSRatedAirVolFlowRate(2));
EXPECT_EQ(0.875, DXCoil(1).MSRatedAirVolFlowRate(1));
}

TEST_F(EnergyPlusFixture, DXCoils_GetDXCoilCapFTCurveIndexTest)
{
using CurveManager::BiQuadratic;
using CurveManager::NumCurves;
using CurveManager::Quadratic;
int DXCoilNum;
int CurveNum;

NumDXCoils = 2;
DXCoil.allocate(NumDXCoils);
DXCoil(1).DXCoilType_Num = CoilDX_MultiSpeedCooling;
DXCoil(1).DXCoilType = "Coil:Cooling:DX:MultiSpeed";
DXCoil(2).DXCoilType_Num = CoilDX_MultiSpeedHeating;
DXCoil(2).DXCoilType = "Coil:Heating:DX:MultiSpeed";


for (DXCoilNum = 1; DXCoilNum <= 2; ++DXCoilNum) {
DXCoil(DXCoilNum).NumOfSpeeds = 2;
DXCoil(DXCoilNum).MSRatedTotCap.allocate(DXCoil(DXCoilNum).NumOfSpeeds);
DXCoil(DXCoilNum).MSCCapFTemp.allocate(DXCoil(DXCoilNum).NumOfSpeeds);
}

NumCurves = 4;
PerfCurve.allocate(NumCurves);

CurveNum = 1;
PerfCurve(CurveNum).Name = "HP_Cool-Cap-fT-SP1";
PerfCurve(CurveNum).CurveType = BiQuadratic;
PerfCurve(CurveNum).ObjectType = "Curve:Biquadratic";
PerfCurve(CurveNum).InterpolationType = EvaluateCurveToLimits;
PerfCurve(CurveNum).Coeff1 = 1.658788451;
PerfCurve(CurveNum).Coeff2 = -0.0834530076;
PerfCurve(CurveNum).Coeff3 = 0.00342409032;
PerfCurve(CurveNum).Coeff4 = 0.0024332436;
PerfCurve(CurveNum).Coeff5 = -4.5036e-005;
PerfCurve(CurveNum).Coeff6 = -0.00053367984;
PerfCurve(CurveNum).Var1Min = 13.88;
PerfCurve(CurveNum).Var1Max = 23.88;
PerfCurve(CurveNum).Var2Min = 18.33;
PerfCurve(CurveNum).Var2Max = 51.66;

CurveNum = 2;
PerfCurve(CurveNum).Name = "HP_Cool-Cap-fT-SP2";
PerfCurve(CurveNum).CurveType = BiQuadratic;
PerfCurve(CurveNum).ObjectType = "Curve:Biquadratic";
PerfCurve(CurveNum).InterpolationType = EvaluateCurveToLimits;
PerfCurve(CurveNum).Coeff1 = 1.472738138;
PerfCurve(CurveNum).Coeff2 = -0.0672218352;
PerfCurve(CurveNum).Coeff3 = 0.0029199042;
PerfCurve(CurveNum).Coeff4 = 5.16005999999982e-005;
PerfCurve(CurveNum).Coeff5 = -2.97756e-005;
PerfCurve(CurveNum).Coeff6 = -0.00035908596;
PerfCurve(CurveNum).Var1Min = 13.88;
PerfCurve(CurveNum).Var1Max = 23.88;
PerfCurve(CurveNum).Var2Min = 18.33;
PerfCurve(CurveNum).Var2Max = 51.66;

CurveNum = 3;
PerfCurve(CurveNum).Name = "HP_Heat-Cap-fT-SP1";
PerfCurve(CurveNum).CurveType = BiQuadratic;
PerfCurve(CurveNum).ObjectType = "Curve:Biquadratic";
PerfCurve(CurveNum).InterpolationType = EvaluateCurveToLimits;
PerfCurve(CurveNum).Coeff1 = 0.84077409;
PerfCurve(CurveNum).Coeff2 = -0.0014336586;
PerfCurve(CurveNum).Coeff3 = -0.000150336;
PerfCurve(CurveNum).Coeff4 = 0.029628603;
PerfCurve(CurveNum).Coeff5 = 0.000161676;
PerfCurve(CurveNum).Coeff6 = -2.349e-005;
PerfCurve(CurveNum).Var1Min = -100.0;
PerfCurve(CurveNum).Var1Max = 100.0;
PerfCurve(CurveNum).Var2Min = -100.0;
PerfCurve(CurveNum).Var2Max = 100.0;

