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

Nigusse · 2021-03-10T18:37:12Z

Pull request overview

Fixes VS DX cooling coil outlet air condition calculation problem when PLR is zero for CV system #8543
This change skips calculating the VS dx cooling coil air outlet condition when the compressor PLR is zero and a continuous fan with VS cooling coil to avoid throwing psychometric error message in certain condition and thereby reduces the burden of computation.
Diffs are not expected

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Add to this list or remove from it as applicable. This is a simple templated set of guidelines.

Reviewer

This will not be exhaustively relevant to every PR.

Nigusse · 2021-03-10T18:44:52Z

src/EnergyPlus/VariableSpeedCoils.cc

+        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);


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.

Nigusse · 2021-03-10T18:45:20Z

tst/EnergyPlus/unit/UnitarySystem.unit.cc

@@ -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;


Added this to correct a failing unit test.

Nigusse · 2021-03-10T18:45:42Z

src/EnergyPlus/VariableSpeedCoils.cc

+            state.dataVariableSpeedCoils->LoadSideOutletHumRat = PsyWFnTdbH(state, state.dataVariableSpeedCoils->LoadSideOutletDBTemp, state.dataVariableSpeedCoils->LoadSideOutletEnth, RoutineName);
+            if (state.dataVariableSpeedCoils->LoadSideOutletHumRat > MaxHumRat) {
+                state.dataVariableSpeedCoils->LoadSideOutletHumRat = MaxHumRat;
+            }


This is part of the same change.

Nigusse · 2021-03-10T18:46:33Z

tst/EnergyPlus/unit/VariableSpeedCoils.unit.cc

+    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);
+}


New unit test.

Nigusse · 2021-03-10T18:47:28Z

tst/EnergyPlus/unit/VariableSpeedCoils.unit.cc

+    // 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);


This shows the coil outlet node air condition matches that of the inlet air condition when the PLR is zero.

Nigusse · 2021-03-11T16:21:04Z

This is branch is ready for review.

mjwitte · 2021-03-12T22:25:36Z

@Nigusse Is there a defect file for this? Any before/after results to look at?

Nigusse · 2021-03-15T13:49:52Z

@mjwitte defect file is attached. This is the same defect file we used for issue #8497.
RAT_VAVSys_wZnMxYes_AddInf_woDiningExhFan.idf.txt

I just run the defect file before and after the fix. The fix has eliminated the error message from CalcVarSpeedCoilCooling() function, where this fix was done but there is also the same error message coming from calls made in other unknowm function. But the recurring error message has reduced.

Before the fix:

   ** Warning ** Enthalpy out of range (PsyTsatFnHPb)
   **   ~~~   **  Routine=Unknown, Environment=JANUARY RUN, at Simulation time=01/01 05:40 - 06:00
   **   ~~~   **  Enthalpy=-45222.26861 Pressure= 99500.00
   **   ~~~   **  Initial Resultant Temperature= -59.98
   ** Warning ** Calculated Humidity Ratio invalid (PsyWFnTdbH)
   **   ~~~   **  Routine=CalcVarSpeedCoilCooling, Environment=JANUARY RUN, at Simulation time=01/02 00:40 - 01:00
   **   ~~~   **  Dry-Bulb= -55.00 Enthalpy= -55543.063
   **   ~~~   ** Calculated Humidity Ratio= -1.1253E-004 ... Humidity Ratio set to .00001
   ************* The following recurring error messages occurred.
   *************
   *************  ** Warning ** Enthalpy out of range (PsyTsatFnHPb)
   *************  **   ~~~   **   This error occurred 14 total times;
   *************  **   ~~~   **   during Warmup 0 times;
   *************  **   ~~~   **   during Sizing 0 times.
   *************  **   ~~~   **   Max=-42623.546441 J/kg  Min=-50704.132749 J/kg
   *************
   *************  ** Warning ** Calculated Humidity Ratio invalid (PsyWFnTdbH)
   *************  **   ~~~   **   This error occurred 43 total times;
   *************  **   ~~~   **   during Warmup 0 times;
   *************  **   ~~~   **   during Sizing 0 times.
   *************  **   ~~~   **   Max=-1.031273E-004 []  Min=-2.962171E-003 []

After the fix:

