Better humidity control for chilled water coils and for AirloopHVAC:UnitarySystem #7215

mjwitte · 2019-03-08T19:05:23Z

Pull request overview

1. Addresses Array bounds error in GetCoilDesFlowT if time of cooling peak is not set #7211 to avoid array bounds violation in ReportSizingManager::GetCoilDesFlowT.
2. Adresses Improved chilled water coil humidity control #7001 by modifying Controller:WaterCoil to switch gears from controlling on temperature setpoint to controlling on humidity ratio when needed. This replaces the existing concept of adjusting the temperature setpoint with an approach temperature to achieve the humidity control.

Addresses UnitarySystem set point based control of humidity not working correctly #6892 to fix humidity control in AirloopHVAC:UnitarySystem. This is also alternate solution to Improved chilled water coil humidity control #7001, using AirloopHVAC:UnitarySystem to control the chilled water coil instead of Controller:WaterCoil. This required a few tweaks to avoid uninitialized variables and get things to control well, but this pegs the leaving dry-bulb setpoint or the leaving humidity ratio setpoint, and reliably switches between the two. (See EnergyPlusDevSupport\DefectFiles for an idf like this). At present, there are still some warnings of "Iteration limit exceeded calculating latent part-load ratio for unit", so may need some more tweaks, but that may just be how it is.

Chilled water coil
DX single speed

Defect Files

7001 defect file no longer crashes in debug build and maintains the Node 27 humidity ratio within 9.8e-05 of the humidity ratio setpoint of 0.011388. The jagged profile comes from using a humidity ratio control tolerance of 1.0e-04 (arbitrarily chosen to be tight, but not so tight that there are max iteration problems). Maybe that should be tighter.

For 6892 there are three defect files, 6892-in_Copy-HumCtrl, DOAS_CWCoil-UseUnitarySystem, DOAS_DXCoil-UseUnitarySystem:
DOAS_CWCoil-UseUnitarySystem - crashes with develop debug build, runs fine and controls almost exactly to setpoint with develop release build. This branch, runs fine and controls well with both release and debug builds.

DOAS_DXCoil-UseUnitarySystem - crashes with develop debug build, runs fine and does not control humidity with develop release build. T
his branch, runs fine and controls well with both release and debug builds.

Other Diffs Summary

HospitalBaseline, HospitalBaselineReheatReportEMS, HospitalLowEnergy, RefBldgHospitalNew2004_Chicago - small diffs in results, eio diffs are all in the warmup convergence details, and err diffs are either fewer or rearranged max iteration messages.

5ZoneCoolingPanel*, 5Zone*Baseboard*, 5ZoneWaterCooled*, HeatPumpWaterHeater* - eio diffs are all in the warmup convergence details, no err diffs, big diffs in results.

Reviewed 5ZoneCoolingPanelBaseboard results - Space2-1 humidity control is similar to before, still not pegged at 50%, main cooling coil load is 0.4% less, and main heating coil load is 0.8% less. Expect similar for the other cooling panel files.

Reviewed 5ZoneWaterCooled_Baseboard results - again humidity control is similar, coil loads 0.1%-0.4% less.

Reviewed HeatPumpWaterHeater results - similar humidity control, 0.04% higher main cooling coil load, 0.5% lower main heating coil load

Work Checklist

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

Title of PR should be user-synopsis style (clearly understandable in a standalone changelog context)
At least one of the following appropriate labels must be added to this PR to be consumed into the changelog:
- Defect: This pull request repairs a github defect issue. The github issue should be referenced in the PR description
- Refactoring: This pull request includes code changes that don't change the functionality of the program, just perform refactoring
- NewFeature: This pull request includes code to add a new feature to EnergyPlus
- Performance: This pull request includes code changes that are directed at improving the runtime performance of EnergyPlus
- DoNoPublish: This pull request includes changes that shouldn't be included in the changelog

Review Checklist

This will not be exhaustively relevant to every PR.

