Multistage economizer control #9987

lymereJ · 2023-04-28T20:10:40Z

Pull request overview

Address 2 speed operation with Air Economizer in UnitarySystem #6109
This pull request adds a new feature to EnergyPlus that enables users to simulate an "economizer first" approach when modeling an economizer in a sensible-only load-controlled unitary systems with multispeed (or variable speed) fans and multispeed (or variable speed) coils. The new approach lets the economizer operation dictates the system flow rate instead of being decided based on the cooling coil speed (current approach). This new feature allows to simulate the performance of commercially available economizer controller for such systems more closely.

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nrel-bot-2b · 2023-05-27T00:08:59Z

@lymereJ @Myoldmopar it has been 28 days since this pull request was last updated.

nrel-bot · 2023-05-27T00:14:31Z

@lymereJ @Myoldmopar it has been 28 days since this pull request was last updated.

…ld overcool and 100% at the lower speed would not be enough. The approach used is to run at both speeds to meet the load and average the flow rate. Add a new function to get the a fan DT at a specific mass flow rate and airflow ratio.

src/EnergyPlus/DataHVACGlobals.hh

src/EnergyPlus/MixedAir.cc

amirroth · 2023-06-02T18:06:18Z

src/EnergyPlus/MixedAir.cc

+                            int unitarySystemNum = UtilityRoutines::FindItemInList(
+                                unitarySystemName, state.dataUnitarySystems->unitarySys, state.dataUnitarySystems->numUnitarySystems);
+                            if (state.dataUnitarySystems->unitarySys[unitarySystemNum - 1].m_ControlType ==
+                                UnitarySystems::UnitarySys::UnitarySysCtrlType::Load) {


Not part of this PR, but I would like to point out that in this fully-resolved name, UnitarySys appears THREE times! So, what you're telling me is that this is related to unitary systems?

amirroth · 2023-06-02T18:07:22Z

src/EnergyPlus/UnitarySystem.cc

-                //      IF (UnitarySystem(UnitarySysNum)%AirFlowControl .EQ. UseCompressorOnFlow) THEN
                if (this->m_FanOpMode == DataHVACGlobals::ContFanCycCoil) {
                    if (CoolSpeedNum == 0) {
                        state.dataUnitarySystems->CompOffMassFlow = this->MaxNoCoolHeatAirMassFlow;


Random questions, why are these essentially global variables?

lymereJ · 2023-08-18T01:50:41Z

Thanks for the review! I'll provide the plots later when I can get back to my desk.

…

On Thu, Aug 17, 2023, 6:20 PM Richard Raustad ***@***.***> wrote: @Myoldmopar <https://github.com/Myoldmopar> I have reviewed, and provided some comments. There is some trick stuff going on here and I'll give those things a 10. I especially like how economizer control was inserted in the air flow IF blocks (whether or not they are correct at this point). I am a little hesitant on actually setting air system air flow characteristics and I guess OA controller properties (mixed air node SP), but hey, think outside the box. Another 10 in my opinion, even if it doesn't work. I'll wait to see some final plots of the econo choices before I approve. I hope those plots come through clean in about an hours time without seeing something of note. I also looked at diffs and don't see any real differences. Point me to a file that concerns you, if I missed something that is. — Reply to this email directly, view it on GitHub <#9987 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABHJEX5TXFCE2GD4K67DLVLXV27PHANCNFSM6AAAAAAXPVCMUM> . You are receiving this because you were mentioned.Message ID: ***@***.***>

lymereJ · 2023-08-18T05:57:48Z

Well, I broke everything, but I think that I know what I did wrong, I'll reset to the last good commit, re-address the conflicts, and test locally first before pushing.

Ok, I reverted the previous merge and re-did it correctly, I think. I also updated the new example file following the latest changes to develop, and made changes based on Richard's comments. The example file ran fine locally, I'm hoping that the CI will come back "clean" (as in the same types/magnitude of diffs as before).

@rraustad, here are the plots you requested for three consecutive days. Outdoor air is in orange for the InterlockedWithMechanicalCooling and maroon for the EconomizerFirst. Blue is the supply fan air flow rate for the EconomizerFirst case. The bottom panel shows the cooling rate.

