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Fix #7648 - VRF model EIR heat recovery term uses capacity instead of EIR #7723

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Jan 28, 2020
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Fix #7648 - VRF model EIR heat recovery term uses capacity instead of EIR #7723

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8ea3871
Add unit test for #7648 (and modify comments in an existing one, whic…
jmarrec Jan 28, 2020
ae50d96
Adjust / extend test, and _annotate_ it
jmarrec Jan 28, 2020
454365a
Fix #7648
jmarrec Jan 28, 2020
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6 changes: 3 additions & 3 deletions src/EnergyPlus/HVACVariableRefrigerantFlow.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -973,7 +973,7 @@ namespace HVACVariableRefrigerantFlow {
HREIRFT = VRF(VRFCond).HREIRFTCool; // Index to cool EIR as a function of temperature curve for heat recovery
if (HREIRFT > 0) {
// VRF(VRFCond)%HREIRFTCoolConst = 1.1d0 ! initialized to 1.1
if (CurveManager::PerfCurve(VRF(VRFCond).HREIRFTCool).NumDims == 2) { // Curve type for HRCAPFTCool
if (CurveManager::PerfCurve(VRF(VRFCond).HREIRFTCool).NumDims == 2) { // Curve type for HREIRFTCool
VRF(VRFCond).HREIRFTCoolConst = CurveValue(HREIRFT, InletAirWetBulbC, CondInletTemp);
} else {
VRF(VRFCond).HREIRFTCoolConst = CurveValue(HREIRFT, VRF(VRFCond).VRFCondPLR);
Expand Down Expand Up @@ -1015,7 +1015,7 @@ namespace HVACVariableRefrigerantFlow {
HREIRFT = VRF(VRFCond).HREIRFTHeat; // Index to cool EIR as a function of temperature curve for heat recovery
if (HREIRFT > 0) {
// VRF(VRFCond)%HREIRFTCoolConst = 1.1d0 ! initialized to 1.1
if (CurveManager::PerfCurve(VRF(VRFCond).HREIRFTHeat).NumDims == 2) { // Curve type for HRCAPFTHeat
if (CurveManager::PerfCurve(VRF(VRFCond).HREIRFTHeat).NumDims == 2) { // Curve type for HREIRFTHeat
{
auto const SELECT_CASE_var(VRF(VRFCond).HeatingPerformanceOATType);
if (SELECT_CASE_var == DataHVACGlobals::DryBulbIndicator) {
Expand All @@ -1030,7 +1030,7 @@ namespace HVACVariableRefrigerantFlow {
VRF(VRFCond).HREIRFTHeatConst = CurveValue(HREIRFT, VRF(VRFCond).VRFCondPLR);
}
}
HREIRFTConst = VRF(VRFCond).HRCAPFTHeatConst;
HREIRFTConst = VRF(VRFCond).HREIRFTHeatConst;
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Actual fix. I did a few greps to ensure this was the only case where eir was assigned cap or vice versa

HRInitialEIRFrac =
VRF(VRFCond).HRInitialHeatEIRFrac; // Fractional heating degradation at the start of heat recovery from heating mode
HREIRTC = VRF(VRFCond).HRHeatEIRTC; // Time constant used to recover from initial degradation in heating heat recovery
Expand Down
245 changes: 236 additions & 9 deletions tst/EnergyPlus/unit/HVACVariableRefrigerantFlow.unit.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -6020,7 +6020,7 @@ TEST_F(HVACVRFFixture, VRFTest_CondenserCalcTest)
EXPECT_EQ(VRF(VRFCond).ElecCoolingPower, 0.0);

// make adjustment for heat recovery startup degradation
Real64 HREIRFTConst = VRF(VRFCond).HRCAPFTHeatConst;
Real64 HREIRFTConst = VRF(VRFCond).HREIRFTHeatConst;
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This is an existing test. Which will keep working anyways since it doesn't have HR curves

