robinson, j et al. - sustainable control systems in the modern home - enme 538
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SUSTAINABLECONTROLSYSTEMS INTHEMODERNHOME
GROUP10
FINALDESIGNREPORTPROJECTTEAM: NicolasAlexandreHamel-10075091
BraedenDanielHale-10104852RichardMurrayHudson-10104283MatthewLamoureux-10086715JordanRobinson-00290587DanCojocariu-10076421
ACADEMICADVISOR: Dr.KeDu DepartmentofMechanicalEngineering UniversityofCalgaryPROJECTSPONSOR: JohnBrown housebrandFACULTYADVISOR: Dr.SimonLi UniversityofCalgary
ENME538April8,2016
UniversityofCalgary
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EXECUTIVESUMMARY
Sustainabledesignsarebecomingincreasinglyimportanttohomeownersthatnotonlywanttosavemoney,butalsowanttohaveapositiveimpactontheenvironmentanditsresources.Thisprojectwasundertakentoallowtheaveragehomeownertoreducebothenergyusageaswellastreatedwaterusage.Twoautonomoussystemswerevigorouslyconceptualized,createdandtestedtovalidateproofofconcept.Thefirstisanautomatedin-linefansystemthattakesadvantageofthenaturallyoccurringtemperaturesinksintheaveragehome.Thissystemwouldbeusedtoredistributewarmandcoolairwithinthehome,andwouldsupplementtheexistingHVACsystemsalreadypresent.Thesecondisarainwatercollectionanddistributionsystem.Thissystemtakestheguessworkoutofwateringplants.Throughtheuseofmoisturecontentsensorsandapump,optimalsoilconditionsaremaintainedforeachplanttoreduceoverwatering.Throughtestingitwasdeterminedthatbothconceptswerecredible.Thein-linefansystemcooledtheupperstoryofahome50%fasterthannaturalconvection.Aswell,therainwaterdistributionsystemeffectivelyreadsoilsaturationlevelsanddeliveredwaterwhenneeded.ItwasalsodeterminedthatbothsystemshavethepotentialtosavemoneydirectlyandtohaveasignificantimpactonemissionswhendeployedinAlbertahomes.Bothsystemshaveshownpromiseafterpassingthroughtheearlystagesofprototypetestingandarereadyforthenextstepoffull-scaleimplementation.
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ACKNOWLEDGEMENTS
Group10wouldliketothanktheprojectsponsor,JohnBrownforhisassistancewiththe4thyeardesignproject.Moreover,theprojectsponsorhasprovidedmanylearning’sfortheteam.WewouldliketotakethisopportunitytothanktheprojectAdvisor,Dr.KeDufortheguidanceandmentorshiphehasprovidedasthegrouphasprogressedthroughtheproject.Lastly,wewouldliketothanktheDepartmentofMechanicalEngineeringincludingtheprofessoroftheCapstoneDesignCourse,andtheTeachingAssistantsfortheknowledgetheyhavesharedwithus.
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TABLEOFCONTENTS
ExecutiveSummary.....................................................................................................................................2
Acknowledgements.....................................................................................................................................3
TableofContents.........................................................................................................................................4
ListofTables................................................................................................................................................6
TableofFigures............................................................................................................................................6
ProjectOverview.........................................................................................................................................7
Background..............................................................................................................................................7
ProblemStatement..................................................................................................................................8
OverallGoalsandScope..........................................................................................................................8
ProblemDefinition.....................................................................................................................................10
CustomerRequirements........................................................................................................................10
ObjectivesandConstraints....................................................................................................................10
In-lineFanSystem..............................................................................................................................10
RainwaterManagement....................................................................................................................12
DesignFunctionsandSpecifications......................................................................................................14
ConceptGenerationAndSelection............................................................................................................19
DevelopmentandDescriptionsofDesignAlternatives.........................................................................20
In-LineFanSystem.............................................................................................................................21
RainwaterManagement....................................................................................................................21
AssessmentofDesignAlternatives........................................................................................................22
FinalDetailedDesign.................................................................................................................................25
OverviewoftheDesignConcept...........................................................................................................25
In-lineFan..........................................................................................................................................25
RainWaterManagement...................................................................................................................25
OverviewofKeyDesignComponents....................................................................................................25
In-lineFan..........................................................................................................................................25
RainWaterManagement...................................................................................................................26
ProjectCosts..........................................................................................................................................26
In-LineFan..........................................................................................................................................26
RainwaterManagement....................................................................................................................28
FeasibilityandRiskAssessment.............................................................................................................29
In-LineFan..........................................................................................................................................29
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RainwaterManagement....................................................................................................................31
VerificationandPrototypeTesting............................................................................................................34
In-LineFan..........................................................................................................................................34
RainwaterManagement....................................................................................................................45
Recommendations.....................................................................................................................................59
In-lineFan..........................................................................................................................................59
RainwaterManagement....................................................................................................................60
Conclusion.................................................................................................................................................62
References.................................................................................................................................................63
Appendices................................................................................................................................................65
AppendixA–RainwaterManagementExpenseReport........................................................................65
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LISTOFTABLES
Table1In-LineFanObjectiveRanking.......................................................................................................11Table2RainwaterManagementObjectiveRanking..................................................................................13Table3RainwaterManagementMorphologicalChart..............................................................................19Table4RainwaterManagementNumericalEvaluationMatrix.................................................................22Table5In-LineFanNumericalEvaluationMatrix......................................................................................23Table6RainwaterManagementMarkingCriteria....................................................................................23Table7In-LineFanMarkingCriteria..........................................................................................................24
TABLEOFFIGURES
Figure1In-LineFanInputs/Outputs..........................................................................................................15Figure2RainwaterManagementInputs/Outputs.....................................................................................16Figure3In-LineFanFunctionalBlockDiagram..........................................................................................17Figure4RainwaterManagementFunctionalBlockDiagram.....................................................................17Figure5RainwaterManagementFunction-MeansTree...........................................................................20Figure6In-LineFanFunction-MeansTree................................................................................................21Figure7CharacterizationofTMP-36temperaturesensorperformance..................................................35Figure8EffectofAirflowandVibrationofTMP-36Reliability..................................................................35Figure9.Conceptual(left)andPhysical(Right;ArduinoUno)LayoutsofINlineFanControlSysteM......36Figure10.ConceptualDiagramoftheCompletecontrolsystemoftheinlinefansystem.......................37Figure11.BasicthermalmodelofastandardhomewithanintegratedinlineFansystem......................37Figure12UserinterfaceandSystemDisplay.............................................................................................39Figure13ResultsofOperatingIn-LineFanSystem...................................................................................40Figure14SolidWorksModelSimulations..................................................................................................40Figure15FullScaleHome-SolidWorksModel.........................................................................................41Figure16Cut-awayofductat1/20ofscale..............................................................................................42Figure18PictureoftheEC-5Sensor(DecagonDevices,2015).................................................................46Figure19SensorCalibrationEquationsCompared...................................................................................47Figure20SensorThreshold-WateringSoil...............................................................................................48Figure21NoiseFoundinSensor2.............................................................................................................49Figure22DiscrepancyAmongSensorMeans............................................................................................50Figure23LocationofSolderedConnections.............................................................................................51Figure24SensorCalibrationTest-2SensorsinOneCup.........................................................................52Figure25SensorCalibrationTest–2SensorsinOneCupwithWaterAdded..........................................53Figure26PrototypeatDesignFair............................................................................................................54
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PROJECTOVERVIEW
Asconsumershavebecomemoreawareoftheenvironmentalfootprintofthesystemsintheirhomes,theyhaveincreasinglydemandedmoreproductsandservicesthataremoreenvironmentallyfriendly.However,asthenumberandcomplexityofthesesystemsgrows,thedirectandmanualcontrolofthesesystemsisbecomingprohibitive.Theemergenceofinexpensive,lowpower,andpowerfulmicrocontrollerspresentstheopportunitytocontrolsuchsystemsbasedonminimaluserinput.
Inthepresentprojectandreport,weintendtostudytheuseofmicrocontroller-operatedmechanicaldeviceswhichtakeadvantageofnaturally-occurringheatandresourcesinordertosavematerialcostsforhomeownerswhileatthesametimeimprovingthesustainabilityofmodernhomesthroughreductionsingreenhousegasemissionsandtreatedwaterusage.
BACKGROUND
ThecombinedproblemsofacceleratingglobalclimatechangeandlocaleconomicrecessioninAlbertaduetodepressedcommoditypricesareoftenperceivedtohavesolutionsthataremutuallyexclusive.Ontheonehand,technocraticsolutionstotheproblemofgrowinggreenhousegas(GHG)emissionsareoftenperceivedtobecomplex,niche,andprohibitivelyexpensiveforconsumers,whileconsumer-levelsolutionstoaneconomicrecessioninvolvecuttingmonthlyexpensesandtakingfewerrisksonless-proventechnologiesinthehome.Engineeringsolutionswhichcansolvebothproblemssimultaneously,however,presentopportunitiestomakegainswhichwillbewell-receivedbyhomeownersfortheircost-savingsandaboonforglobalclimatechangemitigationduetothecumulativeeffectofwidespreaddeployment,evenwithmodestindividualenvironmentalimpacts.
Sustainablehousingisacrucialelementinthepursuitofglobalclimatechangemitigation.TheGenevaUNCharteronSustainableHousingnotesthat‘sustainablehousinghasakeyroleinthequalityofhumanlife’(UNECE,2015).Aswellasimprovingsocialinclusionandculturaladequacy,sustainablehousingiscentraltoenvironmentalprotectionandtheeconomiceffectivenessofhousingingeneral.TheCharteradvocatesforafocusontheminimizationofenvironmentalimpactsandsustainabilitythroughtheretrofittingofexistinghomes‘asmuchaspossible,fortheefficientuseofresources’aswellas‘improved…energyperformanceofdwellings’(UNECE,2015).
InCanada,andAlbertaparticularly,therearetwocategoriesofenvironmentalimpactswhichofferthegreatestopportunitiesforimprovement:1)HVAC-dependentenergyefficiency,and2)outdoorwaterusage(Reference).In2011,Residentialhousingaccountedfornearly17%ofsecondaryenergyusageinCanada,andtheprimarydriverofenergyconsumptioninresidentialhomesareheating,ventilation,andairconditioning(HVAC)systems(NRCAN,2015).InAlberta,natural-gas-basedfurnacesaccountforjustover90%ofheatingsystemsinstalledinhomes,andairconditioningsystemsareelectricity-intensiveforthetypicallylarge-areahomesfoundinAlberta,andrelyonelectricityderivedfromaheavilypollutingcoal-basedelectricitygrid(NRCAN,2012).Additionally,in2011,Canadacontinuedtobeoneofthelargestper-capitaconsumersoffreshwaterintheworld,andhouseholdsaccountedfor43%ofthetotalfreshwaterusage(StatsCan,2012).Meanwhile,inAlberta,residentialdemandforwaterusagecontinuestogrow,despitetheeconomicrecession,andwatertreatmentplantsarereachingcapacity.ThereisthereforeapressingneedforimprovementsintheenvironmentalimpactsofresidentialhomesinCanada.
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Whilemanyhomeownersmaybemotivatedtoreducetheenvironmentalfootprintoftheirhomes,widescaledeploymentwillbegreaterwithmoreaffordablesolutions.Indeed,Canadianhomeownersactivelyinvestinretrofitsandrenovationstoimprovetheirlivingstandards(StatsCan,2012).AccordingtoStatisticsCanada,between2003and2007,50%ofhomeownerscompletedretrofitsspecificallytoimprovetheenergyefficiencyoftheirhomes,andmorethanaquarterofthoseretrofitsweredirectlyappliedtoexistingHVACsystems(StatsCan,2012;NRCAN,2015).Aswell,homeownersdemonstratedparticularinterestintheinstallationofwaterusagemetersandgreywatermanagementsystemswhereapplicable.
PROBLEMSTATEMENT
Weaimtodesignandanalysetwoautomatedsystemscentraltotheenvironmentalimpactofnormallyoperatinghomes.