System 1

System 2

System 3

System 4

rraustad · 2023-08-18T14:48:21Z

@lymereJ what I was looking for was an increase in fan flow without compressor operation. It appears to me that all these plots show that econoFirst does that. @Myoldmopar from what I see this branch is doing exactly what is intended.

The only pause I have is this line in MixedAir. The mixer return node is set by the sum of the zone returns. I don't think that should be calculated/changed in the mixer code. It may be that this is the correct flow rate for this calculation of the mixer node flows, but I think the correct flow rate will wind up at the mixer return node naturally. It's the concept of stomping on what other components have already set.

state.dataLoopNodes->Node(thisOAController.RetNode).MassFlowRate = thisOAController.MixMassFlow - thisOAController.ExhMassFlow;

@lymereJ if this line is deleted, what happens?

Myoldmopar · 2023-08-18T14:51:42Z

Thanks @rraustad, that's great to hear! I will kick off a local build of this branch and if we don't hear back from @lymereJ I can even setup a second build with that line removed and run tests/regressions.

Other than that, CI results look much better, only very minor small diffs and warmup convergence style changes. So I agree this is probably very close.

rraustad · 2023-08-18T15:20:12Z

The mixer return node is the air loop supply side return, which is "connected" to the demand side outlet node. That node, the mixer return, is set/updated by the air loop manager and is a node that is tested for convergence. This is from the new example file UnitarySystem_MultiSpeedDX_EconoStaging.

OutdoorAir:Mixer,
  Sys 1 Furnace DX Cool OA Mixing Box,  !- Name
  Sys 1 Furnace DX Cool Mixed Air Outlet,  !- Mixed Air Node Name
  Sys 1 Furnace DX Cool Outdoor Air Inlet,  !- Outdoor Air Stream Node Name
  Sys 1 Furnace DX Cool Relief Air Outlet,  !- Relief Air Stream Node Name
  Sys 1 Furnace DX Cool Air Loop Inlet;  !- Return Air Stream Node Name   <-- this node

AirLoopHVAC,
  Sys 1 Furnace DX Cool,   !- Name
  ,                        !- Controller List Name
  Sys 1 Furnace DX Cool Availability Managers,  !- Availability Manager List Name
  autosize,                !- Design Supply Air Flow Rate {m3/s}
  Sys 1 Furnace DX Cool Branches,  !- Branch List Name
  ,                        !- Connector List Name
  Sys 1 Furnace DX Cool Air Loop Inlet,  !- Supply Side Inlet Node Name  <-- is this node
  Sys 1 Furnace DX Cool Return Air Outlet,  !- Demand Side Outlet Node Name
  Sys 1 Furnace DX Cool Supply Path Inlet,  !- Demand Side Inlet Node Names
  Sys 1 Furnace DX Cool Heating Coil Outlet;  !- Supply Side Outlet Node Names

That node gets updated/set in:

HVACInterfaceManager::UpdateHVACInterface(state,
                                          ZoneGroupNum,
                                          DataConvergParams::CalledFrom::AirSystemDemandSide,
                                          state.dataAirLoop->AirToZoneNodeInfo(ZoneGroupNum).ZoneEquipReturnNodeNum(RetAirPathNum),
                                          state.dataAirLoop->AirToZoneNodeInfo(ZoneGroupNum).AirLoopReturnNodeNum(RetAirPathNum),
                                          SimAir);

Myoldmopar · 2023-08-18T15:31:05Z

I just built this branch and ran it happily, all tests pass. I did a second build of this branch where I commented that line out, once again it built and ran all tests passing. I then ran a regression between the two branches and got zero diffs whatsoever. I think you are right that that line is not necessary, so we can just comment/remove that line and maybe this will be ready to merge. If that's correct, I'll push that up shortly, or @lymereJ feel free to chime in.

rraustad · 2023-08-18T15:46:36Z

I'm surprised there were no diffs, but then that's a very good thing. Delete that line and then this branch can merge.

Myoldmopar · 2023-08-18T16:09:31Z

Pushed 👍

Myoldmopar · 2023-08-18T16:09:46Z

I'll let the basic GHA runs get going then merge shortly.

