Chiller economizing using thermosiphon or fluid heat exchanger free cooling #10415

rraustad · 2024-02-27T19:11:40Z

Pull request overview

Fixes Chiller Refrigerant Migration free cooling #10179
Adds new features for:
New Feature for Chiller Thermosiphon (refrigerant migration without compressor operation)
Free Cooling in Air Cooled chillers
Integrated Water-Side Economizer with Air Cooled chiller (requires condenser loop)
Corrects an issue with the electric chillers where condenser inlet temperature uses the value from last time step. This should only affect heat recovery or chiller operating condition.

NOTE: ENHANCEMENTS MUST FOLLOW A SUBMISSION PROCESS INCLUDING A FEATURE PROPOSAL AND DESIGN DOCUMENT PRIOR TO SUBMITTING CODE

Pull Request Author

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

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EnergyArchmage · 2024-03-15T15:57:45Z

design/FY2024/NFP-Refrigerant-Migration-Decarbonization.md

+### Integrated water-side economizer with air-cooled chiller ###
+
+Integrated water-side economizer with air-cooled chillers is likely possible with existing objects with minor additions to control of the water flow through the WWHX (HeatExchanger:FluidToFluid). One side of the WWHX would be connected to the supply side inlet node of the chiller evaporator (or other appropriate branch in the plant, i.e., pre-cool entire plant loop) while the other side of the WWHX would be connected to a demand side branch of the condenser loop. Activation of the condenser loop flow through the HX, to activate free cooling, would be accomplished through controls modification (2). The WWHX object already has inputs for Control Type, Heat Exchanger Setpoint Node Name, Minimum Temperature Difference to Activate Heat Exchanger, Operation Minimum Temperature Limit, and Operation Maximum Temperature Limit. I am unsure at this time which of these fields would be used for configuration as an integrated water-side economizer or if other inputs would be required. It may be as simple as adding a new Control Type = IntegratedWaterSideEconomizer to allow the proper controls. Investigation into the new control will include review of the Component Override Loop inputs (e.g., using chiller condenser inlet or evaporator outlet node temperature as a control point).
+


I suspect you won't need to add a new control type to the WWHX. It can use a CoolingSetpoint* method. The chiller in series downstream is controlled by component setpoint based operation instead of load-based dispatch and should just pick up the modified temperatures.

CoolingSetpointOnOffWithComponentOverride is intended for the "all or nothing" parallel configuration. May need some testing.

EnergyArchmage · 2024-03-15T15:59:23Z

design/FY2024/NFP-Refrigerant-Migration-Decarbonization.md

+
+```
+HeatPump:PlantLoop:EIR:Cooling,
+  A13, \field Refrigerant Migration Temperature Difference Curve Name


I sort of like the word Thermosiphon over Refrigerant Migration

…-Refrigerant-Migration-Decarbonization

nrel-bot-2b · 2024-05-08T00:14:55Z

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

nrel-bot-2b · 2024-06-05T00:18:04Z

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

nrel-bot-3 · 2024-07-02T16:00:34Z

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

…-Refrigerant-Migration-Decarbonization

rraustad · 2024-07-26T04:27:11Z

src/EnergyPlus/ChillerReformulatedEIR.cc

@@ -2464,6 +2462,9 @@ void ReformulatedEIRChillerSpecs::calculate(EnergyPlusData &state, Real64 &MyLoa

    } // This is the end of the FlowLock Block

+    // set the module level variable used for reporting FRAC
+    this->ChillerCyclingRatio = FRAC;
+


Unit tests showed this was not getting set correctly. Moved this equivalence outside the above IF block to capture the proper value regardless of FlowLock.

rraustad · 2024-07-26T04:28:07Z

src/EnergyPlus/PlantChillers.cc

@@ -1528,6 +1528,7 @@ namespace PlantChillers {
        } // End of the Air Cooled/Evap Cooled Logic block

        Real64 condInletTemp = state.dataLoopNodes->Node(this->CondInletNodeNum).Temp;
+        this->CondInletTemp = condInletTemp; // needed if thermosiphon model is used


The new function uses this->CondInletTemp in the calculation so need to set this before that new function is called.

rraustad · 2024-07-26T04:29:15Z

src/EnergyPlus/PlantChillers.cc

+            if (this->thermosiphonDisabled(state)) {
+                this->Power = FracFullLoadPower * FullLoadPowerRat * AvailChillerCap / this->COP * FRAC;
+            }
+


Moved power calculation after where evap outlet temp is calculated.