1. Anautomatedairredistributionsystemforcoolingandheating 2. Anautomatedrainwatermanagementsystemforcollection,storageanddistributionofrainfall
Bothsystemshavethebenefitofreducingthestressplacedontheenvironmentbyahomeinahighlyfeasibleway.Weintendtoinvestigatetheadvantagesandopportunitiesofferedbytheaforementionedsystems,thenreportonourempiricalanddesignresults.
OVERALLGOALSANDSCOPE
Theprimaryobjectivesofthecurrentprojectaretogeneratefeasibleandaccessiblemechanicalengineeringsolutionsinordertoimprovethesustainabilityofmodernhomes.Specifically,weaimtodevelopsolutionhavingthepotentialgreatestimpacton1)thedirectreductionofwaterandenergycostsforhomeowners,2)thereductionofdirectandindirectenergyusagebyhomeowners,and3)thereductionofcumulativegreenhousegasemissionsandtreatedwaterusagedemandinAlberta,Canada,andglobally.
Inthepursuitofthosegoals,weintendtodeveloptwoelectromechanicalsystemsthathavethepotentialtodecreasetwoofthegreatestenvironmentalimpactsofmodernhomes:energyuseforindoorclimatecontrolandwateruseforoutdoorenvironmentcontrol.Tomitigatetheenergyusage,andsubsequentenvironmentalimpactsoftheformer,weintendtocreateapassiveenergysystemthatwillworkinconcertwithexistingstandardHVACsystems.Tomitigatewaterusage,andlimitthedemandfortreatedwaterusedforlawnmaintenanceandgardening,weintendtocreateanintelligentwatercollectionanddistributionsystemwhichcollectsthemaximumamountofrainwateranddistributeswatertoplantsbasedontheirindividualhorticulturalneeds.
Wewilltestthemechanicalperformanceofthetwosystemsandtheirrespectivesubsystems,bymeasuringandoptimizingresponsetime,controlsystemssensitivity,mechanicalsystemcapabilitiesintermsofheattransferandfluiddynamics,componentperformancelimits,reductionsinenergyandwaterdemand,reductionsinprojectedenvironmentalimpactsandlastbutnotleast,theabilitytorespondtoandprovideforhumancomfortdesiresandplanthorticulturalneeds.
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Ourtwosystemsareintendedtobeadaptabletoanymarketandlocationwhichstandstobenefitfromimprovementsinthemitigationoftheenvironmentalimpactsofstandardhomes,particularlywithrespecttoenergyusage,treatedwaterusage,GHGemissionreductions,andurbangardeningandfarmingactivities.Furthermore,weaimtofundamentallycontrolthecostandaccessibilityofthesesystemsbyimplementingthemechanicallysimplest,andthereforeleastexpensivepossiblesystemsupondeploymentaswellasbydesigningthesystemswithmodularity,suchthattheycanbeeasilytailoredtoavarietyofhomeowners'needs.Bykeepingcostslowanddesigningthesystemstoadapttoavarietyofneeds,weaimtoobtainthegreatestpossibleadoptionratesamongconsumersforsustainablehomesystems.Thiswillnotonlybebeneficialforthegrowthanddistributionofthesesystems,butwillalsohelptogenerateagreaterreductioninthecumulativeenvironmentalimpactsofhomes.
Thebenchmarktargetmarketsforoursystemsisthree-storeysingle-detachedhomesinAlberta,whichhavethegreatestpotentialdemandforhomerenovations.Thatis,wesurmisethathomesbuiltbetween10and30yearsagowillhavethegreatestdemandforsuchsystemssincenewerhomeswilllikelynothavehighdemandfornewbuildingcosts,andhomesolderthan30yearsmaybenefitmorefrommorefundamentalrenovationimprovementssuchasfurnacereplacements,insulation,waterlinefixesandwatermetering.
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PROBLEMDEFINITION
CUSTOMERREQUIREMENTS
Clientsfortheoverallprojectinclude:
1. Housebrandsponsorandcontact(JohnBrown) 2. Homebuyersinterestedinthesesystems 3. Homebuilderstowhomtheproductcouldbemarketed 4. Projectadvisor(Dr.KeDu) 5. MembersoftheCapstoneengineeringdesignteam
Regardlessofwhothecustomersareitisofgreatimportancethatbothproductsarecompletelyautonomous.Customersarelookingforinnovativecontrolsystemstoautomateeverydaysystemslocatedaroundthehome.Thesecustomersarealsointerestedinsavingresourcessuchaswater,electricity,andnaturalgas.Thesecontrolsystemsmustalsobeuserfriendly,withasimpleyeteffectiveuserinterface.
Itisveryimportantthatlabtestedtrialsandexperimentaldataisrecordedtoreinforcethefeasibilityofbothdesignsandtracktheprogressofdevelopment.Themajordeliverableexpectedbytheendoftheprojectisaprototypeofbothsystemstodemonstratetheirfunctionalityalongwithproofofanalysis.Asignificantpartofthisprojectisthecontrolsystemsthatdictatetheinformationtransferandoperationoftherequiredsensorsandactuatorsbythemicroprocessor.Thiswillbedisplayedinbothprototypes,andwillhighlighttheautomateddesignofboththein-linefanandwater-managementprojects.
Itwillalsobeagoodideatoshowcasetheimplementationandinstallationstrategyofbothdesigns.Showcasingthebenefitsandeaseofinstallationwillallowthecustomertoenvisionthefinalproductintheirownhomeandwillstrengthentheoverallconceptoftheproject.
OBJECTIVESANDCONSTRAINTS
IN-LINEFANSYSTEM
CONSIDERATIONANDRANKINGOFPROJECTOBJECTIVESANDCONSTRAINTS
Whentheprojectwasstillinitsearlystages,alistofobjectivesandconstraintsimportanttothedesignandanalysisofthein-linefansystemwasgenerated.Theseobjectivesweresummarizedunderthreemaincategories:
1. Installability-thesystemmustbeeasytointegrateintoexistinghousingsystems 2. Efficiency-thesystemmustreducecostandenergyrequirementstoaddvalue 3. Functionality-thesystemmustoperatebetterthanexistingHVACalternatives
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Thesublevelsofeachcategorywererankedaccordingtotheiroverallrelativeimportancetothefinaldesignasdeterminedatthepreliminarystageofthedesign.
TABLE1IN-LINEFANOBJECTIVERANKING
Category Objective Metric Rank
a.)Installability
i.Modular Lightandeasytolift,xxkg #7
ii.Attachedtostandardductwork Standardizedparts,yes/no #6
iii.Easilyincorporatedintohome Fitsintoducting,squaremeters #4
b.)Efficiency
i.Energy/Environment Energyconsumptionandheatexchange #3
ii.Powerconsumption Powerconsumedeachday,kWh(<1kWh/day) #11
iii.Audibility Minimalnoise,lowestdBpossible #10
iv.Durability Last5yearswithreliabilityof99% #8
v.Partsreadilyavailable UsesO-t-Sparts,yes/no #9
c.)Functional
i.Reachestemperaturein1h Responsetime,degreeC/min #2
ii.Reliablecontrolsystem Mustlast5-10yearswith99%reliability #5
iii.Thermostaticallycontrolled Respondaccuratelytoenvironment,yes/no #1
FIVESPECIFICATIONSCRITICALTOTHEDESIGN
Afterthelistofobjectivesabovewascreated,fiveobjectiveswereselectedasbeingthemostcritical.Itwasdeterminedthatthefollowingspecificationsmustbemetinordertodeemtheprojectasuccess
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uponcompletion.Foreachspecification,ametric(eitherasaminimumbenchmarkorperformancecharacteristic)wasdeclaredandeachwasclassifiedeitherasbeinganissueofperformance,procedure,orvalue.Listedinorderofimportance:
c.iii.)ThermostaticallyControlled(Yes,withacomplimentaryuserinterface)
-Procedure
c.i.)Reachestemperaturewithin1hr.(Temperatureshouldchangeatleast2deg/hr.)
-Performance
b.i.)Energy/Environment(Shouldconsume25%lesspowerthantraditionalHVAC)
-Values
a.iii.)Easilyincorporatedintohome(Systemiscompact;smaller=better)
-Procedure
c.ii.)ReliableControlSystem(Mustlast5-10yearswith99%reliability)
-Procedure
CONSIDERATIONOFHUMANINTERFACECONSTRAINTS
Theinterfaceofthein-linefansystemwasalsoconsidered.Abrieflistofcriticalissuesconcerningtheintegrationofthissystemintoanexistinghomeandthedesignoftheuserinterfacewascompiled.Anidealinterfaceforusersshouldhavethefollowingcharacteristics:
1. Beoperatedasanintelligentthermostat-(Userdefined)a. Timer,DesiredTemperature,TemperatureSchedule
2. Operateindependentlyextraneousvariables(Open/closebutterflyvalvestoredirectairflow)a. Customerinteractionwiththesystemshouldbelimited
3. Bemicro-controlleroperated;acceptsadesiredtemperatureinputfromoperator
RAINWATERMANAGEMENT
CONSIDERATIONANDRANKINGOFPROJECTOBJECTIVESANDCONSTRAINTS
Wehavecreatedalistoftheobjectivesandconstraintsthatareimportanttothedesignandanalysisoftherainwatermanagementsystem.Wehavesummarizedtheseobjectivesunderfourmaincategories:
1. Installability(thesystemmustbeeasytointegrateintoexistinghouses) 2. Efficiency(thesystemmustreducecostandenergyrequirementstobeofvalue) 3. Functionality(thesystemmustoperatebetterthanexistingalternatives) 4. Lifecycle(thesystemmustbedurabletoextendlifetimeandreducemaintenance)
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Thesublevelsofeachcategoryhavebeenrankedaccordingtotheiroverallrelativeimportancetothefinaldesignasdeterminedatthecurrentstageoftheproject.
TABLE2RAINWATERMANAGEMENTOBJECTIVERANKING
Category Objective Metric Rank
a.)Efficiency
i.Easingofenergy/environmentimpact kWhelectrical/litresofwater #8
ii.Reduceoverallwaterconsumption Litresofwatersavedperyear #1
iii.Collectandstorewaterdiscretely Aestheticappeal #7
iv.Footprint
• Audible&Physical
Shouldbequiet(dB)andcompact(square-meters) #9
b.)Lifecycle i.Durability Mustlastxyearswithxx%
reliability #6
ii.Accessibleparts Arereplacementpartsavailable #11
c.)Functionality
i.Abilitytostoreexcessivewater Sizeoftank(litres) #4
ii.Overflowprotection Responsetimetooverflow(sec) #5
iii.Reliablecontrolsystem Mustlastxyearswithxx%reliability #2
iv.Controllerbasedonsoilsaturation Mustmaintainsaturationlevelofxx #3
d.)Installability
i.Systemshouldbeadaptabletodifferenthousinglayoutsandplotsizes
Adaptabilityofthemaincomponentsofthesystem #10
ii.Designshoulddefinetheoptimalamountsandtypesofvegetation
Whatamountofcertainegetativespeciescanbeused #12
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FIVESPECIFICATIONSWHICHARECRITICALTOTHEDESIGN
Aswasdoneforthein-linefansystem,fiveobjectiveswereselectedasbeingmostcritical.Itisimperativethatthesespecificationsareachievedinordertoconsiderthisprojectasasuccessuponcompletion.Themetric,intheformofeitheraminimumbenchmarkorperformancecharacteristicisdeclared;eachisclassifiedeitherasbeinganissueofperformance,procedureorvalue.Listedinorderofimportance:
a.ii)Reduceoverallwaterconsumption(litresofwaterperyeartobedeterminedbasedonlotsize)
-Performance
c.iii)Reliablecontrolsystem(Mustlast5-10yearswith99%reliability)
-Procedure
c.iv)Controllerbasedonsoilconditions(Maintainwatersaturationbasedonvegetation)
-Procedure
c.i)Abilitytostoreexcessivewater(tanksizeinlitresbasedonlotsize)
-Values
c.ii)Overflowprotection(responsetimetooverflowinseconds)
-Values
CONSIDERATIONOFHUMANINTERFACECONSTRAINTS
Theinterfaceofthewatermanagementsystemwasalsoconsidered.Abrieflistofcriticalissuesconcerningtheintegrationofthissystemintoanexistinghomeandthedesignoftheuserinterfacewascompiled.Anidealinterfaceforuserswillhavethefollowingcharacteristics:
1. Beintegratedintohousingwatersupplyintheeventoflowcollectionlevelsa. Tie-intomunicipalpiping,tanklevelfeedbacksensor
2. Beproperlycombinedwithirrigationsystemfordistributiona. Soilsaturationsensor,dispersionnozzles
3. Bemicro-controlleroperatedandprovideeffectiveuserinterface;acceptsadesiredvegetationinputfromoperator
DESIGNFUNCTIONSANDSPECIFICATIONS
Whenitcametodeterminingfunctionsandspecifications,thegroupagreedthatthefunctionsmustinoneformoranothersatisfythefollowingconceptsofthedesign:
• Describewhattheproductdoes
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• Transformaninitialstate(input)intoadesiredfinalstate(output)• Useaseriesofmathematicalexpressionstocontroleachsystem
Whenconsideringproductdesign,itiscrucialthatthedesiredfunctionsoftheproductaredeterminedpriortoaspecificformofthedesignbeingselected.Inotherwords,whatthedesignistoaccomplishshouldbeidentifiedfirst,thenthewayitwillbeaccomplishedshouldbeconsidered.Inengineeringdesign,thefunctionisthetechnicalstartingpointoftheproject.Itsetsthetoneforwhatistobeultimatelyaccomplished.Howtheendstateistobereachedisthendeterminedthroughbrainstormingandresearchuntilaviablesolutionisfound.