…ation

…Ctrl-7001

rraustad · 2019-03-11T15:15:03Z

src/EnergyPlus/ReportSizingManager.cc

        }
        if (CoolCapCtrl == VAV) {
            DesExitTemp = FinalSysSizing(SysNum).CoolSupTemp;
            DesFlow = FinalSysSizing(SysNum).MassFlowAtCoolPeak / StdRhoAir;
        } else if (CoolCapCtrl == OnOff) {
            DesExitTemp = FinalSysSizing(SysNum).CoolSupTemp;
            DesFlow = DataAirFlowUsedForSizing;
+        } else if (TimeStepAtPeak == 0) {


TimeStepAtPeak can't be 0 if VAV or OnOff fan control is used? If so then this line won't get hit. This IF test should be first in list?

Oh, I see. You put this IF test before those that use TimeStepAtPeak.

rraustad · 2019-03-11T15:24:25Z

src/EnergyPlus/ReportSizingManager.cc

        }
        if (CoolCapCtrl == VAV) {
            DesExitTemp = FinalSysSizing(SysNum).CoolSupTemp;
            DesFlow = FinalSysSizing(SysNum).MassFlowAtCoolPeak / StdRhoAir;
        } else if (CoolCapCtrl == OnOff) {
            DesExitTemp = FinalSysSizing(SysNum).CoolSupTemp;
            DesFlow = DataAirFlowUsedForSizing;
+        } else if (TimeStepAtPeak == 0) {
+            ShowFatalError("GetCoilDesFlow: AirLoopHVAC=" + SysSizInput(SysNum).AirPriLoopName +
+                           " Central Cooling Capacity Control Method requires zone thermostats to calculate timestep loads.");


You can still have a no design load condition (and therefore a 0 for time step at peak) even though a Tstat is used. Remember when zone return temp at heating peak was 0 and TU coils weren't sizing correctly? It's the combination of Tstat temp (i.e., zone temp during sizing) and supply air temp that yields a non-zero zone mass flow rate. Isn't there another way to know if a Tstat is used?

You're right, even with a tstat, there could be zero peak. So, should these methods throw a warning if there's no peak day/time and revert to one of the other methods?

Maybe change the warning text to say exactly what has happened (inside the else if's below) and revert to sizing with CoolSupTemp and MassFlowAtCoolPeak?

rraustad · 2019-03-11T15:25:25Z

src/EnergyPlus/HVACControllers.cc

@@ -1465,6 +1434,10 @@ namespace HVACControllers {
                (0.001 / (2100.0 * max(ControllerProps(ControlNum).MaxVolFlowActuated, SmallWaterVolFlow))) * (HVACEnergyToler / 10.0);
            // do not let the controller tolerance exceed 1/10 of the loop temperature tolerance.
            ControllerProps(ControlNum).Offset = min(0.1 * HVACTemperatureToler, ControllerProps(ControlNum).Offset);
+            if (ControllerProps(ControlNum).ControlVar == HVACControllers::iTemperatureAndHumidityRatio) {
+                // for temperature and humidity control, need tighter tolerance if humidity control kicks in
+                ControllerProps(ControlNum).Offset = ControllerProps(ControlNum).Offset*0.1;


Would be nice to be able to trigger a tighter tolerance only when HumRatCtrlOverride = true.

I tried that first but it didn't work. There's some initial setup step that I couldn't find that includes the offset.

rraustad · 2019-03-11T15:38:22Z

src/EnergyPlus/SimAirServingZones.cc

@@ -2960,6 +2963,31 @@ namespace SimAirServingZones {
                    // not converge
                    ControllerConvergedFlag = PrimaryAirSystem(AirLoopNum).ControlConverged(AirLoopControlNum);
                    IsUpToDateFlag = true;
+                } else {


This will require multiple more iterations of the air loop components. Wouldn't it be better to use the lesser of T and TdpFw as the temperature set point up at line 1283 - 1289 of HVACControllers?

I can try that on a separate branch, but I think it will over-dehumidify.

Or use T and TdpFw as a trigger to choose which set point to use, temperature or humidity ratio.

No, don't need to try that. The humidity ratio setpoint is 0.011388 which is roughly Tdp=15.9C. There are many hours where the coil can meet the humidity ratio setpoint with a leaving temperature of 16-17C, and there are many hours where the leaving air is saturated. That's why this needs to switch gears and can't just use Tdp.

Hmm, how can Tdp come out lower than supply air T? If a dry coil then yes, but a wet coil? Not your problem at this point.

'cause the water temp is well below Tdp, and some of the air bypasses the coil, so the resulting mix can be drier than saturation.