Real64 HRInitialEIRFrac = VRF(VRFCond).HRInitialHeatEIRFrac;
Real64 HREIRAdjustment = HRInitialEIRFrac + (HREIRFTConst - HRInitialEIRFrac) * VRF(VRFCond).SUMultiplier;

Expand Down Expand Up @@ -6063,34 +6063,34 @@ TEST_F(HVACVRFFixture, VRFTest_CondenserCalcTest)

EXPECT_NEAR(VRF(VRFCond).SUMultiplier, 0.86466, 0.00001); // will exponentially rise towards 1.0
EXPECT_EQ(VRF(VRFCond).ElecHeatingPower, VRF(VRFCond).RatedHeatingPower * VRF(VRFCond).VRFCondPLR * HREIRAdjustment);
EXPECT_NEAR(HREIRAdjustment, 1.08646, 0.00001); // will exponentially rise towards VRF( VRFCond ).HRCAPFTHeatConst = 1.1
EXPECT_NEAR(HREIRAdjustment, 1.08646, 0.00001); // will exponentially rise towards VRF( VRFCond ).HREIRFTHeatConst = 1.1

// simulate again and see that power has exponential changed from previous time step
DataGlobals::CurrentTime += DataGlobals::TimeStepZone; // 1.25
CalcVRFCondenser(VRFCond, false);
HREIRAdjustment = HRInitialEIRFrac + (HREIRFTConst - HRInitialEIRFrac) * VRF(VRFCond).SUMultiplier;
EXPECT_NEAR(VRF(VRFCond).SUMultiplier, 0.95021, 0.00001); // will exponentially rise towards 1.0
EXPECT_EQ(VRF(VRFCond).ElecHeatingPower, VRF(VRFCond).RatedHeatingPower * VRF(VRFCond).VRFCondPLR * HREIRAdjustment);
EXPECT_NEAR(HREIRAdjustment, 1.09502, 0.00001); // will exponentially rise towards VRF( VRFCond ).HRCAPFTHeatConst = 1.1
EXPECT_NEAR(HREIRAdjustment, 1.09502, 0.00001); // will exponentially rise towards VRF( VRFCond ).HREIRFTHeatConst = 1.1

// simulate again and see that power has exponential changed from previous time step
DataGlobals::CurrentTime += DataGlobals::TimeStepZone; // 1.5
CalcVRFCondenser(VRFCond, false);
HREIRAdjustment = HRInitialEIRFrac + (HREIRFTConst - HRInitialEIRFrac) * VRF(VRFCond).SUMultiplier;
EXPECT_NEAR(VRF(VRFCond).SUMultiplier, 0.98168, 0.00001); // will exponentially rise towards 1.0
EXPECT_EQ(VRF(VRFCond).ElecHeatingPower, VRF(VRFCond).RatedHeatingPower * VRF(VRFCond).VRFCondPLR * HREIRAdjustment);
EXPECT_NEAR(HREIRAdjustment, 1.09817, 0.00001); // will exponentially rise towards VRF( VRFCond ).HRCAPFTHeatConst = 1.1
EXPECT_NEAR(HREIRAdjustment, 1.09817, 0.00001); // will exponentially rise towards VRF( VRFCond ).HREIRFTHeatConst = 1.1

// simulate again and see that power has exponential changed from previous time step
DataGlobals::CurrentTime += DataGlobals::TimeStepZone; // 1.75
CalcVRFCondenser(VRFCond, false);
HREIRAdjustment = HRInitialEIRFrac + (HREIRFTConst - HRInitialEIRFrac) * VRF(VRFCond).SUMultiplier;
EXPECT_NEAR(VRF(VRFCond).SUMultiplier, 1.0, 0.00001); // will exponentially rise towards 1.0
EXPECT_EQ(VRF(VRFCond).ElecHeatingPower, VRF(VRFCond).RatedHeatingPower * VRF(VRFCond).VRFCondPLR * HREIRAdjustment);
EXPECT_NEAR(HREIRAdjustment, 1.1, 0.00001); // will exponentially rise towards VRF( VRFCond ).HRCAPFTHeatConst = 1.1
EXPECT_NEAR(HREIRAdjustment, 1.1, 0.00001); // will exponentially rise towards VRF( VRFCond ).HREIRFTHeatConst = 1.1