Top-levelfunctions,majorsub-functions,andafunctionalblockdiagramwerecreatedtohelpillustratetheintendedpathforeachproject.
1. Identifyingthetoplevelfunction:
a. Thermostaticallycontrolledin-linefani. Reduceenergyconsumedtoheatandcoolahomeii. Use‘natural’heatandcooling(topfloorheat,basementcooling)iii. Controltheflowofairtomaintainasettemperature
b. Rainwatermanagementsystem
i. Reducerainwaterwasteii. Utilizewinterrunoffassnowmeltsinspring(collection,storage)iii. Controlthedistributionofwaterinanefficientway
2. InputsandOutputsofProjects:
a. Thermostaticallycontrolledin-linefan:
FIGURE1IN-LINEFANINPUTS/OUTPUTS
b. Rainwatermanagementsystem
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FIGURE2RAINWATERMANAGEMENTINPUTS/OUTPUTS
3. Sub-functionsoftheproject:
a. Thermostaticallycontrolledin-linefan
i. Abilitytoredirecttheflowofairtomaintainatemperatureii. Airfilteringandotherpassiveairqualitymanagementsystemsmayberequired
andaddedasneeded.iii. Variable control loop; the HVAC system should adapt to different set
temperaturesandcontrolsettings.
b. Rainwatermanagementsystemi. Ability tocontainwateraccording toclimateand location, thevolumeneeded
willmostlikelybeafunctionofthesefactorsplusothersii. Variable control loop, the rainwater management system should adapt the
differentinputparametersandcontrolsettings
4. FunctionalBlockDiagram:
a. Thermostaticallycontrolledin-linefan
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FIGURE3IN-LINEFANFUNCTIONALBLOCKDIAGRAM
b. Rainwatermanagementsystem
FIGURE4RAINWATERMANAGEMENTFUNCTIONALBLOCKDIAGRAM
5. Scientific&TechnologicalKnowledgeRequired
a. Thermostaticallycontrolledin-linefan
i. Controlmechanisms(Wandboard,USBCommunications)ii. FluidDynamics(Flow)iii. Thermodynamics(HeatExchange)
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b. Rainwatermanagementsystemi. FluidDynamics(Pumps)ii. ControlSystems(Wandboard,USBCommunications)iii. HorticulturalKnowledge(SoilConditions,Climate,YardConfigurations)
Basedontherequirementsdiscussed,acourseofactionalignedwiththemostimportantaspectsofeachprojectwasdetermined.Astheprojectcontinued,someoftheaspectsdescribedabovechangedwhileotherswereaddeddependingontheresultsofourresearchandtesting.Forexample,astheprojectprogressed,theIn-linefangroupdecidedtouseanArduinoUnomicrocontrollerinsteadoftheWandboard.Bothprojectswererathersimilarsothereweresomeopportunitiestoapplywhatwaslearnedinoneprojecttotheother.
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CONCEPTGENERATIONANDSELECTION
Designconceptsareideasthatsatisfythemajordesignfunctions.Thegenerationoftheseconceptsisthemostcreativeaspectoftheproject,asitrequirestakingafunctionandcreatingamethodofachievingthegoalsetoutbythatfunction.
Onceimportantdesignfunctionsweredetermined,possiblemeanswerethenestablishedtoaccomplishthefunctiongoals.Atotalofthreedesignconceptswerecreatedforthein-linefan,withminimalvariationsfromonetotheother.Creatingseveraldesignpossibilitiesallowedtheproblemtobeviewedfromanumberofangles.Thisway,theoptimalendproductcouldbeidentified.Initiallyitwasdeterminedthattemperaturecontrolwastobeachievedthroughtheutilizationofexistingtemperaturesourcesandsinks.Aswell,airexchangewouldtakeplacethroughforcedconvectioninnewductwork.Areductioninenergywouldbeattributedtoalargerallowedtemperaturedifferencebetweenthebasementandupstairs,meaningthefanwouldrunlessoften.Afiltercouldhavepossiblybeenadded,butatrade-offwasacknowledgedwhencomparingthebenefitsofthefiltertotheimpedanceonairflowandoverallperformance.Asforthecontrolsystem,theinitialapproachwastouseacombinationofaWandboardandMatlabprograming.However,anArduinoboardwoundupreplacingtheWandboardduetoitsavailabilityandeaseofcompatibilitywiththetemperaturesensors.
TABLE3RAINWATERMANAGEMENTMORPHOLOGICALCHART
RainwaterRelocationSystem
ContainLiquid BelowGroundmodularvessel
BelowGroundfixedsizevessel
AboveGroundmulti-vessel
Pond - -
DisperseLiquid Pump HydrostaticPressure CapillaryMethod - - -
MonitorVolume Massflowmeter “FuelGauge”
Sensor FloatStyle RadarSensor
ClimateData
-
CapturingRunoff
Strategiceavestroughplanning - - - - -
MonitorSoil MoistureSensor H20ConcentrationSensor ClimateData - - -
ControlMethod Wandboard Arduino RaspberryPi - - -
Program C++ Labview Matlab Arduino - -
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ContainmentofOverflow RainGarden MunicipalSewage OverflowTank Lawn Huge
Tank -
RelocationofOverflow ConcreteGutter
EavestroughTubing(Above
Ground)
UndergroundPiping(Below
Ground)
- - -
Basedontheabovemorphologicalchart,weareabletoidentifythedesignconceptsthatarebestsuitedtotherequiredfunctionofthesystems.Fortherainwatermanagementsystem,theconceptshighlightedindarkgreyaretheprimarymeansconceptualizedforthefunctionsrequiredandthetermshighlightedinlightgreyarethesecondarymeansforaccomplishingthefunction.
DEVELOPMENTANDDESCRIPTIONSOFDESIGNALTERNATIVES
Anotherwaytorepresentadesign’sbasicandsecondaryfunctionsandmeansisthroughafunction-meanstree.Thisillustrationismorein-depthandeachconceptismadeintoitsowntree.Therectanglesrepresentthefunctionsandthemeansaredepictedbytrapezoids.
FIGURE5RAINWATERMANAGEMENTFUNCTION-MEANSTREE
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FIGURE6IN-LINEFANFUNCTION-MEANSTREE
Usingthetwomethodslistedabove,threecomparabledesignsweregeneratedforeachcontrolsystem.
IN-LINEFANSYSTEM
1. Forcedconvection;existingductwork;largetemperaturedifference,usingsolarthermal;filteredair.
2. Forcedconvection;newductwork;improvedthermalefficiencyofhome;filterpadused.3. Forcedconvection;newductwork;usingsolarthermal;improvedthermalefficiencyofhome;no
filter.
RAINWATERMANAGEMENT
1. AboveGroundVesselwithWandboard,withoverflowtosewage,withscriptprogramming2. BelowGroundVesselwithRaspberryPi,withoverflowtank,withLabviewprogramming3. BelowGroundModularVesselwithArduino,withoverflowtoraingarden,withC++
Programming
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ASSESSMENTOFDESIGNALTERNATIVES
Conceptgenerationresultedwithanumberofworkabledesigns.Subsequentlythenextquestionwashowtopickthebestdesign.Thiswasdonebyclearlycommunicatingwiththestakeholderswhileatthesametime,incorporatingtheobjectivesandmetricspreviouslydefinedtobeofgreatimportance.
Weknewthatwithmanypossible-workingdesigns,itmightbeeasytolosedesigninsightsiftherewastoomuchinformation.Therefore,weacknowledgedthatitisgoodpracticetoevaluate3designconceptswith4-8selectioncriteria.Bothquantitativeandqualitativeinformationwasnecessarytocreateanadeptanalysis.
Throughtheuseofanumericalevaluationmatrix,weeffectivelyorganizedtheanalysisofthedesignconcepts.Theselectioncriteriaanddesignconceptswerelistedalongwiththeobjectivesandconstraintsoftheproject.Conceptsthatviolatetheconstraintswereeliminatedandtheremainderoftheconceptswereassignedscoresbasedondevelopedmetrics.
Belowarethenumericalevaluationmatricesforboththerainwatermanagementandin-linefansystems:
TABLE4RAINWATERMANAGEMENTNUMERICALEVALUATIONMATRIX
DesignParameter ObjectiveorConstraint?
Conceptnumber1
Conceptnumber2
Conceptnumber3
SustainPlantstopreventdying
C Good Good Good
Overflowthatprotectshouse
C Good Good Bad
EasilyInstalled O 90 60 -
UserFriendlyProgramming O 70 80 -
EasilyIntegratedHardware O 80 60 -
Totals: 240 200 -
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TABLE5IN-LINEFANNUMERICALEVALUATIONMATRIX
DesignParameter ObjectiveorConstraint?
Conceptnumber1
Conceptnumber2
Conceptnumber3
FastResponse C Bad Good Good
Thermostatic,AutomatedControl
C Good Good Good
Reliability C Good Good Good
CostControl O 100 100 50
EnergyUse O 0 100 50
Retrofitting O 0 0 0
AirQuality O 100 100 0
Totals: 200 300 100
Thescoresassignedtotheconceptsarebasedonthemarkingcriteriathatcanbeseenbelow.Thesemetricsaredevelopedbasedonthebest,worst,andintermediatescenariospossibleforeachdesignconcept.Themarkingcriteriaisasfollows:
TABLE6RAINWATERMANAGEMENTMARKINGCRITERIA
Score Installability Programming IntegratedHardware
100 2-Day Usedbynovice Cheapandeasytoconfigure
75 4-Day Usedwithmanual Expensivebuteasytoconfigure
50 6-Day UsedwithExternalResearch
Moderatelyexpensiveandmoderatelydifficulttoconfigure
25 8-Day Usedwithexpertguidingyou
Cheapbuthardtoconfigure
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0 10-Day Usedwithcoursetaken Expensiveandhardtoconfigure
TABLE7IN-LINEFANMARKINGCRITERIA
Score CostControl EnergyUse Retrofitting AirQuality
100 RelativelyCheap
<100Wdevices
Easilyinstalledonexistingwork
Principallyresponsibleforimprovinghomeairquality
50 SomeExpenses
100-1000Wdevices
Somecustomization Contributestoimprovinghomeairquality
0 MostExpensive
>1kWdevices Extensivecustomization Haslittle,no,ornegativeimpactonhomeairquality
Throughcompletionofthematriceswerealizedthatitisuncommonforadesignconcepttohaveaperfectscoreandbeawinnerinalloftheselectioncriteria.Thisgivesrisetotrade-offsthatmayrequireconsiderationaswellastheengineeringjudgmentsthatmustbemadetojustifythereasoningbehindthetrade-off.