   ** Warning ** Calculated Humidity Ratio invalid (PsyWFnTdbH)
   **   ~~~   **  Routine=Unknown, Environment=JANUARY RUN, at Simulation time=01/07 05:40 - 06:00
   **   ~~~   **  Dry-Bulb= -59.98 Enthalpy= -66350.122
   **   ~~~   ** Calculated Humidity Ratio= -2.5404E-003 ... Humidity Ratio set to .00001
   ************* The following recurring error messages occurred.
   *************
   *************  ** Warning ** Enthalpy out of range (PsyTsatFnHPb)
   *************  **   ~~~   **   This error occurred 14 total times;
   *************  **   ~~~   **   during Warmup 0 times;
   *************  **   ~~~   **   during Sizing 0 times.
   *************  **   ~~~   **   Max=-42623.546441 J/kg  Min=-50704.132749 J/kg
   *************
   *************  ** Warning ** Calculated Humidity Ratio invalid (PsyWFnTdbH)
   *************  **   ~~~   **   This error occurred 8 total times;
   *************  **   ~~~   **   during Warmup 0 times;
   *************  **   ~~~   **   during Sizing 0 times.
   *************  **   ~~~   **   Max=-6.352259E-004 []  Min=-2.962171E-003 []

mjwitte · 2021-03-15T14:01:22Z

@Nigusse Thanks. Is there a significant impact on energy use or leaving node conditions?

Nigusse · 2021-03-15T14:05:48Z

@mjwitte Let me run annual simulation and get back to you.

Nigusse · 2021-03-15T14:37:21Z

@mjwitte Annual energy consumption are identical. Based on the code changes energy use and DX coil outlet condition difference is not expected.

Nigusse · 2021-03-15T14:38:15Z

@mjwitte I will merge in develop and push the branch.

Nigusse · 2021-03-15T15:35:04Z

See below the zone mean air temperature and supply air temperature before and after the fix. They are identical.

mjwitte · 2021-03-15T15:35:35Z

@Nigusse Oh, ok, that's good. But I'm confused, why is there no change in coil outlet condition? Was this calculation being overwritten later when the coil figures out it was off? I guess it would help if I open the full source file.

Nigusse · 2021-03-15T15:37:16Z

@mjwitte Yes, that is correct.

Nigusse · 2021-03-15T15:42:24Z

The benefit of this fix are avoid execcuting a code section that is not necessary when the PLR is zero and a continuous fan with VS cooling coil, thereby reduces the burden of computation and eliminates the PSych warning messages.

Nigusse · 2021-03-15T17:18:03Z

Building failed due to new unit test that needs updating to match some new dataLoopNodes globals. This is corrected now, built and ran the unit test suite locally, and all passed. I will push updated branch shortly.

mjwitte · 2021-03-15T19:57:22Z

@Nigusse This looks good except the "unknown" psych errors are bothersome. These are happening here in calTotcapSSHR_VSWSHP. Let's add the RoutineName argument to these Psych calls so the culprit for these warnings is identified. I'm not suggesting you figure out how to avoid these here. You can if you want, but I'm ok with just adding the function name here.

Nigusse · 2021-03-15T21:17:36Z

@mjwitte For now I will add the RoutineName only.

mjwitte · 2021-03-15T22:52:52Z

That works for me.

mjwitte

@Nigusse Looks like the Psych function arguments got added in #8577 instead of this branch, but that's not important. This one is good to go in.

Nigusse · 2021-03-16T03:38:21Z

@mjwitte I was suspicious because the line# where you commented was different but ended convincing myself that it was the correct one. I was switching between between branches working on the two issues.

nigusse added 4 commits March 10, 2021 12:57

VS DXCCoil in ContFanCycCoil_ZeroCompPLR Mode

fab99b3

Added unit test

65ca742

Address failed UnitarySystem unit test

917d4c6

Unit test cleanup

629a52a

Nigusse added the Defect Includes code to repair a defect in EnergyPlus label Mar 10, 2021

Nigusse changed the title ~~Address VS DX cooling coil outlet air condition calculation problem when PLR is zero or low~~ Address VS DX cooling coil outlet air condition calculation problem when PLR is zero Mar 10, 2021

Nigusse commented Mar 10, 2021

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Nigusse added this to the EnergyPlus 9.5.0 milestone Mar 11, 2021

Merge branch 'develop' into 176972354_Issue8543

ac6f2fd

Modified unit test to match dataLoopNodes globals

55c3808

Merge branch 'develop' into 176972354_Issue8543

9b5efd8

mjwitte mentioned this pull request Mar 15, 2021

Addresses zone air mass flow balance enforcing problem when there is "balanced" exhaust flow #8577

Merged

20 tasks

mjwitte approved these changes Mar 16, 2021

View reviewed changes

mjwitte merged commit cb7f35f into develop Mar 16, 2021

mjwitte deleted the 176972354_Issue8543 branch March 16, 2021 02:44

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

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

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

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

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