// at end of exponential decay (when SUMultiplier = 1), HREIRAdjustment = VRF( VRFCond ).HRCAPFTHeatConst
EXPECT_EQ(HREIRAdjustment, VRF(VRFCond).HRCAPFTHeatConst);
// at end of exponential decay (when SUMultiplier = 1), HREIRAdjustment = VRF( VRFCond ).HREIRFTHeatConst
EXPECT_EQ(HREIRAdjustment, VRF(VRFCond).HREIRFTHeatConst);
}

TEST_F(HVACVRFFixture, VRFTU_SupplementalHeatingCoilGetInput)
Expand Down Expand Up @@ -10528,7 +10528,7 @@ TEST_F(HVACVRFFixture, VRFTU_SysCurve_ReportOutputVerificationTest)
EXPECT_NEAR(368.1510, thisFan.FanPower, 0.0001);
EXPECT_NEAR(thisDXCoolingCoil.TotalCoolingEnergyRate, (thisVRFTU.TotalCoolingRate + thisFan.FanPower), 0.0001);
}

TEST_F(HVACVRFFixture, VRF_FluidTCtrl_ReportOutputVerificationTest)
{
// PURPOSE OF THIS TEST:
Expand Down Expand Up @@ -12194,7 +12194,7 @@ TEST_F(HVACVRFFixture, VRF_FluidTCtrl_ReportOutputVerificationTest)
Node(thisZoneEquip.ZoneNode).Temp = 24.0;
Node(thisZoneEquip.ZoneNode).HumRat = 0.0075;
Node(thisZoneEquip.ZoneNode).Enthalpy = Psychrometrics::PsyHFnTdbW(Node(thisZoneEquip.ZoneNode).Temp, Node(thisZoneEquip.ZoneNode).HumRat);

auto &thisVRFTU(VRFTU(1));
Node(thisVRFTU.VRFTUInletNodeNum).Temp = 24.0;
Node(thisVRFTU.VRFTUInletNodeNum).HumRat = 0.0075;
Expand Down Expand Up @@ -12239,4 +12239,231 @@ TEST_F(HVACVRFFixture, VRF_FluidTCtrl_ReportOutputVerificationTest)
EXPECT_NEAR(125.2266, thisFan.FanPower, 0.0001);
EXPECT_NEAR(thisDXCoolingCoil.TotalCoolingEnergyRate, (thisVRFTU.TotalCoolingRate + thisFan.FanPower), 0.0001);
}

// Test for #7648: HREIRFTHeat wrongly used HRCAPFTHeatConst. Occurs only if you have Heat Recovery
TEST_F(HVACVRFFixture, VRFTest_CondenserCalcTest_HREIRFTHeat)
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New GTest

{

std::string const idf_objects = delimited_string({

" Curve:Biquadratic,",
" EIRorCapFT, !- Name",
" 1.0, !- Coefficient1 Constant",
" 0, !- Coefficient2 x",
" 0, !- Coefficient3 x**2",
" 0, !- Coefficient4 y",
" 0, !- Coefficient5 y**2",
" 0, !- Coefficient6 x*y",
" -100, !- Minimum Value of x",
" 100, !- Maximum Value of x",
" -100, !- Minimum Value of y",
" 100, !- Maximum Value of y",
" , !- Minimum Curve Output",
" , !- Maximum Curve Output",
" Temperature, !- Input Unit Type for X",
" Temperature, !- Input Unit Type for Y",
" Dimensionless; !- Output Unit Type",