Inthecaseoftherainwatermanagementsystem,thetrade-offsare:
• Theabovegroundvesseliseasytoinstallbutreducesstoragevolumeandmayfreeze• Labviewmaybeeasytocreate,butscriptcouldbemoreefficientandquickertorunwith
smallermemoryneeded
Basedontheabovetrade-offsandthenumericalevaluationmatrix,thefinaldecisionforthissystemhasbeenmade.WehavedecidedtouseanabovegroundvesselwithWandboardandscriptprogrammingbecauseithasagoodhardwareplatformthatgivesusalotofdevelopmentfreedomeventhoughwehavelimiteduseinthewintermonths.
Inthecaseofthein-linefansystem,thetrade-offswere:
• AirQualityvs.Performance:Betterairqualitycomesatthecostoffastresponsetime• Energyefficiencyvs.Performance:Thehighertheperformance,thehigherthepower
consumption,thelowertheefficiency• CostControlvs.EnergyEfficiency:Themoreenergyused,thegreatertheoperationalcosts
Basedontheabovetrade-offsandthenumericalevaluationmatrix,thefinaldecisionforthissystemwasmade.Wedecidedtouseaforcedconvectionsysteminnewductwork,withimprovedthermalefficiencyofthehomeandfilteredaireventhoughthefiltercostmoreperreplacement.However,asthisreportprogressesyouwillseeslightchangesthatoccurredincomparisontothesystemselectedabove.
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FINALDETAILEDDESIGN
OVERVIEWOFTHEDESIGNCONCEPT
IN-LINEFAN
Althoughtheconceptualdesignthatresultedfromtediousobjectiveandmetricconsiderationwasfundamentaltothein-linefanfinaldesign,slightchangesweremadeoverthedetaileddesignstageaswellastheprototypingstage.Intheend,thein-linefansystemconsistsofacolumnofductworkrunningverticallyfromthebasementfloortotheceilingoftheupperstory.Theducthousesareversiblein-linefaninside.Inanactualhome,ductoutletscouldbeplacedonthemainfloor,howeverthiswouldrequireabutterflyvalveandactuatortoredirectairflow;thiswasoutsideofthisproject'sscope.Theplacementofthisductisstronglydependentonindividualhomelayout,andmustbedeterminedbeforehand.Theductshouldideallybeplacedintheareawithgreatestflowdistributionpotential.ThesystemiscontrolledbyanArduinoUnomicrocontrollerthatreceivesindividualfloortemperaturedataintheformofvoltagereadings.Oncealargeenoughtemperaturedifferencebetweenfloorsisachieved,thecontrollerinitiatesthefanandairis,movedtothedesireddestination.
RAINWATERMANAGEMENT
Thedesignconceptwe’vechosentopursuecontainsanabovegroundstoragesystemthatiscomprisedofseveralvesselsthatareconnected.Thisallowsforeasyintegrationintohousesandyardsofdifferentsizes.Theirrigationsystemwillbecompletewithaproperlysizedpump,whichwillprovidethedrivingforceformovingthewatertowhereitisrequiredintheyard.Inordertocontrolwherethewaterwillbedirectedtherewillbezonevalvesthroughoutthenetworkofirrigationtubing,andineachzonetherewillbeasensormonitoringthesoil’smoisturecontent.Thecontrolsystemweplanonimplementingwillreceivethedatafromthesensorsaswellasthevolumeofwaterinthetank.Itwillthendeterminewhichzonesareinneedofwaterandhowmuchwaterisavailabletodistribute.Throughstrategicallyopening/closingthezonevalves,thesystemwillbeabletomaintainoptimalmoistureconditionsforseveraldifferentzones.
OVERVIEWOFKEYDESIGNCOMPONENTS
IN-LINEFAN
Thesystemhas3maincomponents.Firstly,therearetemperaturesensorswithoneplacedoneachlevelofthehometocapturerealtimeinformation.ThisallowstemperaturedifferencesinthehometobemoreaccuratelyrepresentedincomparisontothestandardHVACthermostat,whichtakesasingletemperaturereadingfromoneroom.Secondly,thereisareversiblefanplacedinsidetheducttoallowairflowtooccurinbothdirections.Thisreversibilityallowscoolbasementairtoberedistributedupstairsinthesummertimewhilealsoallowingwarmupstairsairtobecycledintothebasementduringthewintertime.Thirdisthecontrolsystemthatrecordsinputvoltagesfromthesensorsandoutputsavoltagetothefan.Thecontrolsystemisalsoaccompaniedbyagraphicuserinterfacethatallowsthe
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usertosetthedesiredtemperatureandacceptablerange.Theinterfaceallowstheusertocontrolthefanmanuallyifsoinclined.
RAINWATERMANAGEMENT
Thekeycomponentsrequiredtomakethissystemfunctionare:
1. Auserinterfacepromptingtheuserforcertainoperationalrequirements.2. Anirrigationsystemtailoredtothehomesyard.3. Properlysizedrainwaterstoragetank4. Moisturesensors(amountdependentonnumberofzonesandtheirsize)5. A control system capable of automatically distributing collected rainwater throughout a yard
basedontheuserinputs,moisturesensordata,andvolumeofavailablewater.
Theuserinterfacewillbewheretheuserinputsspecificinformationabouttheiryardsothatthecontrolsystemcanproperlymaintainit.Examplesofuserinputswouldbenumberofzones,typesofvegetationinthosezones,desiredwateringtimes,specialrequirements,etc.Ourprototypedidnotincludeauserinterface,asitscreationwasoutsideofourscope.
Theirrigationsystementailsallnecessarysuppliesneededfortransportinganddistributingrainwatertotheyard(pipe,pump,pressuretank,sprinklerheads,emitters,zonevalves,etc.).Thetypesandamountofsuppliesisdependentontheyardsizeandrequirements.Asimpleirrigationsystemwascreatedforourprototype.Itcomprisedofonepump,twosolenoidvalves,andtwomistingnozzles,whichwasallconnectedbytubing.
Theabovegroundstoragevesselsthatweareconsideringonimplementinghaveacapacityof50gallonseachandareabletobeinterconnectedtoincreasethestoragevolumeasnecessary.Therefore,fromacalculatedtanksizeofapproximately1000gallons,thishousewouldneedaround20vessels.Thesevesselscanbeorientedsothattheyfitbetweenthelatticeofafenceorunderneathadeck.
Themoisturesensorsareanintegralparttooursysteminthattheyprovidethefeedbackforourcontrol.Properlyinstallingandcalibratingthesensorsensuresthatthesoilwillbemaintainedaccurately.Asthenumberofzonesorthesizeofeachzoneincreasessodoestheamountofsensorsrequired.Thisistoensurethatthesoilmoistureiseffectivelybeingmonitored.
Thecontrolsystemwillbewhatiscontrollingthedistributionofwaterthroughoutthedifferentzonesintheyard.Byutlizingtheuserinputs,moisturesensordata,andvolumeofavailablerainwater,thesystemisabletocomputewhichzonesrequirewateringandthenstrategicallyopens/closesthezonevalves,aswellaspowersthemotor,untilthedesiredmoisturecontentismet.Forourprototype,thiscontrolsystemwillbecreatedonaWandboardandwillbeprogrammedusingPythoncoding.
PROJECTCOSTS
IN-LINEFAN
Althoughacomplete‘engineeringcostassessment’isnotpracticalatthisphaseoftheproject,acursorydiscussionofthecapitalandoperatingcosts,aswellasthefixedandvariablecomponentsofthelatter,
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willbeattemptedbasedonthebestavailableestimatestodate.Thecapitalcostsofthein-linefansystemarethemajorcontributortothelifetimecostsoftheentiresystem,sincetheenergythesystemintendstouseinordertomaintaintheclimateofthehomeisnaturallyoccurring.Capitalcostsmaybebrokendownintoengineering,procurement,andconstruction(EPC)costs.
Engineeringcostsarethoseassociatedwiththeinitialhomeassessmentandsubsequentdesignofthesystemtailoredtotheparticularhome.Thisprocesscouldbeexpectedtotakeonetotwodays,atwhichpointthepotentialhomeownerwouldbegivenanestimateoftheprocurementofmaterialsandconstructioncosts.However,notallcustomerspresentedwithestimateswouldbeexpectedtopurchasetheretrofit.Thereforethecostofengineeringisthevalueoftwodaysoftheengineers’timedividedbythehomeownerapprovalrate(theratioofthenumberofhomeownerspurchasingthesystemtothenumberofhomeownerscanvassed).However,amoreoptimalnumberwouldbeselectedbasedonthewillingnessofconsumerstopaytheengineeringfee,andthewillingnessoftheengineertoprovideservicesatthatprice.Thepricelistedfortwodaysofengineeringservicesusedinthisanalysisissetat$250.00.
Theprocurementcostsaresimplythecostsofthematerialsusedinthefinishedsystem.Thisisestimatedatroughly$500.00-$700.00basedonthecomplexityoftheinstallation.Thisfigureincludesthecostofthecontrolboard($50),wiring($20),thermocouples($30),reversiblein-linefan($200),ductwork($200),plustheoptionofaddingservo-controlledvents(4x$50).Thecostofthesematerialsarequantity-dependent,thereforethecostwouldbeexpectedtodecreasethegreaterthegrowthinconsumeradoptionrates.
Theconstructioncostsaresimplythecostsofthetimeofthetechniciansemployedtoinstallandcalibratethesystem.Althoughthespecifictimeandvalueofthetimeofthetechnicianscouldbeusedtocalculateaspecificvalue,oftenaconstruction‘multiplier’isusedtoestimatethisvalue.Sincetheinstallationmethodwouldnotbeuniversalforeachhome,arelativelyhighmultiplierof~3wouldbeappropriate.Themultiplierisappliedtotheprojectmaterialcosts.Thereforetheconstructioncostscouldbeexpectedtobebetween$1500and$2100.
Thetotalcostisthesumofeachofthesecomponents,andwouldthereforeberoughlybetween$2,250.00and$3,050.00.AdditionaluncertaintyexistsinthetotalEPCcostsduetothenon-standardnatureofhomes.Thereforeitisdifficulttoestimatewithanydegreeofaccuracytheexactcostoftheductingforeachprojectpriortoengineeringassessment.Ourgrouphavesettledonstatinganestimatedpriceofbetween$3,000.00and$4,000.00foragiveninstallation.
Theannualoperatingcostsarethosecostsassociatedwithfinancing,providingrequiredmaterialandenergy,andmaintainingthesystem.Thefixedoperatingcostsarethosethatarestaticacrossallpayperiods(usuallyoneyeareach),whilevariablecoststendtochangeacrosspayperiods.Duetothelowcapitalcostsofthesystem,financingwilllikelynotbeconsideredformosthomeownersunlessalineofcreditisused.However,thehighinterestratesassociatedwiththisapproachsuggestthatthisapproachwouldlikenotbefrequentlyused.Indeed,wesetthefinancingcostsat$0.Aswell,thein-linefansystemrequireslittleinthewayofmaterialorenergy,exceptfortheenergyrequiredtopowerthesensors,controlboardandfan.Thecontrolboardandsensorswouldtogetherconsume20Wofpower(afixedcost),whilethein-linefancouldbeexpectedtodrawroughly200Wonaverage(avariablecost),dependingonitsusage.Overonemonthofusagewherethesystemhasbeeninuseroughlyhalfthetime,thesystemwouldbeexpectedtouseroughly80kWh,andcouldthereforebeexpectedtocostthe
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homeowneramaximumof$12/mo.and$144/yr.,notincludingtheavoidedenergycostsassociatedwithstandardheatingandcooling.Aswell,wehaveallocatedanadditional$100/yearformaintenancecostsforthehomeowner,whichisalsoavariablecost.Thus,theexpectedoperationalcostsareexpectedtoberoughly$244/year.
RAINWATERMANAGEMENT
Thereisasignificantlyhighercostwhenitcomestothecomponentsfortherainwatermanagementsystem.Thisisduetotheconsiderationoffutureimplementationofthissystemintoaresidentialhousehold.Intotal,thetesting,building,andcompletionoftheprototypecameoutto$1025.09.AbreakdownofalltheindividualcomponentsandtheircostscanbeseenintheexpensereportattachedinAppendixA.Someofthemoremajorcomponentsthataccountforthemajorityofthecostarethemoisturesensors,theWandboardmicrocontroller,thesolenoidvalves,andtheirrigationsupplies.