…ion 7211

…cape to top

…Ctrl-7001

mjwitte · 2019-03-12T12:25:58Z

So, the diffs are not good. The TemperatureAndHumidityRatio files with autosized controller tolerance now have a smaller tolerance by 10x which leads to max iteration problems, and the ones with a fixed controller tolerance of, e.g. 0.002 are too loose on the humidity control. Need to figure out how to have a variable tolerance - where that lives in the controller rootfinder stuff.

rraustad · 2019-03-12T13:12:53Z

Here's some data from the HVAC lab that does show supply air Tdp is lower than T dry-bulb. The TXV modulates the refrigerant outlet temperature and superheat varies from around 5F to 13F.

…Ctrl-7001

…tions

mjwitte · 2019-03-18T21:11:18Z

@Myoldmopar @rraustad This is ready for review. See diffs discussion at top of PR.

rraustad · 2019-03-20T20:24:29Z

7001 looks good.

rraustad · 2019-03-20T20:37:51Z

src/EnergyPlus/HVACControllers.cc

+                            // Turn on humdity control and restart controller
+                            IsConvergedFlag = false;
+                            thisController.HumRatCtrlOverride = true;
+                            if (thisController.Action == iReverseAction) {


This seems redundant but I'm OK with it. Controller should spit out warnings that it can't control temperature much less humidity.

rraustad · 2019-03-20T20:47:01Z

src/EnergyPlus/UnitarySystem.cc

@@ -10574,7 +10574,9 @@ namespace UnitarySystems {
                               (this->m_TESOpMode == PackagedThermalStorageCoil::OffMode ||
                                this->m_TESOpMode == PackagedThermalStorageCoil::ChargeOnlyMode)) {
                        PartLoadFrac = 0.0;
-                    } else {
+                    } else if (!SensibleLoad) {


Highlights an issue with all coils types when no sensible load exists and a latent load does. Logic at top of function could skip sensible PLR calcs and go directly to latent calcs. Sensible calcs are inside of if(SensibleLoad || LatentLoad) block.

rraustad · 2019-03-20T20:51:21Z

tst/EnergyPlus/unit/DXCoils.unit.cc

@@ -252,6 +252,9 @@ TEST_F(EnergyPlusFixture, DXCoils_Test1)
    DXCoilPartLoadRatio.allocate(1);
    DXCoilFanOpMode.allocate(1);

+    DataLoopNode::Node.allocate(1);
+    DXCoil(CoilIndex).AirOutNode = 1;
+


Wow, previously no Node calls inside the Calc routine, I wouldn't have guessed that but I guess Init sets up node data variables and uses them in Calc. Wonder what the node data variable shows in the Calc routine. Oh well, unit test passes what it's intended to do.

Other than the condenser inlet node, CalcDoe2DXCoil doesn't read or write to any nodes. It uses variables like DXCoil(DXCoilNum).InletAirTemp.

rraustad · 2019-03-20T21:02:14Z

tst/EnergyPlus/unit/ReportSizingManager.unit.cc

+    ReportSizingManager::GetCoilDesFlowT(sysNum, CpAir, designFlowValue, designExitTemp);
+    EXPECT_FALSE(has_err_output(true));
+    EXPECT_DOUBLE_EQ(DataSizing::FinalSysSizing(1).CoolSupTemp, designExitTemp);
+    EXPECT_DOUBLE_EQ(0.002, designFlowValue);


Must be some 0's in the data used to calculate designFlowValue = 0.002, but it passes.

Umm, this shouldn't be in here

Oh wait - never mind - all good here. Forgot what was in here.

rraustad

All looks good. Reviewed code and unit tests.

rraustad · 2019-03-20T21:05:14Z

src/EnergyPlus/PlantUtilities.cc

+            // early in simulation before plant loops are setup and found
+            a_node.MassFlowRate = CompFlow;
+            return;
+        }


This must have fixed something?

And neither should this be here.