" Curve:Cubic,",
" EIRorCapfPLR, !- Name",
" 0.0, !- Coefficient1 Constant",
" 1.0, !- Coefficient2 x",
" 0.0, !- Coefficient3 x**2",
" 0.0, !- Coefficient4 x**3",
" 0, !- Minimum Value of x",
" 1, !- Maximum Value of x",
" , !- Minimum Curve Output",
" , !- Maximum Curve Output",
" Dimensionless, !- Input Unit Type for X",
" Dimensionless; !- Output Unit Type",

" Curve:Cubic,",
" HRCAPFTHeat, !- Name",
" 0.8, !- Coefficient1 Constant",
" 0.0, !- Coefficient2 x",
" 0.0, !- Coefficient3 x**2",
" 0.0, !- Coefficient4 x**3",
" 0, !- Minimum Value of x",
" 1, !- Maximum Value of x",
" , !- Minimum Curve Output",
" , !- Maximum Curve Output",
" Dimensionless, !- Input Unit Type for X",
" Dimensionless; !- Output Unit Type",

" Curve:Cubic,",
" HREIRFTHeat, !- Name",
" 0.9, !- Coefficient1 Constant",
" 0.0, !- Coefficient2 x",
" 0.0, !- Coefficient3 x**2",
" 0.0, !- Coefficient4 x**3",
" 0, !- Minimum Value of x",
" 1, !- Maximum Value of x",
" , !- Minimum Curve Output",
" , !- Maximum Curve Output",
" Dimensionless, !- Input Unit Type for X",
" Dimensionless; !- Output Unit Type",
});



ASSERT_TRUE(process_idf(idf_objects));
CurveManager::GetCurveInput();

int VRFCond = 1;
VRF.allocate(1);
VRF(VRFCond).CondenserNodeNum = 0;
VRF(VRFCond).CondenserType = 1; // DataHVACGlobals::AirCooled
VRF(VRFCond).ZoneTUListPtr = 1;
VRF(VRFCond).CoolingCapacity = 20000.0;
VRF(VRFCond).HeatingCapacity = 20000.0;
VRF(VRFCond).CoolingCOP = 3.0;
VRF(VRFCond).HeatingCOP = 3.0;
VRF(VRFCond).RatedCoolingPower = VRF(VRFCond).CoolingCapacity / VRF(VRFCond).CoolingCOP;
VRF(VRFCond).RatedHeatingPower = VRF(VRFCond).HeatingCapacity / VRF(VRFCond).HeatingCOP;
VRF(VRFCond).PipingCorrectionCooling = 1.0;
VRF(VRFCond).PipingCorrectionHeating = 1.0;
// Curve Indices, including HR curves (3 & 4)
VRF(VRFCond).CoolCapFT = 1;
VRF(VRFCond).CoolEIRFT = 1;
VRF(VRFCond).CoolEIRFPLR1 = 2;
VRF(VRFCond).HeatEIRFPLR1 = 2;
VRF(VRFCond).HRCAPFTHeat = 3;
VRF(VRFCond).HREIRFTHeat = 4;
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Assigned HR Curves (important). HRCAPFTHeat is a constant 0.8, and HREIRFTHeat is a constant 0.9


CoolCombinationRatio.allocate(1);
CoolCombinationRatio(VRFCond) = 1.0;
HeatCombinationRatio.allocate(1);
HeatCombinationRatio(VRFCond) = 1.0;
LastModeCooling.allocate(1);
LastModeHeating.allocate(1);

TerminalUnitList.allocate(1);
TerminalUnitList(1).NumTUInList = 5;
TerminalUnitList(1).TotalCoolLoad.allocate(5);
TerminalUnitList(1).TotalHeatLoad.allocate(5);
TerminalUnitList(1).ZoneTUPtr.allocate(5);
TerminalUnitList(1).HRCoolRequest.allocate(5);
TerminalUnitList(1).HRHeatRequest.allocate(5);
TerminalUnitList(1).HRCoolRequest = false;
TerminalUnitList(1).HRHeatRequest = false;