MOISTURESENSORS
Forthepurposeofdemonstratingthedifferencebetweenseparatezonesinagarden,theprototyperequiredmorethanonesensor.Bearingthatinmind,thedecisionwasmadetobuy3moisturesensors.Atacostof$130persensor,thetotalcostofthesecomponentscametoapproximately$430.Consideringthehighpricepointofthesesensors,extensiveresearchwasdonebeforeorderingthem.Thereareavarietyofoptionsavailablewhenitcomestodetectingthevolumetricwatercontentofsoil,andtheyvaryinpricefrom$2-$300.ThedecisiontogowiththeEC-5sensorsfromDecagonDeviceswasbasedontheirrobustness,accuracy,andsimplisticintegration.Infact,whencomparedtohigherqualitysensorsthatofferaccuratereadings,theEC-5sensorsareoneofthemoreaffordableoptions.
WANDBOARD
ThenextsignificantcomponentoftherainwatermanagementsystemistheWandboardmicrocontroller.Cominginat$150,theWandboardisoneofthemoreexpensivemicrocontrollersonthemarket.WhencomparedtotheArduinoUNOusedforthein-linefansystem,whichcostsaround$50,itisevidentthattheWandboardisanexpensivechoice.Thejustificationbehindthispurchasestemsfromthefutureimplementationoftherainwatermanagementsystem.Moreover,theWandboardoffersanextensiverangeoffeaturesthatareunmatchedinmostmicrocontrollers.Forexample,theabilitytoprogramthecontrolsysteminPythonandimplementitontotheboardwasanimportantfeaturethatspeakstoabilityofthecurrentsystemtoberetrofittedintoaresidentialhome.Mostimportantly,theWandboardhastheabilitytobeaccessedviaWi-Fi.Theaddedbenefitofthisaccessibilityisessentialinthedevelopmentofanappfortheuser.Withthealreadyprovenpotentialofthissystemtosavetheusermoney,waterandtime,theemploymentofanappwouldallowcustomerstoselectthetypeofvegetationthattheyhaveineachzone.WithWi-Fi,thesystemcouldrespondandautomaticallycalibratethesensorstoreflectthetypeofplantthatisbeingwatered.Lastly,theabilitytologintotheWandboardviaWi-Fiallowsthesystemtobewireless,andcanbetweakedwithoutphysicalcontactwiththeboard.
SOLENOIDVALVES
Whenitcomestocontrollingthewaterflowtodifferentzones,thesystemrequirestheuseofseparateirrigationlines.Consideringthateachtypeofvegetationhasadifferentwaterrequirement,thecontrolsystemwillmakedecisionsbasedoneachindividualzone.Becauseofthisnature,thesystemrequires
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theuseofsolenoidvalvesthatcanoperateindependentofthepump.Thepurchaseof3ofthesevalvescostaround$68.Aftertestingandoperation,itwasfoundthatthesevalveswereabletomanagethedeliveryofwatertothezonethattheywereinchargeofbasedonthemoisturerequirements.
IRRIGATIONSUPPLIES
Evidently,alotoftheaforementionedsuppliescanbecategorizedastheelectricalcomponentsoftherainwatermanagementsystem.Tobeabletodemonstratethesystem’sfunctionality,aprototypewasbuiltusingalready-existingirrigationsuppliesfromHomeDepot.Thetotalcostofthesematerialswasapproximately$225anditincludeditemssuchas:irrigationhoses(1/4”and3/4”),hoseconnectors,PVCpipe,lawnsoil,spraynozzles,andapressurereducer.Withtheuseofthesecomponentsandseveralothersnotmentionedinthislist,asimplisticandeffectiveprototypewasdeveloped.Itwasusedtoemulatethedivisionofthegardenintoseparatezonesthatareindividuallycontrolledbythesystem.Amorein-depthdescriptionandoutlineoftheprototypecanbeseeninthe“VerificationandPrototypeTesting”sectionfoundbelow.
FEASIBILITYANDRISKASSESSMENT
IN-LINEFAN
Ananalysisofthefeasibilityofthissystemwhendeployedatfullscaletoprospectiveconsumersrequiresanobjectiveassessmentofthepromiseandtheperilofthesystem.Theformeristhatthein-linefansystemisintendedtosupplementexistingstandardHVACsystemsinAlbertahomesinordertosaveenergyandthereforegreenhousegasemissions.Inaddition,thesystemisfurtherintendedtobeofnetbenefittothehomeowner.Thelatteristhatthesystemisnotabletooffsethomeownercostsatall,andoursystem,whendeployedsimplyredistributesairwithinahouse,costingthehomeownercapital,andfailingtoprovidereductionsintheenvironmentalimpactsofhomes.Ourassessmentoffeasibilityatthisstageshouldbetakenaspreliminary.Althoughwewillattemptheretodeterminetheoverallfeasibilityofthesystemtothebestofourknowledge,thismaychangeasthescopeandcomplexityoftheprojectchanges.Bearingthatinmind,wewillbrieflydiscussfouraspectsoffeasibilityingeneralandwithrespecttooursystem:1)operational,2)technical,3)schedule,and4)economicfeasibility.
Operationalfeasibilityisaqualitativeassessmentoftheprojectedacceptanceofthesystembyconsumersandend-users,andconsistsofestimatinghowthesestakeholders‘feel’aboutusingtheproductinordertogaugehowwillingtheymightbetoacceptingit.Inaddition,itconsidersthe‘usability’oftheproductbyitsendusers.Consideringthelatterfirst,oneoftheprimaryconcernsofourprojectwastotaketheusabilityofthesystemintoaccountwhenconceivingthefinaldesignoftheproduct.Thein-linefansystemisdesignedtofunctionautonomouslyandeffortsweremadewithsuccesstoimplementauser-friendlygraphicalinterface,whichallowstheusertocontrolthepowerofthesystem,aswellastheoperationalmode(off,manual,andautomatic),temperaturesettingandsensitivity.Theautomaticmodeisdesignedtoprogrammaticallyminimizeenergyusagebythein-linefansysteminconjunctionwiththeexistingHVACsystemautonomously.Aswell,theGUIprovidesfeedbackoncurrenttemperaturesandfunctionalstatus,andfutureiterationscouldprovideanestimateofthereal-timeestimatedenergyandcostsavingsbeingprovidedbythesystem.
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Arealtimecostsavingsassessmentmayhelptomitigateapprehensionendusersmayfeelaboutpurchasingsuchasystem.Regardlessofthesuccessfulsimulationsanddemonstrationsoftheeconomicbenefitsofthesystem,usersarelikelytobehesitanttopayforaso-farunprovenproductwithhighercapitalcoststhantheirexistingHVACsystems(evenconsideringthedirectpaybackwiththedeclineinoverallHVACoperatingcostsduetotheenergysavings).Thebestapproachestoensuringthegeneralacceptanceoftheproductistoreduceanybarrierstoentry,includingreducingthecapitalcostsoftheproject,providingfreeengineeringconsultations,andcontinuallydemonstratingthesuccessfulcostsavingsinmodelhome.Finally,asinceredemonstrationofthepotentialofoursystemtomitigateenvironmentalimpactscausebyAlbertahomeswouldalsohelptoincreasethewillingnessofconsumerstospendthemoneyonourproduct.
Technicalfeasibilityconsistsofdetermininghowpracticalthesystemwouldbeandhowreadilyavailablethetechnicalresourcesandexpertisearetobuildandmaintainthesystem.Sinceoursystemconsistsprimarilyof‘offtheshelf’partsandisconfiguredsimilarlytoexistingHVACsystems,ittakesadvantageoftheexistingstandardmaterialsandtechnicalknowledgeofthisverymaturefieldofhomeHVACconstructionandmaintenance.Thein-linefansystemisexceptionallytechnicallyfeasible,andwasdesignedtobeso.TheinstallationprocedureandtimewouldbeidenticaltoretrofittinganyHVACsystemintoasingledetachedhome,beingbothinexpensiveandpracticallysimple.Theonlydifferenceswouldbethetuningofthecontrolsystemtosuittheengineeringassessmentofthethermalcharacteristicsofthehome.Sufficientnaturalheatingandcoolingmustbepresentinorderforthesystemtobeeconomicallyfeasible(moreonthatbelow),butcarefulconsiderationmustalsobegiventotheoptimalplacementoftheductinletsandoutlets(inordertomaximizetheresponsetimeofthesystemandnotdisturbthehomeowners).However,thesystemdoesnotrequireintegrationofhighpowerairconditionersormatingwithanaturalgasfurnace,andsoisroughlyequalintechnicalcomplexitywithstandardHVACsystems.
Schedulefeasibilityissimplythepracticabilityofanytimelineassociatedwiththeprojectgivenourcurrentstateofdevelopmentandthetimerequiredtocompleteanyremainingengineeringtasksandgoals.Typically,a‘feasible’scheduleissetatthebeginningofanyprojectbasedonthebestavailableknowledge.Thefeasibilityofthisscheduleisconstantlyreassessed,particularlywhenresolvingcrisesinthepredicteddevelopmentroadmap.Sincetheschedulewehavesetshouldbefeasible,wewillsimplyoutlinehereajustificationfortheoutlinesassociatedwiththisproject.First,weexpectthatadditionaltestingonfull-scaleprototypesdeployedtostandardfull-sizetesthomeswouldtakejustoverayear.Twomonthswouldberequiredtodevelopthemetricsnecessaryforassessinganygivenfullsizehomeandtestingthemonanumberofappropriatehomesandonemonthsforretrofittingofthein-linefansystemintotheexistinghomelayout.Additionallyafullyearoperationaltestingofthein-linefantodeterminebaselineperformanceandestimatesofexpectedcostsavings.Inthattime,supplychainfortherequiredpartswouldbeestablishedfordeploymentuponthesuccessfulconclusionoftesting.Basedonthedeploymentofsimilartechnologies(suchasothertypesofefficiency-basedretrofits)wecouldexpecttoseeaneventual5%annualgrowthrateinmarketaccess,andbuiltina10-year‘rampup’tothatgrowthrateatanincreaseingrowthof.5%peryear(seeResults–Figure11).
Finally,economicfeasibilityisaquantifiedmeasureofthecost-effectivenessofaproject.Thedeploymentoftheproductdependsmostheavilyontheeconomicfeasibilityofthein-linefansystemfromtheperspectiveofthepotentialconsumer.Agivenhomeownerwouldrequirethatthelifetimecostsofthenewin-linefansystembelessthanthatoftheproportionofHVACsystemitwillbe
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supplementing.Inparticular,theeconomicservicelifeofthein-linefan(includingallcapitalandoperatingcosts,aswellasthecostofborrowingtoinstallthesystem)mustbelessthanthatofthefractionofthesystemitisintendedtosupplement(or‘offset’).Thisrequiresthatthereliabilityofthesystempartsandintegratedcomponentsbereliableforarelativelylongtimehorizon(ontheorderof10to20years).Inaddition,afactorofriskovermustbeappliedtothein-linefanlifetimecoststoaccountfortheadditionallifetimerisktotheupfrontcapitalinvestedbythehomeowner,whocouldsufferloss.
Greaterthan95%ofAlbertahomes(particularlysingledetachedhomesofthekindtargetedasabenchmarkforthisproject)usehighefficiency(>90%)naturalgassystemstoprovideheatfortheirhomes.Aswell,onethirdofsingledetachedhomesinAlbertauseairconditioningforanaverageofsixmonthseveryyear(StatsCan,2012).Thepromiseofthesystemistooffsetsomeproportionoftheseenergydemandsbyusingtheavailableheatsourcesandsinksinthehomeinordertomaximizethatenergy-offsettingfactor.Fromtheeconomicperspectiveofagivenhomeowner,thesystemisfeasibleifandonlyifthenetpresentvalue(thatis,thesumofthesystem’stotalfinancialcostsandbenefitsoveradefinedproductlifetime)ofthenewinstallislessthanthenetpresentvalueofthefractionofexistingHVACsystemweoffset.Ourgoalwastherefore,toincreasethelifetimeofthesystemearlyinourdesignprocessbyusingafewercomponents,andensuringthatasmanycomponentsofthesystemcouldbepurchased‘offtheshelf’andthatthefewrequiredcustomcomponents(fanadapters,motorshields,andappropriatefittings,etc.)wouldhaveahighreliability.Thisgoalof‘designforsimplicity’hastheeffectofkeepingcapitalcostslow,andincreasingtheproductlifetime,bothofwhichincreasetheprobabilityofattractingconsumerstotheproductandoffsettingdirectenvironmentalimpacts.
