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Address Coil:Cooling:DX Doesn't Use the Minimum Outside Air Temperature for Compressor Operation Field #11131

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mitchute merged 12 commits intodevelopfrom
coil_cooling_dx_min_OAT
Sep 30, 2025
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Address Coil:Cooling:DX Doesn't Use the Minimum Outside Air Temperature for Compressor Operation Field #11131
mitchute merged 12 commits intodevelopfrom
coil_cooling_dx_min_OAT

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@Nigusse Nigusse commented Jul 24, 2025 •
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Pull request overview

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@Nigusse Nigusse added the Defect Includes code to repair a defect in EnergyPlus label Jul 25, 2025
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Nigusse commented Jul 25, 2025 •
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Ran a defect for two different values of the Minimum Outdoor Dry-Bulb Temperature for Compressor Operation {C} input field; ran for a default value of -25.0C and 25.0C. The plots below demonstrate the fix. The broken orange line shows the DX cooling coil is off when the outside air temperature is below the OA temperature limit of 25.0C.

image

@Nigusse Nigusse added this to the EnergyPlus 25.2 milestone Jul 25, 2025
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Nigusse commented Jul 25, 2025 •
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Uploaded test file.

UnitarySystem_VSCoolingCoilidf.txt

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Nigusse commented Jul 25, 2025
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Enabled the Coil:Cooling:DX coil object operation control using the outside air temperature minimum limit.

src/EnergyPlus/Coils/CoilCoolingDXCurveFitOperatingMode.cc

if ((speedNum == 0) || ((speedNum == 1) && (speedRatio == 0.0)) || (inletNode.MassFlowRate == 0.0)) {
if ((speedNum == 0) || ((speedNum == 1) && (speedRatio == 0.0)) || (inletNode.MassFlowRate == 0.0) ||
(state.dataEnvrn->OutDryBulbTemp < this->minOutdoorDrybulb)) {
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The Coil:Cooling:DX cooling coil object operation is disabled when the outside air temperature is below the minimum limit allowed for compressor operation.

src/EnergyPlus/Coils/CoilCoolingDXCurveFitOperatingMode.hh Outdated
Real64 ratedAirVolFlowEMSOverrideValue = 0.0;
bool ratedTotCapFlowEMSOverrideON = false;
Real64 ratedTotCapFlowEMSOverrideValue = 0.0;
Real64 minOutdoorDrybulb = 0.0;
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Defined member variable and set value to 0.0. Hmmm, maybe I should have set to the default value.

src/EnergyPlus/Coils/CoilCoolingDXCurveFitPerformance.cc
this->alternateMode2.minOutdoorDrybulb = this->normalMode.minOutdoorDrybulb;
this->myOneTimeMinOATFlag = false;
}
}
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The OA temperature minimum limit values propagated to operating mode variables. This is one time setup.

tst/EnergyPlus/unit/Coils/CoilCoolingDXCurveFitOperatingMode.unit.cc
EXPECT_EQ(performance->normalMode.minOutdoorDrybulb, 5.0);
EXPECT_EQ(performance->alternateMode.minOutdoorDrybulb, 5.0);
EXPECT_EQ(performance->alternateMode2.minOutdoorDrybulb, 5.0);
EXPECT_EQ(thisCoil.totalCoolingEnergyRate, 0.0);
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Modified an existing unit test to demonstrate the fix.

src/EnergyPlus/Coils/CoilCoolingDXCurveFitPerformance.hh
CoilCoolingDXCurveFitOperatingMode normalMode;
CoilCoolingDXCurveFitOperatingMode alternateMode; // enhanced dehumidifcation or Subcool mode
CoilCoolingDXCurveFitOperatingMode alternateMode2; // Reheat mode
bool myOneTimeMinOATFlag = true;
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A new flag variable is defined and set true for controlling a onetime run of the oneTimeMinOATSetup() function.

rraustad
rraustad reviewed Jul 25, 2025
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nrel-bot-2c commented Aug 30, 2025

@Nigusse @Myoldmopar it has been 30 days since this pull request was last updated.

@mitchute mitchute self-requested a review September 24, 2025 18:38
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mitchute commented Sep 29, 2025

One more round of CI to cleanup final issues, then merging (hopefully).

@mitchute mitchute merged commit 1820e01 into develop Sep 30, 2025
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@mitchute mitchute deleted the coil_cooling_dx_min_OAT branch September 30, 2025 00:33
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Defect Includes code to repair a defect in EnergyPlus

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Coil:Cooling:DX doesn't use MinOAT or AvailSched inputs

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