Eye-opening GSHP System Performance · Eye-opening GSHP System Performance: ... Closed-Circuit...
45
Stephen Hamstra, PE, CGD Greensleeves LLC [email protected] Eye-opening GSHP System Performance: Reality versus Design for the life of a Project Session C: Technical
Transcript of Eye-opening GSHP System Performance · Eye-opening GSHP System Performance: ... Closed-Circuit...
StephenHamstra,PE,CGDGreensleevesLLC
Eye-opening GSHP System Performance: Reality versus Design for the life of a Project
Session C: Technical
Learning Objectives• Our industry needs real performance feedback to grow:
How do we get it?
• Design Phase In-situ testing versus “Effective” GHX properties, do we see a difference?
• What about the building loads changing?
• When there is a difference from design to reality, what can be done to optimize system performance?
• How do we close the performance feedback loop?2
Acknowledgements• Shane Mason, P.E. – Greensleeves LLC
• Abe Glas, P.E. – Greensleeves LLC
• Zhicheng Zhang – Greensleeves LLC
• Ross Ulberg – Greensleeves LLC
• Bob Braam –Greensleeves LLC
3
Outline/Agenda
4
1. Design,construct,operateandoptimize;Whatcanhappentomakethingsdifferent?
2. CaseStudies
A. OverheatedFloridaHighSchool
B. Hot/coldborefieldsinNorthCarolinaVAFacilities
C. TheMichiganhighschoolthat“grewtoomuch”
D. TheMichiganhighschoolthatissavingtheOwnerbig$$$inconstruction
E. AnIowajailthat’sthe“hot”placetobe
F. Ilikecows,youshouldtoo
3. Conclusions&A Challenge
Design Process
5
Energymodeling In-situFormationTesting IterativeprocessofGHXsimulations
Design Process
6
Construction Process
7
The construction is finally done…
8
9
©HBOBoardwalkEmpire
10
11
Butfirst,anexplanation.
Solar Thermal Systems
Heat Exchangers to Sewer or Irrigation systems
Ground-Source Heat Exchanger(s)
Manyconfigurationoptions!
Energy Plant(s)
HEAT TRANSFER
Thermal Energy Storage
HEAT TRANSFER
CHP & Emergency Power Systems
Closed-CircuitCooling Towers
Bodies ofWater
Air-Source Heat Pump
HEA
T TR
ANSF
ER
Data & Control
Building Automation
System
Ground-Source Heat Exchanger
Site-based Energy Heat Pump Systems
12
HEAT TRANSFEREnergy Plant(s)Closed-CircuitCoolingTowerCCCT
Data & Control
Building Automation
System
Reactive v. Predictive Control
Reactive(Real-time)or“ASHRAEHybrid”Mode:
• WhenGHXleavingwatertemperaturesexceedasetpoint, theCCCTisenabled
• Typicallythisiswhen:o Outsideairtemperatureishottesto Outsideairhumidity ishighesto Electricityisthemostexpensive
• TypicallyusesMOREENERGYthanfullsize GHX
Predictive(Pre-Conditioning)Mode:
• Intelligentcontrols“look”toafuturehorizonandpredictGHXLWT’s
• IntelligentlydecidewhentooperatetheCCCT:o Cooleranddryerweathero Lessexpensiveenergyo Lesswaterusage
• Self-adaptingalgorithmsadjustautomaticallyCanuseLESSENERGYthanfullsize GHX!
13
GHX
Time shifting Heat Rejection?
14
RunHo
urs
WetBulbTemp°F
Or explained in another way…
15
• RunningaCCCTcreatesan“artificial”heatingload
o Especiallywhenruninthewintermonthsduring
coolweather– makesPhysicsworkforus!
• Inrealitywearesimplybalancing theannualcoolingand
heatingloads
o Weknowthatbalanced borefieldsworkbetter!