TerminalUnitList(1).CoolingCoilAvailable.allocate(5);
TerminalUnitList(1).HeatingCoilAvailable.allocate(5);
// all TU coils are available
TerminalUnitList(1).CoolingCoilAvailable = true;
TerminalUnitList(1).HeatingCoilAvailable = true;

CoolingLoad.allocate(1);
HeatingLoad.allocate(1);

DXCoilCoolInletAirWBTemp.allocate(10);
DXCoilHeatInletAirDBTemp.allocate(10);
DXCoilHeatInletAirWBTemp.allocate(10);

VRFTU.allocate(5);
for (int NumTU = 1; NumTU <= TerminalUnitList(1).NumTUInList; ++NumTU) {
VRFTU(NumTU).CoolCoilIndex = NumTU;
VRFTU(NumTU).HeatCoilIndex = TerminalUnitList(1).NumTUInList + NumTU;
TerminalUnitList(1).ZoneTUPtr(NumTU) = NumTU;
// initialize DX coil inlet conditions
DXCoilCoolInletAirWBTemp(NumTU) = 19.4;
DXCoilHeatInletAirDBTemp(TerminalUnitList(1).NumTUInList + NumTU) = 20.0;
DXCoilHeatInletAirWBTemp(TerminalUnitList(1).NumTUInList + NumTU) = 17.0;
}

// set up environment
DataGlobals::DayOfSim = 1;
DataGlobals::CurrentTime = 0.25;
DataGlobals::TimeStepZone = 0.25;
DataHVACGlobals::TimeStepSys = 0.25;
DataHVACGlobals::SysTimeElapsed = 0.0;
DataEnvironment::OutDryBulbTemp = 35.0;
DataEnvironment::OutHumRat = 0.01;
DataEnvironment::OutBaroPress = 101325.0;
DataEnvironment::OutWetBulbTemp = 21.1340575;

// increment time step
DataGlobals::CurrentTime += DataGlobals::TimeStepZone; // 0.5

// set TU's to request both cooling and heating
CoolingLoad(VRFCond) = false;
HeatingLoad(VRFCond) = true;
LastModeCooling(VRFCond) = false;
LastModeHeating(VRFCond) = true;

TerminalUnitList(1).TotalCoolLoad(1) = 0.0;
TerminalUnitList(1).HRCoolRequest(1) = false;
TerminalUnitList(1).TotalCoolLoad(2) = 1000.0;
TerminalUnitList(1).HRCoolRequest(2) = true;
TerminalUnitList(1).TotalCoolLoad(3) = 0.0;
TerminalUnitList(1).HRCoolRequest(3) = false;
TerminalUnitList(1).TotalCoolLoad(4) = 1000.0;
TerminalUnitList(1).HRCoolRequest(4) = true;
TerminalUnitList(1).TotalCoolLoad(5) = 0.0;
TerminalUnitList(1).HRCoolRequest(5) = false;
TerminalUnitList(1).TotalHeatLoad(1) = 1000.0;
TerminalUnitList(1).HRHeatRequest(1) = true;
TerminalUnitList(1).TotalHeatLoad(2) = 0.0;
TerminalUnitList(1).HRHeatRequest(2) = false;
TerminalUnitList(1).TotalHeatLoad(3) = 1000.0;
TerminalUnitList(1).HRHeatRequest(3) = true;
TerminalUnitList(1).TotalHeatLoad(4) = 0.0;
TerminalUnitList(1).HRHeatRequest(4) = false;
TerminalUnitList(1).TotalHeatLoad(5) = 1000.0;
TerminalUnitList(1).HRHeatRequest(5) = true;
VRF(VRFCond).HeatRecoveryUsed = true;