RAINWATERMANAGEMENT
Similartotheanalysisforthein-linefansystem,thefeasibilityandriskassessmentcomponentsparalleleachotherinthatthepotentialviabilityofthesystemisalwaysfollowedbyapotentialhazardandasolution.Asoutlinedbytheobjectiveoftheproject,therainwatermanagementsystemisdesignedtoautonomouslymanagethevegetationinaresidentialhousehold,whilesavingthecustomermoney,water,andtime.Moreover,thesystemissustainablydesignedtoreducethewaterusagerequiredtoupkeepagardenwhileproducingoptimalplantsandvegetation.Themajorriskthatthesystemfacesisthatitdoesnotinfactsavethecustomerwaterandmoneyandproducesthesameresultasatypicalirrigationsystem.Thesecondaryriskisthatthereisnotmarketforthesystemanditdoesnotreceiveadoptionbythepublic.Inattemptingtoevaluatetheoverallfeasibilityofthesystem,wewilllookatfouraspects:operational,technical,schedule,andeconomical.Additionally,wewilldescribethecurrentsituationwithregardstothemarketadoptionoftherainwatermanagementsystem.
Aspreviouslydefined,operationalfeasibilityisaqualitativeevaluationoftheprojectedacceptanceofthesystembyconsumers,andconsistsofestimatinghowthesestakeholders‘feel’aboutusingtheproduct.Thisisusedinordertogaugehowwillingtheymightbetoacceptit.Additionally,itconsiderstheusabilityoftheproductbyitsendusers.Keepingthatinmind,oneoftheprimaryobjectivesoftheproductdesignwastoconsiderusabilityandfunctionalityforthecustomer.Thatis,therainwatermanagementsystemwasdesignedina“setandforget”mannersuchthatitwouldrequireaonetimesetupandtweakoftheparameters,andthenthesystemwouldoperateautonomouslywithouttheinteractionoftheuser.Tofurtherthedesignforusability,weusedamicrocontrollerthatiscapableofWi-Fiaccesssuchthatanappcouldbedevelopedinthefutureinordertoactasanadjustableuser
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interface.Thesystem’sabilitytooperateinthebackgroundandrequireminimal-to-noadjustmentbytheusermakesthesystemappealingtopotentialcustomers.Furthermore,thecategorizationofthissystemasasustainablechoiceforhomeownerstosavewaterandmoneyisamajorsellingpoint.
Arealtimecostsavingsassessmentmayhelpmitigatetheapprehensionendusersfeelaboutpurchasingsuchasystem.Regardlessofthesuccessfulsimulationsanddemonstrationsoftheeconomicbenefitsofthesystem,usersarelikelytobehesitanttopayforanewproductwithhighercapitalcoststhantheirexistingirrigationsystem.Thebestapproachestoensuringthegeneralacceptanceoftheproductistoreduceanybarrierstoentry.Thisincludesreducingthecapitalcostsoftheproject,providingfreeengineeringconsultations,andcontinuallydemonstratingthesuccessfulcostsavingsinamodelhome.Finally,asinceredemonstrationofthepotentialofoursystemtomitigateenvironmentalimpactscausebyAlbertahomeswouldalsohelptoincreasethewillingnessofconsumerstospendthemoneyonourproduct.
Movingontothetechnicalfeasibilityoftherainwatermanagementsystem,itisimportanttolookathowpracticalthesystemwouldbeandhowreadilyavailablethetechnicalresourcesandexpertisearetobuildandmaintainit.Becauseoursystemcontainsamajorityof‘offtheshelf’partsalongwithintelligentprogramming,ittakesadvantageofexistingstandardmaterialsinthefieldofagricultureandirrigation.Likewise,thereareamajorityofhouseholdsthatcurrentlyhavesomesortofanirrigationsysteminstalled.Itisforthesetworeasonsthatthetechnicalfeasibilityofthisdesignisexceptional.Installingtherainwatermanagementsystemwouldbesimilartotheinstallationofregulararegularirrigationsystemintoaresidentialhousehold,beingpracticallysimple.Therearetwodifferencespresentbetweentheinitialsetupoftheaforementionedsystems.Thefirstisthehigherinitialcapitaloftherainwatermanagement.Becausethesystemisintelligentinitsabilitytocontinuallymonitorsoilmoistureandprovidefeedbacktothedifferentzones,therearesomeadditionalpartsnotfoundintypicalirrigationsystems.Thisisthedrivingfactorforthehigherinitialcapitalinvestmentofimplementingourdesign.Secondly,thetuningofthecontrolsystemisrequiredpriortoitsautonomousoperation.Whatthatlookslikeissimple:theusermustenterthetypeofvegetationineachzoneoftheirgardensuchthatthesystemcanupdatethewaterrequirementsmeasuredbyeachsensor.Onceanappisdeveloped,thisprocesswillbeassimpleasopeningtheappandselectingthetypeofvegetationfromadrop-downmenu.
Schedulefeasibilitysimplyreferstothepracticalityofthetimelineassociatedwiththeprojectgiventhecurrentstateofdevelopmentaswellasthetimerequiredtocompleteanyremainingengineeringtasks.Uponbuildingaprototypeandtestingourproofofconcept,wewereabletovalidatethefunctionalityofthesystemanditsabilitytointelligentlydecidewhenaplantneedswaterbasedonthesoilmoisture.Basedonthecurrentprototype,thepossibilityforoptimizationhasbeenidentifiedandisnecessary.Totrulyensurethatthissystemisreadyfordeployment,thereisaschedulethatneedstoberespectedtoensureasuccessfulresult.First,weexpectthattheoptimizationphasewouldlastforapproximately2months.Whilethatistakingplace,thedevelopmentoftheappwouldbeinprocessandwouldcontinueforanothermonthortwoafterwards.Uponthecompletionoftheappandoptimizationprocesses,anadditional2monthswouldberequiredfortestingandcalibrationofthesystem’sparameters.Inthattime,supplychainfortherequiredpartswouldbeestablishedfordeploymentuponthesuccessfulconclusionoftesting.
Lastly,economicfeasibilityisthequantifiedmeasureofthecosteffectivenessofaproject.Theimplementationofthisproductdependsmostheavilyonitseconomicfeasibilityfromtheperspectiveof
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apotentialconsumer.Agivenhomeownerwouldrequirethatthelifetimecostsoftherainwatermanagementsystembelessthanthatofanirrigationsystemwithallofitsinefficiencies.Inparticular,theservicelifeofthesystemmustbeaccountablesuchthateconomically,itcostslessthantheamountofsavingsitisoffsettingfortheuser.Thisrequiresthatthereliabilityofthesystempartsandintegratedcomponentsbereliableforarelativelylongtimehorizon(ontheorderof10to20years).Withthepromiseofthesysteminmind–toeliminatetheinefficienciesofirrigationsystemsandsavethecustomermoneyandwater–thesystemiseconomicallyfeasibleifandonlyifthenetpresentvalueislessthanthefractionofmoneysavedbyoffsettingtypicalwaterconsumption.Ourgoalwasthereforetoincreasethelifetimeofthesystemearlyinourdesignprocessbyusingfewercomponents,andensuringthatasmanycomponentsofthesystemcouldbepurchased‘offtheshelf’.Thisgoalof‘designforsimplicity’hastheeffectofkeepingcapitalcostslow,andincreasingtheproductlifetime,bothofwhichincreasetheprobabilityofattractingconsumerstotheproductandoffsettingdirectenvironmentalimpacts.
Lastly,feasibilityfromthepointofviewofmarketadoptioniscrucial.Aswithanynewproduct,thereiscompetitionfromsimilarproductsaswellasthecompetitionoftheproductnotbeingadoptedbythemarket.Althoughnotpartoftheprojectrequirements,ourgroupfounditnecessarytoaddresstheissueofmarketadoptionthroughmarketresearch.UpongettingincontactwithLeafandLyre–aspinfarmingbusinessinCalgary–wewereabletoidentifyaninterestinourcurrentsystem.Inthesimplestofterms,spinfarmingisasustainablemovementthattakesproductivityandprofitabilityofahomegardenlottothenextlevel.Moreover,spinfarmersuseplotsofspaceinresidentialhomeowner’sgardenstogroworganicproduceforsalebacktothecommunity.Notonlydoesthismovementsupportthelocaleconomy,butitalsotacklestheissueofsustainabilityinarapidlygrowingpopulation.BasedonthemeetingwithLeafandLyre,wewereabletoreceivemarketvalidationwithregardstoourproduct.TheCEOofthisspinfarmingventureinCalgarywasintriguedbytheideaofthesystemandsawfullpotentialinitsbenefits.Hisinvolvementintheglobalspinfarmingmovementallowedhimtospeakonbehalfofthecommunitywhensayinghowusefulthesystemwouldbe.Notonlydoesitproduceoptimalvegetation(whichisoneoftheaimsofaspinfarmer),butitalsosaveswaterandfocusesontheglobalissueofsustainability.Thesignificanceofthismeetingisevident–ourgroupwasabletovalidatethedesignconceptoftherainwatermanagementsystemwhilefindingamarketfordeploymentinadditiontothetargetmarket(residentialhomeowners).
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VERIFICATIONANDPROTOTYPETESTING
IN-LINEFAN
Althoughthemajorityofourprototypetesting,simulationandscenariomodelingwerecompletedthroughmultipleiterationsratherthansequentially,thetestingresultsdiscussedinthefollowingsectionwillbepresentedlinearlyaccordingtothelevelofanalysis.First,fundamentalcomponenttestingwascompletedtoensurethateachpartofthesystemwascapableofmeetingourbasicdesignconstraintsandalsotoseehowmuchfurtherwecouldpushthecomponentsifnecessary.Forinstance,weneededtoensurethatthetemperaturesensorsprovidedatleast1-2degreesCelsiusofresolutioninpractice,butwealsohopedtohavemoretoimprovetheresponsivenessofthesystem.ThenextlevelofanalysiswastosimulatetheflowenvironmentinSolidWorkstoensureoursystemcouldreasonablychangethetemperatureofourtargetfloorpriortomodelingthatenvironmentwithaphysicalprototype.Wethenmeasuredtheabilityofthephysicalprototypein-linefansystemtomodifythetemperatureofthe1/20thscalemodelhomecomparedtonaturalconvectionandconductionheattransfer.ThetimeresponseresultsofthephysicalmodelwereusedtoprovideconstraintsontheresponsetimeofaSimulink-basedmodelofthehomeinordertomodelthepotentialenergysavingsofthesystemduringdifferentseasons.TheenergysavingswereusedtoestimatethepotentialcostsavingsinSimulink.Finally,scenariomodelingusingWhatIf?TechnologiesCanadianEnergySystemsSimluator(CanESS)wasusedtoderiveanestimateofthepotentialgreenhousegasemissionsreductionsasthesystemisdeployedtohomesacrossAlberta
COMPONENTTESTING:
ThefirsttestsoftheTMP36temperaturesensorassessedthevarianceinthetemperaturemeasurement,andqualitativelyassessedtheresponseofthetemperaturesensortosimplechangesinlocaltemperature(Figure3).Thetemperature'noise'wasroughly+/-0.5degreesCelsiusandisthereforeacceptableforuseinourapplicationwheretemperaturechangesareexpectedtobebetween1and20degreesCelsius.
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FIGURE7CHARACTERIZATIONOFTMP-36TEMPERATURESENSORPERFORMANCE
Totestthestabilityofthetemperaturesensor,temperaturedatawascollectedwhilebeingsubjectedtolowfrequency(10Hz)vibrationaswellashighairflowconditions(~20cubicfeetperminute;Figure8).Thedatawerereplicated(n=7)andwereanalyzedusinga2x2ANOVAwithTukey’s‘honestlysignificantdifference’post-hocmultiplecomparisontests.Vibrationcausedasignificantdropinthetemperaturerecordedbythesensor.However,aneffectofincreasedairflowwasnotobserved,norwasaninteractionbetweenthetwofactorsobserved.