rraustad · 2024-07-26T23:46:56Z

tst/EnergyPlus/unit/PlantLoopHeatPumpEIR.unit.cc

@@ -3465,13 +3479,42 @@ TEST_F(EnergyPlusFixture, TestOperatingFlowRates_FullyAutosized_AirSource)

    // call with run flag ON, flow locked at nonzero both
    state->dataPlnt->PlantLoop(1).LoopSide(DataPlant::LoopSideLocation::Supply).FlowLock = DataPlant::FlowLock::Locked;
-    state->dataLoopNodes->Node(thisCoolingPLHP->loadSideNodes.inlet).MassFlowRate = 0.14;
+    state->dataLoopNodes->Node(thisCoolingPLHP->loadSideNodes.inlet).MassFlowRate = 1.0;


Updated to avoid -24 C evap outlet temp.

rraustad · 2024-07-26T23:55:59Z

idd/Energy+.idd.in

@@ -73581,17 +73581,30 @@ Chiller:Electric:EIR,
       \note PLR is the chilled water plant loop part load ratio (actual/design)
       \type object-list
       \object-list UnivariateFunctions
-  A20, \field Temperature Difference Across Condenser Schedule Name
+  A19, \field Temperature Difference Across Condenser Schedule Name


Not sure why but the idd had a mismatch with alpha field numbers in several chiller models.

rraustad · 2024-07-27T00:04:47Z

src/EnergyPlus/ChillerElectricEIR.cc

+        return true;
+    }
+}
+


There is an issue here with this new function being in 4 different places. It would be better to locate this function somewhere so that there would only be 1 new function. And variable names would need to be unified. I should check to see if I made a mistake in Chiller:Electric.

Real64 capFrac = this->ChillerPartLoadRatio * this->ChillerCyclingRatio; // Electric:EIR Real64 capFrac = this->ChillerPartLoadRatio * this->ChillerCyclingRatio; // ReformulatedEIR Real64 capFrac = this->CyclingRatio; // PlantChillers, Chiller:Electric Real64 capFrac = this->partLoadRatio * this->cyclingRatio; // PlantLoopHeatPump:Cooling:EIR

UPDATE: Yes, it looks like Chiller:Electric needs to track both PLR and cycling ratio.
UPDATE: added partLoadRatio to Chiller:Electric and unified what these mean

Real64 capFrac = this->ChillerPartLoadRatio * this->ChillerCyclingRatio; // Electric:EIR Real64 capFrac = this->ChillerPartLoadRatio * this->ChillerCyclingRatio; // ReformulatedEIR Real64 capFrac = this->partLoadRatio * this->cyclingRatio; // PlantChillers, Chiller:Electric Real64 capFrac = this->partLoadRatio * this->cyclingRatio; // PlantLoopHeatPump:Cooling:EIR

UPDATE 7/27: added thermosiphon model to COP chiller.

Real64 capFrac = this->partLoadRatio * this->cyclingRatio; // Chiller:ConstantCOP

rraustad · 2024-07-27T00:47:29Z

Documenting previous diffs before partLoadRatio change to Chiller:Electric:

NFP-Refrigerant-Migration-Decarbonization (rraustad) - x86_64-Linux-Ubuntu-22.04-gcc-11.4: OK (3589 of 3697 tests passed, 175 test warnings)

283 tests had: AUD diffs.
279 tests had: RDD diffs.
131 tests had: Table small diffs.
108 tests had: Table big diffs.
1 test had: ESO small diffs.
1 test had: MTR small diffs.
1 test had: MTD diffs.
1 test had: EIO diffs.
1 test had: ERR diffs.

NFP-Refrigerant-Migration-Decarbonization (rraustad) - x86_64-MacOS-10.18-clang-15.0.0: OK (3548 of 3656 tests passed, 175 test warnings)

283 tests had: AUD diffs.
279 tests had: RDD diffs.
131 tests had: Table small diffs.
108 tests had: Table big diffs.
1 test had: ESO small diffs.
1 test had: MTR small diffs.
1 test had: MTD diffs.
1 test had: EIO diffs.
1 test had: ERR diffs.

rraustad · 2024-07-28T01:36:45Z

Results from new example file which has both the water-side economizer and the new thermosiphon model.

rraustad · 2024-07-28T13:02:24Z

All diffs, except for the 1 eio file ASHRAE901_Hospital_STD2019_Denver:

rraustad · 2024-07-28T14:07:00Z

src/EnergyPlus/ChillerElectricEIR.cc

@@ -1913,6 +1926,7 @@ void ElectricEIRChillerSpecs::calculate(EnergyPlusData &state, Real64 &MyLoad, b

    // If not air or evap cooled then set to the condenser node that is attached to a cooling tower
    Real64 condInletTemp = state.dataLoopNodes->Node(this->CondInletNodeNum).Temp;
+    this->CondInletTemp = condInletTemp; // needed for thermosiphon model


If I revert (comment out) this change in the EIR and ReformulatedEIR chillers there are no eio or results diffs in example file ASHRAE901_Hospital_STD2019_Denver. This was verified through Binder plot results and diffing the eio files. The Binder script skips a plot if there are no diffs otherwise the script creates a plot.

