Fix GAHP flow request by lymereJ · Pull Request #11068 · NatLabRockies/EnergyPlus

lymereJ · 2025-05-19T22:58:23Z

Pull request overview

Fixes Gas-Fired absorption heat pump flow control issue #11067

Description of the purpose of this PR

Fix gas-fired absorption flow requests.

Pull Request Author

Title of PR should be user-synopsis style (clearly understandable in a standalone changelog context)
Label the PR with at least one of: Defect, Refactoring, NewFeature, Performance, and/or DoNoPublish
Pull requests that impact EnergyPlus code must also include unit tests to cover enhancement or defect repair
Author should provide a "walkthrough" of relevant code changes using a GitHub code review comment process
If any diffs are expected, author must demonstrate they are justified using plots and descriptions
If changes fix a defect, the fix should be demonstrated in plots and descriptions
If any defect files are updated to a more recent version, upload new versions here or on DevSupport

Reviewer

github-actions · 2025-05-20T19:49:33Z

⚠️ Regressions detected on macos-14 for commit `41c650f`

Regression Summary

ESO Big Diffs: 1

lymereJ · 2025-05-20T20:02:35Z

Here are the results for the (GAHP) defect file after updating it to 25.2 and with this branch.

Here's the updated file:
large_office_6A_vav_hw_reheat_out_gahp.idf.zip

lymereJ · 2025-05-20T20:22:16Z

ESO diff explanation:
Unlike the defect file, in develop, the example file shows flow rate through the unit, but because the load on the loop is small the GAHP does not use any gas (see code change walk-through). With this branch, the unit has a fuel rate and heat transfer greater than 0 during these times which I think is correct. See screenshot below (develop is on top, results from this branch are at the bottom).

lymereJ

Code changes walkthrough:

lymereJ · 2025-05-20T20:24:09Z

src/EnergyPlus/PlantLoopHeatPumpEIR.cc

                                                                        : this->sourceSideDesignMassFlowRate;

-            if (!FirstHVACIteration && this->flowControl == DataPlant::FlowMode::VariableSpeedPump) {
+            if (!FirstHVACIteration && this->flowMode == DataPlant::FlowMode::VariableSpeedPump) {


Use flowMode to be consistent with the enum class name.

lymereJ · 2025-05-20T20:26:06Z

src/EnergyPlus/PlantLoopHeatPumpEIR.cc

    }
 }

+void EIRFuelFiredHeatPump::setOperatingFlowRatesASHP(EnergyPlusData &state, bool FirstHVACIteration, Real64 const currentLoad)


Set the flow rates at the same time as EIRPlantLoopHeatPumps. Move the logic from EIRFuelFiredHeatPump::doPhysics here.

lymereJ · 2025-05-20T20:27:30Z

src/EnergyPlus/PlantLoopHeatPumpEIR.cc

-    if (partLoadRatio < this->minPLR) {
-        this->fuelRate = 0.0;
-        this->powerUsage = 0.0;
-    } else {
-        this->fuelRate = this->loadSideHeatTransfer / (this->referenceCOP * CRF) * eirModifierFuncPLR * eirModifierFuncTemp * eirDefrost;
+    this->fuelRate = this->loadSideHeatTransfer / (this->referenceCOP * CRF) * eirModifierFuncPLR * eirModifierFuncTemp * eirDefrost;


The previous behavior was to zero out the fuel rate when the partLoadRatio was less than the minPLR which triggered instances where the unit was not using any energy.

lymereJ · 2025-05-20T20:28:40Z

tst/EnergyPlus/unit/PlantLoopHeatPumpEIR.unit.cc

+        bool firstHVAC = true;
+        Real64 curLoad = 100;
+        bool runFlag = true;
+        Real64 constexpr specifiedLoadSetpoint = 45;
+        state->dataLoopNodes->Node(thisHeatingPLHP->loadSideNodes.outlet).TempSetPoint = specifiedLoadSetpoint;
+        state->dataLoopNodes->Node(thisHeatingPLHP->loadSideNodes.inlet).Temp = 40;
+        state->dataLoopNodes->Node(thisHeatingPLHP->sourceSideNodes.inlet).Temp = 30;
+        thisHeatingPLHP->simulate(*state, myLoadLocation, firstHVAC, curLoad, runFlag);
+        EXPECT_TRUE(thisHeatingPLHP->fuelRate > 0);
+        EXPECT_NEAR(5.0, thisHeatingPLHP->loadSideMassFlowRate, 0.001);
+    }


Test to check that fuelRate > 0 when partLoadRatio < minPLR.