FIGURE8EFFECTOFAIRFLOWANDVIBRATIONOFTMP-36RELIABILITY
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CONTROLSYSTEMLAYOUTANDDESIGN
Abasiccontrolsystemforoperatingthein-linefanwasdesigned(Figure9,10,12)toreadthetemperaturefromthreelocations:1)thetopfloorwhereheatfluxintothesystemgeneratedbyahotairsourcewillbereadbythetopfloorsensor,2)themainfloor,and3)thebasement,wherecoolertemperaturesgeneratedusingdryice(~100gramspertrial)wouldresultinheatfluxoutofthesystem,simulatingaheatsinkforthehome.Theusercouldsetthetemperatureonanyfloor.ThecontrolboardisanArduinoUnoplatformcontrolledbyandprogrammedusingtheMATLAB'ArduinoIOpackage'.Thephysicalcontrolsystemaspresent(Figure9,appliedtoprototypeinFigure11)consistsoftheArduinoUnoPCBwhichreadstheanalogtemperature-dependentvoltagefromthreeTMP36analogtemperaturesensors,eachofwhichiscalibratedpriortouseinthecompletedcontrolsystem.TheArduinodisplaysthetemperaturesinthePC-baseduserinterface(Figure12).Thethermostatsystemthendecidesontheappropriatefansettings(power,fanspeed,anddirection),whichwouldmosteffectivelyandinexpensivelyprovidethedesiredhomeenvironmentconditions,andappliesthosesettingstotheappropriatelydirectedfan(Figure10,11,14)
FIGURE9.CONCEPTUAL(LEFT)ANDPHYSICAL(RIGHT;ARDUINOUNO)LAYOUTSOFINLINEFANCONTROLSYSTEM
ThesystemconsistedofthreeinputTMP36sensors(smallblackunitsmountedinparallelonthebreadboard)whichsendanalogvoltagesignalsreadbytheArduinoUnoboard,anAdafruitV2.3MotorShieldconnectingtworeversiblePCfanstotheUnoboard.RealtimetemperaturedataandDCmotorstatuscanbeoutputandcontrolledthroughaMATLAB-basedinterfacedesignedusingMATLAB’sgraphicaluserinterfacedesignenvironment(Figure12).
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FIGURE10.CONCEPTUALDIAGRAMOFTHECOMPLETECONTROLSYSTEMOFTHEINLINEFANSYSTEM
FIGURE11.BASICTHERMALMODELOFASTANDARDHOMEWITHANINTEGRATEDINLINEFANSYSTEM.
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Figure11demonstratesabasicthermalmodelofastandardthree-storeysingledetachedhomewithanintegratedpassivesolarandgeothermalinlinefansystem.ThismodelwasbasedonthesamehomemodeldevelopedforuseintheSolidWorksflowandtemperaturemodelingsystem,andwasthebasisfortheconstructionofthephysicalprototype,andthethermalmodelsofthesamehomeintheSimulinkmodel.Ontheleft-handsideofthefigure,thebasicheattransferpathwaysaredefinedforthethermalmodelofthehomeandeachfloor,withheatdefinedasflowingintothehomethroughtheroof,fromhigherfloorstolowerfloors,andoutthroughthebasementfloor.Heatisalsolostthroughtheinsulatedwallsoneachfloor.Thisestablishesadiscretetemperatureateachfloorandathermalgradientbetweenfloors(suchthatT3>T2>T1).Aswell,thermalmasses(Cth1,2,3)arepresentoneachfloor.Theinlinefansystemisshownasacolumnwithinletsandoutletsandacentralizedfan.Inthisinstance,theairflowisshownasbeingdrawnfromthefloor1(thebasement)anddirectedtothetopfloor.Thermostatsmaybesetselectivelyoneachfloor(shownontherighthandside)withthesettemperatureoneachbeingsetbytheuser.Ourbenchmarksettemperaturewassetat20+/-1degreeCelsiusforalltestingascloselyaspossible.Outputs(inheavyarrowsleavingthehome)areshownontherightside,andconsistofthetemperaturemeasuredforeachflooraswellasthesettemperaturedesiredbytheuser.
Formal‘testing’ofthissystemhasconsistedofestablishingaseriesoffunctionalprototypeseachmorecomplexthantheprevious.Priortobuildingacontrolsystem,whichcouldeasilycontrolaductfanbasedonenvironmentaltemperatures,theconnectionandoperationofeachcomponenttothecontrolboardthroughsoftwarehadtobeestablished.First,theconnectionofthetemperaturesensorswasperformedandusedtoreadthetemperatureinrealtime.Earlytestingofthissystemwasdirectedtowardsdecreasingthecomputationtimeofeachcontrolsystemloopinordertoincreasetheeffectivesamplingrateofthetemperatureonthesoftwareside.Next,aplotdisplaywasdevelopedtocontinuouslydisplaythetemperaturesimilartothestyleofanoscilloscopeinone-minutesweeps.Followingdebuggingatthisstage,theabilityofMATLABtocontrolatwo-wayvariablespeedDCmotorwasestablished.First,themotorwasattachedthecircuitboardprotectedwithaMOSFET-basedsystemtopreventvoltagefromtheback-emfofthemotordamagingthecontrolboard.FollowinganumberofMOSFETfailures,anofficial‘motorshield’designedbythethird-partyArduinodeveloper‘Adafruit’waspurchasedandwasabletoprovidestableconnectivity.Next,additionaltemperaturesensorswereintegratedintothedesignandprogrammedintothecontrolsoftware.
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FIGURE12USERINTERFACEANDSYSTEMDISPLAY
Figure12illustratesascreencaptureofthesystemdisplayandcontrolinterfacedesignedusingMATLAB’sgraphicaluserinterface(GUI)designenvironment(GUIDE).TheGUIconsistsofthermostatcontrolsintheleft-handpanelwithpowerswitches,settemperatureinputs,andmasterfancontrols('off','manual',and'automated').Intheright-handpanelisarepeatingminute-longchartoftemperaturereadingsalongwithalegenddisplayingthecurrenttemperature,aswellasthe‘power’,‘direction’and‘speed’statusofthein-linefansinthebottomleftcorner.
Oncethesecomponentswereshowntobeabletostablyreadtemperaturesoverareasonableoperationalrangeandusethatinformationtoacontrolafan(thecontrolsystem‘backend’),amorepolishedgraphicaluserinterface(GUI)wasdesignedtoallowmoresimplecontrolofthesystem(Figure6).FunctionswereprogressivelyaddedtotheGUIonceastable,functionalversionhadbeendebuggedandtestedateachstage.OncetheGUIhadbeensufficientlyrefined,aprogramdesignedtorunindependentlyontheArduinowithoutconnectiontothePCwasdesignedusingfirsttheMATLAB-basedenvironment,andtheninthelower-levellanguageoftheArduinointegrateddevelopmentenvironment(IDE)inordertoprovideseveraloptionswithwhichtoprogramthefinalversionofthecontrolsystem.
PHYSICALPROTOTYPETESTING
Inordertoensuretheprototypein-linefansystemwascapableofusingthenaturallyavailableheatsourcesandsinkstocontrolthetemperatureofthehome,wecompleted'proof-of-concept'experimentstodemonstratethatpotential.Asaninitialbenchmark,weassumedtheuserwouldsetthetemperatureofthetopfloorofthehometo20+/-1degreesCelsius.Thebottomfloorwasinitiallycooledto11degreeswhilethetopfloorwasheatedto35degreesusing45secondsofhotairflowdeliveredwithahairdryeron'High'.Wemeasuredtheabilityofthein-linefantomodifythetemperatureintwomodes:an'AB'experimentalmode,anda'BA'mode.IntheABmode,thefloorwasallowedtocoolnaturally('A')andthetimeconstantofthesystemtoreachitssteadystatewasmeasured,thenthein-linefansystemwassetto'automatic'andallowedtocoolthetopfloor(Figure11,12).Thenaturalcoolingofthefloortook335secondstodrivethetemperaturedown63%measured
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fromitinitialstatetothesteadystate(user-set)value(Figure11,'FanOff')andthein-linefansystemprovidedadditionalcoolingpowerevenasthetopfloorslowlyreachtheasymptoticsteadystatevalue.IntheBAmode,thein-linefansystemwasinitiallysetto'automatic'andallowedtocoolthefloor,andthetimeconstantofthesystemtoreachitssteadystatewasmeasured,thenthein-linefansystemwasturnedoffandthetopfloorallowedtotransferheatnaturally(Figure13).Thein-linefansystemdroppedthetimeconstantmeasuredbyroughly50%to160seconds(Figure13,'FanOn'),andthethermalmassofthesystemcanbeseenreleasingheatbackintothetopflooroncethefansystemwasturnedoff(Figure13,'FanSystemOff').Thisdemonstratesthatthein-linefansystemisabletooperatemuchbetterthannaturalheattransferprocessesandcompareswellwithstandardHVACresponsiveness.Thus,thein-linefansystemwouldbeexpectedtoreliablyprovideheatingandcoolinginthepresenceofsufficientnaturalheatsourcesandsinks.
FIGURE13RESULTSOFOPERATINGIN-LINEFANSYSTEM
Figure13demonstratesthebasicabilityofthefansystemtocontrolroomtemperatureinthephysicalprototypebydirectingairfromtheheatsink(thebottomfloorwithdryice)totheheatsource(thetopfloorwithheatedair)testedempiricallyintwomodes.(a)First,thehomewasheatedto35degreeandfirstallowedtocoolnaturally,andthenthefansystemturnedontoimprovetemperaturecontrol.(b)Secondandconversely,thehomewasagainheatedandthefansystemturnedontocoolthehome,thenthehomewasallowedtocoolnaturally.Thetimeconstantofthetemperatureresponse(measuredasthetimetoreach63%ofthesteadystatecondition)decreasedsignificantlybyhalfwhenthefansystemwasengaged.
SIMULATIONS–SIMULINKANDSOLIDWORKS
FIGURE14SOLIDWORKSMODELSIMULATIONS
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Theconvectiveflowmodelofafull-sizedhomewasdevelopedinordertodeterminetheflowcharacteristicsofastandardhomeandrationalizewhetherthein-linefansystemwassufficienttogeneratetherequiredinternalflowandachievethenecessaryenvironmentalconditions(Figure12).Itwasdeterminedthatafullscale10”fanwithstandardvolumetricflowrateswassufficienttogeneratecirculationinthehomeinwellunder30minutesbasedonthefan'sflowrateandthehouse'stotalvolume.Thiscouldbeachieveddespitetheeffectsofnaturallyoccurringconvectiveflowinducedbytemperaturegradientswithinthehome.TheSolidWorksmodelwasalsoscaledappropriatelyusingthismodelfromafullsizemodelwith8and9-footceilings(Figure13),toa1/20thscalemodelwith0.4ft.and0.45ft.ceilings(Figure14).
FIGURE15FULLSCALEHOME-SOLIDWORKSMODEL
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FIGURE16CUT-AWAYOFDUCTAT1/20OFSCALE
Thehousewasmodeledbasedonstandardmeasurementsofthemodernhome.Thisincludedwallthicknesses,ceilingheight,androomsizesforexample.Withanactualhouse,wecouldsimulateflowpatternsandthermaldistributionsusingSolidWorks.Thispreliminarytestingallowedustodeterminewhatdimensionswerefeasibleforourin-lineductingtohave.Thesimulationalsoshoweduswhatvelocitiesofairwecouldexpectwithinthehomewhilethesystemisrunning.Thiswasimportantsinceairflowsthataretoohighcancausediscomfortfortheresident,butairflowsthataretoolowdonotofferanycirculatory/airexchangeeffects.Thesimulationallowedustotweakourduct-openings,aswellastheorientationoftheduct'slocationinordertooptimizebothair-exchangeandair-velocityinthehome.Theresultswerepromisingaswecoulddemonstratethatthetopfloor'stemperaturecouldbedroppedby~8degreesCelsiusinlessthan25minuteswhenairispulledfromthebasement.Thissimulatedmodelwasaspringboardfromwhichwecouldcompleteadditionaltasksdowntheline.