Oh- right - this fixed an array bounds problem. d136c4c
@rraustad Thanks for the review and merge.

rraustad · 2019-03-26T13:22:15Z

@mjwitte @jmarrec @Myoldmopar my fault for not closing the issues, however, if the description had one of these keywords then those issues closed just now would have automatically closed when the PR was merged. I was getting used to that happening and forgot to check to make sure the issues were closed when the PR was merged. "Addresses" is not one of those keywords.

mjwitte · 2019-03-26T13:41:50Z

Yeah, well, sometimes I don't like the automatic closing, but I suppose I should conform.

rraustad · 2019-03-26T13:48:17Z

I have no problem with closing issues as we have in the past. I just thought from recent past experience that we were doing it this way now and mistakenly thought those issues would automatically close. Do it either way, I just have to be vigilant to always check.

mjwitte added 2 commits March 8, 2019 08:52

Temporary fix in GetCoilDesFlowT to protect against array bounds viol…

cb6f108

…ation

UnitarySystem fix humidity setpoint controls

3adf350

mjwitte added this to the EnergyPlus 9.1.0 milestone Mar 8, 2019

mjwitte added the Defect Includes code to repair a defect in EnergyPlus label Mar 8, 2019

mjwitte added 3 commits March 9, 2019 15:11

Merge remote-tracking branch 'remotes/origin/develop' into ChwCoilHum…

865c9f0

…Ctrl-7001

ChW controller improve temperature and humidity control

53543cb

ChW controller - delete now unused variables

7683df8

rraustad reviewed Mar 11, 2019

View reviewed changes

mjwitte added 8 commits March 11, 2019 15:41

Revised fix in GetCoilDesFlowT to protect against array bounds violat…

6c08857

…ion 7211

ChW controller - cleanup and move humctrl check into HVACControllers

119c5bc

ChW controller - remove unused FirstHVACIteration args

9451557

SetActuatedBranchFlowRate - avoid array bounds errors - move early es…

d136c4c

…cape to top

GetCoilDesFlowT_NoPeak - new unit test and cleanup

56330bd

HVACControllers_CheckTempAndHumRatCtrl unit test

ee06f4e

Merge remote-tracking branch 'remotes/origin/develop' into ChwCoilHum…

0bd833d

…Ctrl-7001

UnitarySystemModel_WaterCoilSPControl_Latent unit test

3f5a7e2

mjwitte added 2 commits March 12, 2019 08:37

ChW controller - vary offset only if needed for humidity control

4471a4e

Merge remote-tracking branch 'remotes/origin/develop' into ChwCoilHum…

c029acf

…Ctrl-7001

mjwitte mentioned this pull request Mar 18, 2019

UnitarySystem set point based control of humidity not working correctly #6892

Closed

3 tasks

mjwitte changed the title ~~Better humidity control for chilled water coils~~ Better humidity control for chilled water coils and for AirloopHVAC:UnitarySystem Mar 18, 2019

mjwitte added 3 commits March 18, 2019 11:58

UnitarySystem humidity controls - set node conditions in DX calc func…

7fda469

…tions

UnitarySystem humidity controls - fix unit test

7883673

UnitarySystem humidity controls - fix another unit test

040fa15

mjwitte requested review from Myoldmopar and rraustad March 18, 2019 21:09

rraustad reviewed Mar 20, 2019

View reviewed changes

rraustad approved these changes Mar 20, 2019

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rraustad reviewed Mar 20, 2019

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rraustad merged commit 31a9b31 into develop Mar 20, 2019

rraustad deleted the ChwCoilHumCtrl-7001 branch March 20, 2019 21:08

This was referenced Mar 26, 2019

Array bounds error in GetCoilDesFlowT if time of cooling peak is not set #7211

Closed

Improved chilled water coil humidity control #7001

Closed

mjwitte mentioned this pull request Dec 17, 2019

Convergence problem with Controller:WaterCoil and TemperatureAndHumidity control - need more plant iterations? #7653

Closed

3 tasks

mjwitte mentioned this pull request Jun 1, 2020

Fix Controller:WaterCoil chilled water temperature and humidity control #7980

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Better humidity control for chilled water coils and for AirloopHVAC:UnitarySystem #7215

Better humidity control for chilled water coils and for AirloopHVAC:UnitarySystem #7215

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mjwitte commented Mar 8, 2019 • edited Loading

Pull request overview

Defect Files

Other Diffs Summary

Work Checklist

Review Checklist

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mjwitte commented Mar 12, 2019

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rraustad commented Mar 26, 2019

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