This branch:

After revert of this line in 2 places:

Example diff from this branch for ASHRAE901_Hospital_STD2019_Denver:

rraustad · 2024-07-28T16:33:42Z

src/EnergyPlus/PlantLoopHeatPumpEIR.cc

+                                              format("Invalid Thermosiphon Capacity Fraction Curve Name = {}",
+                                                     thermosiphonTempCurveName.value().get<std::string>()));
+                            errorsFound = true;
+                        }


Test severe error using PlantLoopHeatPump_EIR_LargeOffice-2-AWHP-AuxBoiler-Pri-Sec-4PipeBeam:

** Severe ** HeatPump:PlantLoop:EIR:Cooling ="AWHP_1 COOLING SIDE" ** ~~~ ** Invalid Thermosiphon Capacity Fraction Curve Name = ThermosiphonCurve2 ** Severe ** HeatPump:PlantLoop:EIR:Cooling ="AWHP_2 COOLING SIDE" ** ~~~ ** Invalid Thermosiphon Capacity Fraction Curve Name = ThermosiphonCurve3 ** Fatal ** Previous EIR PLHP errors cause program termination

rraustad · 2024-07-28T16:39:18Z

src/EnergyPlus/PlantChillers.cc

+                    ShowContinueError(state,
+                                      format("Invalid {} = {}", state.dataIPShortCut->cAlphaFieldNames(9), state.dataIPShortCut->cAlphaArgs(9)));
+                    ErrorsFound = true;
+                }


Test severe error using FreeCoolingChiller_wWaterSideEconomizer:

** Severe ** GetConstCOPChillerInput: Chiller:ConstantCOP="MAIN CHILLER" ** ~~~ ** Invalid Thermosiphon Capacity Fraction Curve Name = THERMOCAPFRACCURVE2 ** Fatal ** Errors found in processing input for Chiller:ConstantCOP

Myoldmopar

This is pretty impressive. High value addition for what appears to be like 2-3 hundred lines of code added. I'm going to play with this PR locally for a bit, but other than the repeated function, this is looking good from first inspection.

Myoldmopar · 2024-08-08T14:58:40Z

src/EnergyPlus/ChillerReformulatedEIR.cc

+    } else {
+        return true;
+    }
+}


Yeah, this really shouldn't be repeated, right? Just add a reusable utility function somewhere accessible, add a few intent(inout) arguments, and call it anywhere it's needed. UtilityFunctions probably isn't the right spot, but neither is GeneralRoutines. Or maybe one of them is the right spot? I dunno, and also this doesn't have to hold up this PR, but it is a bit odd to have copies of the same routine to maintain.

I wonder if such a routine would work in the plant component base class?

I did consider moving this to a common location but wasn't sure I knew what I was doing. The calculation inside this function would require unification of variables names in the chillers.

Real64 capFrac = this->ChillerPartLoadRatio * this->ChillerCyclingRatio; // Electric:EIR Real64 capFrac = this->ChillerPartLoadRatio * this->ChillerCyclingRatio; // ReformulatedEIR Real64 capFrac = this->partLoadRatio * this->cyclingRatio; // PlantChillers, Chiller:Electric Real64 capFrac = this->partLoadRatio * this->cyclingRatio; // PlantLoopHeatPump:Cooling:EIR Real64 capFrac = this->partLoadRatio * this->cyclingRatio; // Chiller:ConstantCOP

Myoldmopar · 2024-08-12T19:13:17Z

This still works fine with develop pulled in, let's just merge this in. Thanks @rraustad and @EnergyArchmage !