• Wearealsoresettinganypotentialtemperaturecreep
fromyeartoyear
UncontrolledFullsize GHX
ControlledFullsize GHX
HEAT TRANSFEREnergy Plant(s)Closed-CircuitCoolingTowerCCCT
Data & Control
Building Automation
System
Reactive v. Predictive Conclusion…
Reactive(Real-time)or“ASHRAEHybrid”Mode: Predictive(Pre-Conditioning)Mode:
16
GHX
Notreally…
©StarWars©BacktotheFuture
Overheated Florida High School
17
• Builtin2000
• Nominal1,000tonpeakcooling load
• Issueswithborefield installation– varyingdepthsand32coiledloops
• Installedapproximately179borefeetperpeaktonofcooling
• Temperaturesstartedtocreepreachingwellover100°+Frange
• Compressor failuresstartedin2006– notethesearenon-extendedrangeGSHP’s
• 2014– diagnosticsoftwarewasinstalledtotracktheloadsandtheGHXresponse
Overheated Florida High School
18
Actualloadsv.DesignLoads
Overheated Florida High School
19
Seven(7)yearsimulation results;addinganominal375toncooling tower:
Every dollar spent on the CCCT returns nearly $8!!!
(-76%) (-100%)
North Carolina VA Housing
20
• Two(2)housingunits– onemountain,onevalley
• Singlepipeheatpumpconfiguration
• Sixseparateborefields (GHX’s)perbuilding
• ProblemswithoverheatingGHXaswellas
overcooling (noantifreeze)
21
North Carolina VA Housing
22
North Carolina VA Housing
“Effective”GHXThermalConductivity
Red=ActualBlue=Predicted
North Carolina VA Housing #1
23Whenboth heatingandcoolingoccur,wecandoalong-termin-situtestonthe“effective”GHXThermalConductivity
1.63
0.74
1.5
1.68 1.72
1.11
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
GHX1 GHX2 GHX3 GHX4 GHX5 GHX6
DesignTC "Effective"TC
AVG 1.40(– 11%)
Design 1.57
North Carolina VA Housing #2
24Whenboth heatingandcoolingoccur,wecandoalong-termin-situtestonthe“effective”GHXThermalConductivity
1
0.78
1.14
0.51
1.14
1.36
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
GHX1 GHX2 GHX3 GHX4 GHX5 GHX6
DesignTC "Effective"TC
AVG 0.99(– 30%)
Design 1.41
North Carolina VA Housing
25
• SignificantvarianceinGHXeffectiveperformanceversusdesign
• SomevarianceofactualHVACloadstodesign– someduetotemperaturesetpoint changes
o Residentspreferwarmertemperaturesallyear– addedheatingload,diminished cooling load
• Singlepipedesignexacerbatedtheimpactof“outofrange”enteringwatertemperaturescausingfrequentGSHP
trips
• Butmostinterestingisthattheloaddiversitywasgreatenoughsuchthatifallsix(6)
GHX’s(eachbuilding)werecombined,theEWT’scouldstaywithintheneededrange
CurrentlytheyarecombiningtheGHX’s
Results:
26
Growing High School
• Builtin2001,Natatoriumaddedin2005
• Severalmajoradditions totheGHSPSystem,butnotGHX
• SummerGSHPEWTclimbsto120°F+!
• Numerousnuisancetripsandunhappy occupants
• Applied loadmonitoring softwaretosortitout…
27
Growing High School
• Majorirrigationsystemforathleticfields
• Runsnightlyinsummerfor6to8hours
• Citywatertemperaturesinthe60’s°Frange
• IrrigationpipepassesthroughGHXmechanicalroom
• Serendipity!
• Let’susetheirrigationasaclosed-circuitcoolingtower!
Observations:
28
Growing High School• IsolatedtheGHXflowfromthebuilding
• Added theirrigationHX
• Irrigationheatrejectioncanhit100+tons!
• Loadmonitoring softwarealsousedtoidentifyGHXcapacity– coulditsupport1MMBTUsnowmelt?Yes!
Growing High School
Growing High SchoolEnterin
gWaterTe
mp’s
Notewhenirrigation turnedoff!125°F!!!