Myoldmopar · 2023-08-18T16:17:48Z

I was hoping to catch it before Decent got started, but missed it. I'm going to merge this but I"ll leave the branch temporarily so that Decent can finish its runs. Thanks @lymereJ for this enhancement. Thanks @rraustad for so much review; it seems like this PR is triggering some interesting refactoring ideas to me.

lymereJ · 2023-08-18T16:24:38Z

Sorry for only getting back now. I wish I would have better documented the reason behind adding that line, right now, I got nothing. Perhaps it's a leftover from me testing things. I was going to suggest to comment it out to leave a trace in case an issue comes up but it looks like that's exactly what you did, thanks! For the record, I did run a full annual simulation for the new example file, the table files are the same, and I see some very negligible diffs in the ESO.

rraustad · 2023-08-18T18:26:56Z

src/EnergyPlus/UnitarySystem.cc

+        auto outdoorAirController = state.dataMixedAir->OAController(this->OAControllerIndex);
+        using Psychrometrics::PsyCpAirFnW;
+        Real64 cpAir = PsyCpAirFnW(state.dataLoopNodes->Node(outdoorAirController.InletNode).HumRat);
+        Real64 zoneTemp = state.dataLoopNodes->Node(state.dataZoneEquip->ZoneEquipConfig(this->ControlZoneNum).ZoneNode).Temp;


@lymereJ if the UnitarySystem is set up for Setpoint control, this->ControlZoneNum will be 0. Can you quickly test that to make sure there is no crash here, or check for Load control early on so this doesn't crash?

@rraustad - We do check for load control early on but we just use the outcome to display a warning the system is controlled by setpoint, so I think it will crash. I can add a check for type of control in the if statement below so we don't perform economizer staging calculations if the system is setpoint controlled.
From:

this->m_EconoSpeedNum = 0; if (this->OAControllerEconomizerStagingType == DataHVACGlobals::EconomizerStagingType::EconomizerFirst) { manageEconomizerStagingOperation(state, AirLoopNum, FirstHVACIteration, ZoneLoad); }

To:

this->m_EconoSpeedNum = 0; if (this->OAControllerEconomizerStagingType == DataHVACGlobals::EconomizerStagingType::EconomizerFirst && this->m_ControlType == UnitarySysCtrlType::Load) { manageEconomizerStagingOperation(state, AirLoopNum, FirstHVACIteration, ZoneLoad); }

Would that work for you?

I checked and I don't think we need to do anything here. manageEconomizerStagingOperation is only called from controlUnitarySystemOutput which is only used for load based systems. So if a model uses the new Controller:OutdoorAir input, it won't change anything to the simulation. Moreover, the PR added a warning message to let the user know that that if that input is selected in that context it won't do anything.

rraustad · 2023-08-18T18:35:18Z

src/EnergyPlus/UnitarySystem.cc

+            state, firstHVACIteration, mixedAirFlowRate, mixedAirFlowRate / this->m_CoolMassFlowRate[this->m_NumOfSpeedCooling]);
+        // determine new mixed air setpoint
+        Real64 newMixedAirSP = zoneTemp - std::abs(zoneLoad) / (cpAir * mixedAirFlowRate);
+        state.dataLoopNodes->Node(mixedAirNode).TempSetPoint = newMixedAirSP - fanDTAtMixedAirFlowRate;


@lymereJ this new control puts a SP on the mixed air node that tries to control the OA system to meet the zone load. That's fine, but 1) is stomping on the mixed air SPM, and 2) the user does not know anything about this override. In fact I'm not even sure this is doing anything because the SPMs and OA system are simulated before the UnitarySystem. Here's another case where I want to know what happens if this SP control is removed. If it's necessary then fine, but the user needs to know what is happening in their simulation. If this in fact is needed then I think this should be described in the docs and the "Unitary System Mixed Air Setpoint Temperature" be reported out to the user.

rraustad · 2023-08-18T18:38:06Z

src/EnergyPlus/UnitarySystem.cc

+
+                    // recalculate the outdoor air fraction to meet the new mixed air setpoint at the new mixed air flow rate
+                    MixedAir::ManageOutsideAirSystem(
+                        state, state.dataAirLoop->OutsideAirSys(this->OASysIndex).Name, firstHVACIteration, airLoopNum, this->OASysIndex);


Oh, I see, the OA system gets called from the UnitarySystem. I previously thought that only the air loop control properties were set in UnitarySystem. So that means the mixed air set point IS getting used, and that calculation of that SP is necessary. This is pointing to a new report for "Unitary System Mixed Air Setpoint Temperature".