New Feater Proposal for plant decarbonization task

d55c402

rraustad added the NewFeature Includes code to add a new feature to EnergyPlus label Feb 27, 2024

rraustad added this to the EnergyPlus 24.2 IOFreeze milestone Feb 27, 2024

rraustad self-assigned this Feb 27, 2024

rraustad added 4 commits February 27, 2024 16:38

Update NFP [decent_ci_skip] [actions skip]

1ceb336

Add references [decent_ci_skip] [actions skip]

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NFP edits [decent_ci_skip] [actions skip]

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Correct NFP figure reference [decent_ci_skip] [actions skip]

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EnergyArchmage reviewed Mar 15, 2024

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rraustad added 3 commits April 8, 2024 08:19

Merge branch 'develop' of https://github.com/NREL/EnergyPlus into NFP…

53991f8

…-Refrigerant-Migration-Decarbonization

Update NFP and implement/test thermosiphon model

f882b68

Merge branch 'develop' of https://github.com/NREL/EnergyPlus into NFP…

6adc569

…-Refrigerant-Migration-Decarbonization

rraustad added 8 commits July 9, 2024 09:31

Already initialized

7223593

Merge branch 'develop' of https://github.com/NREL/EnergyPlus into NFP…

bc33ffe

…-Refrigerant-Migration-Decarbonization

clean up

704781a

Merge branch 'develop' of https://github.com/NREL/EnergyPlus into NFP…

1f6dfc7

…-Refrigerant-Migration-Decarbonization

Add thermosiphon to Chiller:Electric

891cb9e

Revert 1 minor change that was removed

2e76983

Merge branch 'develop' of https://github.com/NREL/EnergyPlus into NFP…

4bef040

…-Refrigerant-Migration-Decarbonization

Add thermosiphon to EIR chillers

5b6b8f3

rraustad added the IDDChange Code changes impact the IDD file (cannot be merged after IO freeze) label Jul 15, 2024

Minor update to doc and example file

5108f29

rraustad added the OutputChange Code changes output in such a way that it cannot be merged after IO freeze label Jul 17, 2024

rraustad added 3 commits July 24, 2024 17:59

Add new example file and update HX IORef doc

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Merge branch 'develop' of https://github.com/NREL/EnergyPlus into NFP…

274582b

…-Refrigerant-Migration-Decarbonization

Update idd and IORef

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rraustad added 2 commits July 25, 2024 19:37

Add chiller unit tests

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Merge branch 'develop' of https://github.com/NREL/EnergyPlus into NFP…

837b7a5

…-Refrigerant-Migration-Decarbonization

rraustad commented Jul 26, 2024

View reviewed changes

Final unit test

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rraustad commented Jul 26, 2024

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rraustad commented Jul 27, 2024

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Add partLoadRatio to Chiller:Electric, revise cyclingRatio meaning.

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rraustad added 4 commits July 27, 2024 20:18

Add new thermosiphon model to Chiller:ConstantCOP

3d6a472

Add Chiller:ConstantCOP unit test

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Update generic output section to include COP chiller

e2ecaee

Update example file

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rraustad commented Jul 28, 2024

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Add severe error for invalid thermosiphon capacity fraction curve name

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Fix PlantLoop:HeatPump:EIR:Cooling alphanumeric numbering

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mjwitte assigned Myoldmopar and mjwitte Jul 31, 2024

rraustad changed the title ~~New Feature Proposal for plant decarbonization~~ Chiller free cooling using thermosiphon or fluid heat exchanger Jul 31, 2024

rraustad changed the title ~~Chiller free cooling using thermosiphon or fluid heat exchanger~~ Chiller economizing using thermosiphon or fluid heat exchanger free cooling Jul 31, 2024

Myoldmopar reviewed Aug 8, 2024

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Myoldmopar merged commit c89c5c9 into develop Aug 12, 2024
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Chiller economizing using thermosiphon or fluid heat exchanger free cooling #10415

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Myoldmopar commented Aug 12, 2024

		### Integrated water-side economizer with air-cooled chiller ###

		Integrated water-side economizer with air-cooled chillers is likely possible with existing objects with minor additions to control of the water flow through the WWHX (HeatExchanger:FluidToFluid). One side of the WWHX would be connected to the supply side inlet node of the chiller evaporator (or other appropriate branch in the plant, i.e., pre-cool entire plant loop) while the other side of the WWHX would be connected to a demand side branch of the condenser loop. Activation of the condenser loop flow through the HX, to activate free cooling, would be accomplished through controls modification (2). The WWHX object already has inputs for Control Type, Heat Exchanger Setpoint Node Name, Minimum Temperature Difference to Activate Heat Exchanger, Operation Minimum Temperature Limit, and Operation Maximum Temperature Limit. I am unsure at this time which of these fields would be used for configuration as an integrated water-side economizer or if other inputs would be required. It may be as simple as adding a new Control Type = IntegratedWaterSideEconomizer to allow the proper controls. Investigation into the new control will include review of the Component Override Loop inputs (e.g., using chiller condenser inlet or evaporator outlet node temperature as a control point).

Chiller economizing using thermosiphon or fluid heat exchanger free cooling #10415

Chiller economizing using thermosiphon or fluid heat exchanger free cooling #10415

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