80°F!!!
The “BIG” Borefield
31
• Builtin2003
• OriginaldesignofGHX:48°FMinto85°FMax
• Actualoperation: 55°Fto75°F,extracapacityavailable!
• Loadmonitoring softwareinstalled
• Newschoolbuilding proposed tobeconstructedadjacent
with$900,000GHX…
• Butbyknowing theavailablecapacityandhaving theproper
controls, theSchoolDistrictcantiethenewbuilding intothe
oldGHXandredirectconstructiondollars!
One “Hot” County Jail
32
• Builtin2009
• 58tonpeakload
• 9.9:1coolingdominant
• GHXleavingwatertemperaturescreptto115°F
One “Hot” County Jail
• Apply38tonCCCT
• Operatereal-timein“ASHRAEHybrid”mode
Option#1:Real-timeCCCTApproach
One “Hot” County Jail
34
• Apply38tonCCCT
• Operateinpre-conditioning mode
Option#2:PredictiveCCCTApproach– looktothefuture!
One “Hot” County Jail
35
Real-time Predictive
LowerEWT=LowerCoolingEnergy!
One “Hot” County Jail
36
Simulation results;addinganominal38toncoolingtower:
ExistingGHX Real-timeMode Pre-conditioningMode
MinGHXTemperature 70°F 68°F 63°F
MaxGHX Temperature 115+°F 96°F 90°F
LoadAdjusted GHXTemperature
Notsureyet! 81°F 73°F8°Fcooler!
CCCTkWH NA 13,751 11,34317.5%less
CCCTWaterkGal NA 159 8149%less
One “Hot” County Jail
37
Dropping from81°Fto73°FLoad-adjustedEWT:
Approx.11%less
Dairy Application????
38
• 2500dairycattle
• Eachcowproduces75poundsofmilkperday
• Mustbechilledfrom98°Fto38°F
o Thisisabout10,500BTU’spercow
• Milkinggoeson24/7– noofftime
• Alsoneedaround5.5gallonsofhotwaterpercow
perdayforcleaningandflushing
• ThisisCalifornia– majorwaterissues
Does “time shifting” heat rejection make sense???
Dairy Application????
39
SystemConcept:
• HeatRecoveryCentralHeatPump(nominal40tons)
• Makechilledfluidforchillingmilk
• Makehotwaterforcleaningpurposes
• SmallverticalclosedloopGHX (1.4borefeet percow)
• Smallclosed-circuitcoolingtower(15or36tons)
Did it “work”????
40
Versusconventionalwater-cooledrefrigeration,noheatrecoveryandnoGHX:
• Reductioninwaterusageperyear:
o 15tonCCCT: 79%less!!!
o 36tonCCCT: 87%less!!!
• Energycostreduction?
o Naturalgas(cheap)istough,maybe2-3%lessorroughlyequal.
o Propaneisnobrainer,like25%less!
Bottomline:TimeshiftingheatrejectioncanmakesenseinMANYapplications!
Bessieishappy!
Conclusions
41
1. Wecan’tfixwhatwecan’tmeasure,norcanweoptimizeit.
2. ConsiderincludingperformancetrackinganalyticsonEVERYPROJECT(neworold):
A. Measurerealbuildingloads(GHXflowrate)andcomparetodesignand/or
historicalloads
B. MeasurerealGHXresponse(GHXentering/leavingtemperaturesandoutsideair
temperature)
Conclusions
42
3. Forecastwhenthingsaregoingsouth,BEFOREtheissuehits!
4. Knowhowtoaddressachangeinloads…forreal,notjustguessing
5. Knowwhatistheavailablecapacityforfutureadditions
43
Let’s have projects that better and smarter over time!
A Challenge
Then we will too!
44
CominginNovember:FreeOnlineGSHPScopingTool!
• 16standardcommercialbuilding types(NREL)• 16ASHRAEClimateZones• ConventionalHVACv.GSHPFullsize GHX&Preconditioned GHX – FirstCostandEnergyCost