// set heat recovery time constant to non-zero value (means mode change will degrade performance)
VRF(VRFCond).HRHeatCapTC = 0.25; // 15 min exponential rise
// VRF(VRFCond).HRHeatEIRTC = 0.0; // (default)
// last operating mode was heating
CalcVRFCondenser(VRFCond, false);
EXPECT_TRUE(VRF(VRFCond).ModeChange);
EXPECT_FALSE(VRF(VRFCond).HRModeChange);
EXPECT_EQ(VRF(VRFCond).OperatingMode, 2); // ModeHeatingOnly
EXPECT_TRUE(VRF(VRFCond).HRHeatingActive);
EXPECT_FALSE(VRF(VRFCond).HRCoolingActive);
EXPECT_EQ(VRF(VRFCond).TotalCoolingCapacity, 0.0);
EXPECT_EQ(VRF(VRFCond).TUCoolingLoad, 2000.0);
EXPECT_EQ(VRF(VRFCond).TotalHeatingCapacity, 3000.0);
EXPECT_EQ(VRF(VRFCond).TUHeatingLoad, 3000.0);
EXPECT_NEAR(VRF(VRFCond).VRFCondPLR, 0.1875, 0.00001);
EXPECT_EQ(VRF(VRFCond).VRFCondRTF, 1.0); // unit is not cycling below min PLR

// CurrentEndTime = 0.25
// HRTimer = CurrentEndTimeLast = 0
// HRTime = (CurrentEndTime - HRTimer) = 0.25 - = 0.25
// SUMultiplier = min(1, 1 - exp(-HRTime / HRHeatCapTC)) = 1 - exp(-1) = 0.6321205588285577
EXPECT_NEAR(VRF(VRFCond).SUMultiplier, 0.63212, 0.00001);
EXPECT_EQ(VRF(VRFCond).ElecCoolingPower, 0.0);

// make adjustment for heat recovery startup degradation
// Ensure HREIRFTConst / HRCAPFTHeatConst are assigned the right curve ouput
Real64 HREIRFTConst = VRF(VRFCond).HREIRFTHeatConst;
EXPECT_EQ(HREIRFTConst, 0.9); // It's normal that it works, it's the internal variable that's messed up
EXPECT_EQ(VRF(VRFCond).HRCAPFTHeatConst, 0.8);
Real64 HRInitialEIRFrac = VRF(VRFCond).HRInitialHeatEIRFrac;
EXPECT_EQ(HRInitialEIRFrac, 1.0);
// Internally, it uses a local variable HREIRFTConst, which was wrongly set to HRCAPFTHeatConst = 0.9
Real64 HREIRAdjustment = HRInitialEIRFrac + (HREIRFTConst - HRInitialEIRFrac) * VRF(VRFCond).SUMultiplier;
// Before fix, =1 + (0.8 - 1) * 0.63212 = 0.873576
EXPECT_NEAR(HREIRAdjustment, 0.936788, 0.00001); // =1 + (0.9 - 1) * 0.63212
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Fails without, works fix fix

// InletAirDryBulbC = 20, InletAirWetBulbC = 17
// TotalCondHeatingCapacity = TotalTUHeatingCapacity = 20000
// HeatingPLR = 0.25 (TUHeatingLoad = 3000, 3000/20000 = 0.15)
// HeatingPLR = 0.1875
//
// VRF(VRFCond).ElecHeatingPower = (VRF(VRFCond).RatedHeatingPower * TotHeatCapTempModFac)
// * TotHeatEIRTempModFac * EIRFPLRModFac *
// * HREIRAdjustment * VRFRTF * InputPowerMultiplier;
//
// TotHeatCapTempModFac and TotHeatEIRTempModFac are 1 because CAPFT/EIRFT curves aren't assigned,
// and anyways they wouldn't be used since VRF(VRFCond).HeatingPerformanceOATType isn't specifyied
// VRFRTF = 1.0 because not cycling below min PLR
// EIRFPLRModFac is 1 because EIRFPLR curve output is constant as 1.0 above
// InputPowerMultiplier is 1 because no defrost
EXPECT_EQ(VRF(VRFCond).ElecHeatingPower, VRF(VRFCond).RatedHeatingPower * VRF(VRFCond).VRFCondPLR * HREIRAdjustment);

}

} // end of namespace EnergyPlus