I was just going through your comments one more time, so just to confirm, there's is nothing to add here, is that correct? The user should be able to get the setpoint set by the unitary system by requesting the system node setpoint temperature output variable.

I think viewing the SP on the node will be sufficient for now.

Myoldmopar · 2023-08-18T18:39:35Z

It does look like there is one fatal error, but only showing up on Windows oddly: https://myoldmopar.github.io/EnergyPlusBuildResults/EnergyPlus-273aede840425898126ac7f34ce658436f17297f-Win64-Windows-10-VisualStudio-16.html#test

Please try to reproduce that and fix it when you push any additional commits.

lymereJ · 2023-08-18T19:10:32Z

@Myoldmopar - Really odd, I ran the test on my Windows machine and it passes.

rraustad

Lot's of work here to include OA system operation with UnitarySystem performance. Nice effort.

rraustad · 2023-08-21T12:46:38Z

src/EnergyPlus/UnitarySystem.cc

+
+                    // recalculate the outdoor air fraction to meet the new mixed air setpoint at the new mixed air flow rate
+                    MixedAir::ManageOutsideAirSystem(
+                        state, state.dataAirLoop->OutsideAirSys(this->OASysIndex).Name, firstHVACIteration, airLoopNum, this->OASysIndex);


I think viewing the SP on the node will be sufficient for now.

lymereJ added 12 commits November 28, 2022 15:22

Add intial version of the NFP. [decent_ci_skip]

22cacad

Merge branch 'develop' into multistage_econ

2370f29

Add design document and small edits to the NFP.

391d2c7

Merge branch 'develop' into multistage_econ

4b726dd

Update NFP based on comments.

c296d86

Preliminary code changes.

efeace6

Clean up.

8ec0131

Update mixed air temperature setpoint calcs.

d8a845d

Adjust mixed air flow rate for autosized rated flow rate for VS coils.

0fe224e

Add example file and warning when new feature is not being applied.

5ab822e

Merge branch 'develop' into multistage_econ

19bc26f

Do not perform verification if air loop index is not valid.

2495086

lymereJ added NewFeature Includes code to add a new feature to EnergyPlus IDDChange Code changes impact the IDD file (cannot be merged after IO freeze) labels Apr 28, 2023

lymereJ added this to the EnergyPlus 23.2 IOFreeze milestone Apr 28, 2023

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amirroth reviewed Jun 2, 2023

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src/EnergyPlus/DataHVACGlobals.hh Show resolved Hide resolved

amirroth reviewed Jun 2, 2023

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amirroth reviewed Jun 2, 2023

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lymereJ added 7 commits June 5, 2023 14:16

Unit tests, address comments, reformatting.

b270b3a

Add unit tests.

6ec7a72

Merge develop.

c469833

Revert test file changes.

460ebe3

Revert test file changes.

21f13cc

Update example file and minor fixes.

cb05389

Remove unused vars.

8564008

lymereJ added 3 commits August 17, 2023 22:12

Correctly merge develop and address conflicts.

671fbbd

Update example file following the input changes from develop.

049d941

Address review comments.

dc6e415

lymereJ force-pushed the multistage_econ branch from 9a0e34c to 521a469 Compare August 18, 2023 05:42

Clang!

774adc1

Remove unnecessary flow rate override per @rraustad

aaceb01

Myoldmopar merged commit 273aede into develop Aug 18, 2023

lymereJ linked an issue Aug 18, 2023 that may be closed by this pull request

2 speed operation with Air Economizer in UnitarySystem #6109

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rraustad reviewed Aug 18, 2023

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lymereJ mentioned this pull request Aug 18, 2023

2 speed operation with Air Economizer in UnitarySystem #6109

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rraustad reviewed Aug 21, 2023

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mjwitte mentioned this pull request Aug 24, 2023

Fix variable speed heating coil defrost power #10109

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Myoldmopar deleted the multistage_econ branch October 17, 2023 15:14

rraustad mentioned this pull request Dec 11, 2024

Consolidate speed-dependent coil load ratio input parameters into a single parameter. #10369

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tanaya-mankad mentioned this pull request Jan 16, 2025

Small diffs during warmup in Economizer regression test #10898

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Multistage economizer control #9987

Multistage economizer control #9987

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