CurveNum = 4;
PerfCurve(CurveNum).Name = "HP_Heat-Cap-fT-SP2";
PerfCurve(CurveNum).CurveType = BiQuadratic;
PerfCurve(CurveNum).ObjectType = "Curve:Biquadratic";
PerfCurve(CurveNum).InterpolationType = EvaluateCurveToLimits;
PerfCurve(CurveNum).Coeff1 = 0.831506971;
PerfCurve(CurveNum).Coeff2 = 0.0018392166;
PerfCurve(CurveNum).Coeff3 = -0.000187596;
PerfCurve(CurveNum).Coeff4 = 0.0266002056;
PerfCurve(CurveNum).Coeff5 = 0.000191484;
PerfCurve(CurveNum).Coeff6 = -6.5772e-005;
PerfCurve(CurveNum).Var1Min = -100.0;
PerfCurve(CurveNum).Var1Max = 100.0;
PerfCurve(CurveNum).Var2Min = -100.0;
PerfCurve(CurveNum).Var2Max = 100.0;

DXCoil(1).MSCCapFTemp(1) = 1;
DXCoil(1).MSCCapFTemp(2) = 2;

DXCoilNum = 2;
DXCoil(DXCoilNum).MSCCapFTemp(1) = 3;
DXCoil(DXCoilNum).MSCCapFTemp(2) = 4;

bool ErrorsFound;
int DataTotCapCurveIndex = 0;

DXCoils::GetCoilsInputFlag = false;

// dx cooling coil
int CoilIndex = 1;
EXPECT_EQ(DXCoil(CoilIndex).DXCoilType, "Coil:Cooling:DX:MultiSpeed");
DataTotCapCurveIndex = DXCoils::GetDXCoilCapFTCurveIndex( CoilIndex, ErrorsFound );
EXPECT_EQ(2, DataTotCapCurveIndex);
// evaluate dx cooling coil curves to show impacts of incorrect curve index
Real64 TotCapTempModFac_lowestSpeed = CurveValue(1, 19.4, 30.0);
Real64 TotCapTempModFac_designSpeed = CurveValue(DataTotCapCurveIndex, 19.4, 30.0);
EXPECT_DOUBLE_EQ(1.0503539775151995, TotCapTempModFac_lowestSpeed);
EXPECT_DOUBLE_EQ(1.0333316291120003, TotCapTempModFac_designSpeed);
// apply dx cooling coil capacity curve correction
Real64 PeakCoilCoolingLoad = 10000.0;
Real64 NominalCoolingDesignCapacity_lowestSpeed = PeakCoilCoolingLoad / TotCapTempModFac_lowestSpeed;
Real64 NominalCoolingDesignCapacity_designSpeed = PeakCoilCoolingLoad / TotCapTempModFac_designSpeed;
EXPECT_DOUBLE_EQ(9520.5999254239905, NominalCoolingDesignCapacity_lowestSpeed);
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Unit test that exercises the results. Awesome.

EXPECT_DOUBLE_EQ(9677.4353153145621, NominalCoolingDesignCapacity_designSpeed);

// dx heating coil
CoilIndex = 2;
EXPECT_EQ(DXCoil(CoilIndex).DXCoilType, "Coil:Heating:DX:MultiSpeed");
DataTotCapCurveIndex = DXCoils::GetDXCoilCapFTCurveIndex( CoilIndex, ErrorsFound );
EXPECT_EQ(4, DataTotCapCurveIndex);
// evaluate dx heating coil curves to show impacts of incorrect curve index
TotCapTempModFac_lowestSpeed = CurveValue(3, 5.0, 10.0);
TotCapTempModFac_designSpeed = CurveValue(DataTotCapCurveIndex, 5.0, 10.0);
EXPECT_DOUBLE_EQ(1.1411265269999999, TotCapTempModFac_lowestSpeed);
EXPECT_DOUBLE_EQ(1.1178750099999999, TotCapTempModFac_designSpeed);
// apply dx heating coil capacity curve correction
Real64 PeakCoilHeatingLoad = 10000.0;
Real64 NominalHeatingDesignCapacity_lowestSpeed = PeakCoilHeatingLoad / TotCapTempModFac_lowestSpeed;
Real64 NominalHeatingDesignCapacity_designSpeed = PeakCoilHeatingLoad / TotCapTempModFac_designSpeed;
EXPECT_DOUBLE_EQ(8763.2701224550547, NominalHeatingDesignCapacity_lowestSpeed);
EXPECT_DOUBLE_EQ(8945.5439208717980, NominalHeatingDesignCapacity_designSpeed);
}

} // namespace EnergyPlus