lymereJ · 2025-05-20T20:29:08Z

tst/EnergyPlus/unit/PlantLoopHeatPumpEIR.unit.cc

+    {
+        bool firstHVAC = false;
+        Real64 curLoad = 2000;
+        bool runFlag = true;
+        Real64 constexpr expectedLoadMassFlowRate = 0.0478;
+        Real64 constexpr specifiedLoadSetpoint = 45;
+        state->dataLoopNodes->Node(thisHeatingPLHP->loadSideNodes.outlet).TempSetPoint = specifiedLoadSetpoint;
+        state->dataLoopNodes->Node(thisHeatingPLHP->loadSideNodes.inlet).Temp = 35;
+        state->dataLoopNodes->Node(thisHeatingPLHP->sourceSideNodes.inlet).Temp = 30;
+        thisHeatingPLHP->flowMode = DataPlant::FlowMode::LeavingSetpointModulated;
+        thisHeatingPLHP->simulate(*state, myLoadLocation, firstHVAC, curLoad, runFlag);
+        EXPECT_NEAR(expectedLoadMassFlowRate, thisHeatingPLHP->loadSideMassFlowRate, 0.001);
+    }


Test to check the variable flow logic.

# Conflicts: # src/EnergyPlus/PlantLoopHeatPumpEIR.cc

github-actions · 2025-05-23T22:17:37Z

⚠️ Regressions detected on macos-14 for commit `4e46c89`

Regression Summary

Table Big Diffs: 3
ESO Big Diffs: 1

rraustad · 2025-05-27T17:23:45Z

src/EnergyPlus/PlantLoopHeatPumpEIR.cc

-        }
+    this->powerUsage = this->nominalAuxElecPower * eirAuxElecFuncTemp * eirAuxElecFuncPLR;
+    if (this->defrostType == DefrostType::Timed) {
+        this->powerUsage += this->defrostResistiveHeaterCap * this->defrostOpTimeFrac * reportingInterval;


Why is reportingInterval included here? It was included before but looks odd. It seems that defrostOpTimeFrac * reportingInterval = seconds and J/s * s = joules. So powerUsage += joules ??

Yes, that does not seem correct. Should I make the change in this PR? Or, open an issue and fix it in a different one?

I think go ahead and make the change here rather than opening a new PR.

github-actions · 2025-05-27T19:16:30Z

⚠️ Regressions detected on macos-14 for commit `d32fe3a`

Regression Summary

Table Big Diffs: 3
ESO Big Diffs: 1

Myoldmopar · 2025-05-28T13:41:47Z

Alright, and with that fix in place, I think this is good to go in. Thanks for spotting it @rraustad and thanks for the quick fix up @lymereJ. This checks out locally and is ready to go, merging.

Fix GAHP flow request.

8302581

lymereJ added the Defect Includes code to repair a defect in EnergyPlus label May 19, 2025

lymereJ added this to the EnergyPlus 25.2 IO Freeze milestone May 19, 2025

lymereJ and others added 4 commits May 19, 2025 16:53

Update tests.

607d856

Merge branch 'develop' into fix_gahp_flow

d077a17

Fix test failures.

768f473

Add unit tests.

413cbfe

NatLabRockies deleted a comment from github-actions bot May 20, 2025

lymereJ commented May 20, 2025

View reviewed changes

lymereJ marked this pull request as ready for review May 20, 2025 20:29

lymereJ mentioned this pull request May 21, 2025

Fix order of curve independent variables for GAHP #11071

Merged

16 tasks

Merge branch 'develop' into fix_gahp_flow

05d1ef9

# Conflicts: # src/EnergyPlus/PlantLoopHeatPumpEIR.cc

rraustad reviewed May 27, 2025

View reviewed changes

Remove reportingInterval for defrost power penalty.

3945b70

Myoldmopar merged commit dfa3d53 into develop May 28, 2025
9 checks passed

Myoldmopar deleted the fix_gahp_flow branch May 28, 2025 13:41

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lymereJ commented May 19, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Pull request overview

Description of the purpose of this PR

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github-actions bot commented May 20, 2025

⚠️ Regressions detected on macos-14 for commit 41c650f

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lymereJ commented May 20, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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lymereJ commented May 20, 2025

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github-actions bot commented May 23, 2025

⚠️ Regressions detected on macos-14 for commit 4e46c89

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github-actions bot commented May 27, 2025

⚠️ Regressions detected on macos-14 for commit d32fe3a

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Myoldmopar commented May 28, 2025

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lymereJ commented May 19, 2025 •

edited

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⚠️ Regressions detected on macos-14 for commit `41c650f`

lymereJ commented May 20, 2025 •

edited

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⚠️ Regressions detected on macos-14 for commit `4e46c89`

⚠️ Regressions detected on macos-14 for commit `d32fe3a`