Two'Simulink'-basedthermalmodelsofstandardAlbertahomes(onewithastandardHVACsystem,andonesupplementedwiththein-linefansystem)wereconstructedusingthetimeresponsivenessderivedfromthephysicalprototypeinordertodeterminetheenergyandcostsavingspotentialofthesystemfortypicalhomeownersinAlberta.Thetemperaturemodelsofbothsystemswerebasedonasinusoidaltemperatureinputwithanoffsetof16degreesCelsius(theaveragetemperatureforourbenchmarkmid-SummerdayinAlbertabasedondatafromRETScreen'shistoricaldatainAlbertain2014),a24-hourperiod,andpeak-to-peakamplitudeof20degreesCelsius.Bothhomemodelsconsistedofthermalmodelsofthetop,main,andbottomfloor(Figure17,middlegraphsofbothpanels),basedonthetemperatureinputs,athermostat/relaycontrolsystem,thehome/furnace/ACactingastheplantandthemainflooractingasthesystem.Temperatureswerereadusingideal
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thermocoupleswithnointernalfirstorderdynamics.Thestandardhomeoperatesnormally,providingheatintheeveningwhenthefloortemperaturedropsbelowthesetpoint,andairconditioningwhenitgoesabove(Figure17,leftpanel).Thetotalenergycostsforthestandardhomeusinganaturalgascostof$2.50permmBTUandanelectricitycostof$0.15/kWhtotalledapproximately$6.25/2daysoffunctioningnormally(equivalenttoroughly$1,000.00to$1,200.00forhomeheatingandcoolingenergyannually).
Thealternativemodelofthehomeincludedathermostatwhichwoulddecidewhentousethein-linefansystem,shuttingofftheexistingHVACsystemtodrawonlyonpoweravailablefromthenaturalheatsourceorsink,asrequiredifavailable.Atleast4degreesoftemperaturedifferenceisrequiredbetweenthesourceorsinkandthefloorwiththesettemperatureinordertodrivethetemperaturetoitssetpointinareasonableperiodoftime.Thetotalenergycostsforthealternativehomeusedthesamepowercostsasthestandardhome,totalingapproximately$4.10/2daysoffunctioningnormally(theequivalentofroughly$750.00-$850.00forhomeheatingandcoolingenergyannually).Additionally,therequiredairconditioningpowerwasalmostentirelyeliminatedinthisscenario.
Figure17showsresultsfromtheSimulink-basedmodelofastandardAlbertahomes(left)andahomewithanin-linefansystemsupplementingastandardHVACsystemoveratwo-dayperiod(right).Topgraphsshowtheon/offstateofthefurnace/ACforthetopfloorandbottomfloorflow.Middlegraphsshoweachfloor'stemperature(topfloorinred,mainflooringreen,basementfloorinblue).Bottomgraphsshowtheinputenergycosts(naturalgasinred,electricityinblue,andthetotalinblack).
PROTOTYPEDESIGNANDMANUFACTURING
Theinitialprototypedesignconsistedofa6ft.tall,6in.diameterductwithareversiblefanhousedinside.Thermocouplesweretobeplacedateachendoftheducttocapturetemperaturedataasairenteredandexitedtheduct.Acontrolsystemverysimilartotheoneactuallycreatedwouldreceivevoltagereadingsfromthermocouples,thenapplyavoltagetothereversiblefanmovetheairasneeded.Toproperlyscalethisprototype,itwassuggestedthatthe6in.fanbeoperatedatsuchaflowrateastokeeptheReynolds’snumberidenticaltothefull-scalesystem(10in.fan).Thispreliminaryprototypedesignwouldeffectivelyshowcasethecontrolsystemsincethetemperaturedatacollectedwouldresultinthefanmovinginadesireddirection.However,itwasdeterminedthatotherusefultestingdatamay
FIGURE17RESULTSFORSUPPLEMENTATIONOFANHVACSYSTEMWITHTHEIN-LINEFAN
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notbesuccessfullyrecoveredfromsuchamodel.Forthatreason,amoreholisticprototypewasconceptualizedandimplemented.
Itwasacknowledgedthatasuccessfulprototypewoulddisplaynotonlyeffectivecontrolsystemimplementation,butalsoeffectiveairflowandtemperaturedistributioncapabilities.Forthesereasons,theprototypeapproachchosenwastobeascaleddownversionofthehousesimulationbuiltinSolidWorks.Thisclosedsystemwouldallowairexchangetooccurandmeaningfultemperaturevaluestobecollected,whilebeinganaccuraterepresentationofthefullsizesystem.Aftercarefulconsiderationandplanning,thehouse-scalingfactorwasdeterminedtobe1:20;thismadetheprototype'ssizeroughly2ft.widex1.5ft.deepx2ft.tall.Sincetheprototypewasascaledreplicaofthesimulationmodel,datacollectedduringtestingcouldbedirectlycomparedwiththesimulationresults.
Theprototypeconsistsofthreestories,eachidenticaltotheSolidWorksmodel.Theinteriorwallsandstaircaseswereincludedtohelpreplicatetheexactflowdistributionsproducedinthesimulations.Allwalls,floors,andstairsweremadeof3/4in.Plexiglassincethismaterialwaslightweightandallowedustoviewtheinsideofthehouse.Thisfeaturecomesinhandywhentryingtovisualizetheairflowwiththeassistanceofdryice.Also,thePlexiglascreatesamoreatheisticallypleasingprototypefortheaudience,andmakesexplainingthefunctionalityoftheprototypeeasier.Tosimulatetheductairflow,2in.PVCpipingconnectsthetopandbottomfloorswiththeassistanceoftwo90-degreeelbows.Twosmallfansarelocatedhalfwayuptheductandareplacedbacktobacktosimulatereversibleflow.Initiallyonlyonefanwastobeused,andreversibleflowtobesimulatedbyinvertingthevoltagesonthefan.However,thefanburnedoutafterrunningintheoppositedirectionsothisoptionwaseliminated.Thefansareheldin-linewiththeductusingtwocustommadeadapters.Theadaptershouseandsandwichthefansbacktoback,andaremechanicallymatedthroughtheuseoffournutsandbolts.
Mountedtothefanhousingisthecontrolsystem.TheheartofthesystemistheaforementionedArduinoUnoboard.TemperaturesensorsoneachlevelrundirectlytotheArduinoinputpins,whereMatlablogicinterpretstheinputvoltagesandoutputsadesiredvoltagetotherequiredfan.Tomaketheprototypemorerealistic,thermalmasseswereaddedonthetopandbottomfloors.Thesemasses(sheetsofmarbletile)absorbenergysimilartofurnitureandotherhouseholdbelongings.Thisenergycanthenbereleasedtothesurroundingswhentemperatureschangeinthevicinity.Alltogethertheprototypesuccessfullyredistributesairwithinthehomewhenatemperaturesinkandtemperaturesourcearepresent.
PROTOTYPETESTING
Withafullyfunctionalprototype,thenextstepwastestingthemodel.Acrucialaspecttotestingthein-linefansystemwascreatingalargetemperaturedifferencebetweenthetopfloorandthebottomfloor.Thisneededtobedonetosimulatethenaturaltemperaturegradientthatformsineveryhome;thewarmairtrappedupstairsandthecoolairresidinginthebasement.Thelargestproblemwasfiguringoutexactlyhowtocreatesuchalargetemperaturedifferenceinsuchasmallspace.Theteamsuggestedperhapsconductivelyheatingthetopfloorwithaheatingpad,andconvectivelycoolingthebottomfloorwithcoolair.Thiswasagoodstartingpoint,butitwaseasytoseethetimerequiredforbothoftheseprocessestoeffectivelyaddandremoveenergyfromthesystemwouldtakefartoolong.Thenextlogicalstepwastoblowwarmairintothetopfloorandtosubmergethebasementintoanicebath.Boththeseapproachessignificantlyreducedthetimeittooktoincreasetheupstairstemperatureandto
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decreasethebasementtemperature.However,blowingwarmairdirectlyintothesystemwasmuchfasteratreachingthedesiredtopfloortemperatureincomparisontothetimeittooktheicebathtoreachthedesiredbasementtemperature.Tobeprecise,ittookmerely45secondstowarmtheupstairsfloorto35degreeswhereasittookcloseto15minutesfortheicebathtoreducethebasementto10degrees.
Itwasn’tuntildryicewaspurchasedtoshowflowdistribution,thatitscoolingpotentialwasrealized.Theendothermicreactionabsorbedenergyveryquicklyfromthebasementenvironment.Usingroughly100gofdryicedroppedthetemperaturedownto10degreesinminutesandkeptitsteadythroughoutthetesting.Withtheabilitytoestablishalargetemperaturedifferenceeasily,multipletestscouldberunefficientlyandeffectively.Tophysicallytestthesystem,twotrialswererun.First,theupstairsfloorwasheatedto35degrees,thebasementwascooledto10degreesandthesystemwaslefttoredistributethetemperaturedifferenceonitsown.Temperaturedatawascollectedevery30secondsfromboththetopfloorthermocoupleaswellasthebottom.Ittookthesystem12minutestoreach23degreesupstairs,afterwhichthetemperatureplateaued.Oncethisplateauwasreached,thesystemwasturnedontoseeifithadanyadverseeffect.Withthesystemturnedon,thetopfloortemperatureimmediatelybegantodecreasewhilethebottomfloorbegantoincreaseshowingacleartransferofenergyoccurring.Afterthistrial,thetopandbottomfloorswereonceagainsetto35degreesand10degreesrespectively,butthistimethefanwasrunimmediately.Withthefandrawingcoolairfromthebasementupstairs,thetemperaturereached23degreesinonly5minutes.Thiswasadramaticdifferenceincomparisontothehouseattemptingtoreachequilibriumonitsown.Oncethe23-degreetemperaturewasachieved,thefanwasturnedofftoseewhatwouldhappen.Theupstairstemperatureimmediatelybegantoincreasewhilethebasementbegantodecreaseduetothethermalmassesreleasing/absorbingenergy.
Thesetestswererunatthemaximumfanspeedof8cfmtodemonstrateproofofconcept.However,inthenexttrial,thefanwasrunatitsminimumspeedof2cfm.Atthisflowrate,thetemperatureredistributionoccurredjustasquicklyaswhenthefanwasrunat8cfm.Thisdemonstratesthatathighflowratevalues,coolingcapabilitybecomesindependentofflowrate.Ideallythesetestswouldberunatmuchlowerflowratestomorecloselyreplicatethevolumeofairredistributedinanactualhome,butflowratesthatlowarenotpossibletoachieve.Withaflowrateofapproximately400cfmfoundintheactualhome,andruninthesimulation,wewouldbeleftwithaflowrateof0.05cfmafterapplyingour1:20scaleonallthreedimensionsoftheprototype.
RAINWATERMANAGEMENT
SENSORCALIBRATION
Oneofthemostcrucialcomponentstowardshavingasystemthatworkseffectivelyandreliablyistheinstallationofthemoisturesensorunderthesoil.Afterperformingplentyofproductresearch,weconsideredcheapsensorsandexpensivesensors.Thedrawbacktohavingacheapsensorinstalledonourprototypewouldhavetodealwithlargeerrortolerancesanddatathatcontainedalargeamountofnoise.Withamoreexpensivesensor,thedatareceivedwouldbecleanandextremelyeasytouseandtune.Forthepurposeofourprototype,wedidnotneedmanyofthefeaturesthatarereceivedwith
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moreexpensivesensors,suchastemperatureandhumidityreadings.Afterconsideration,wesettledontheEC-5sensorfromdecagondevices(DecagonDevices,2015),whichismodestlypriced.Thisisananalog,volumetricwatercontent(VWC)sensorthatusesthedielectricconstantofthesensedmediausingcapacitanceandfrequencydomaintechnology.Itallowsfortheaccuratemeasurementofallsaturatedsoilsbetween40-60%water.
FIGURE18PICTUREOFTHEEC-5SENSOR(DECAGONDEVICES,2015)
VOLUMETRICWATERCONTENT
Thevolumetricwatercontentinamaterialistheamountofwaterwithinthehostmaterial.Inourcase,thehostmaterialispottingsoil.Itisdescribedmathematicallybelow(Wikipedia,2016).
!"# = !!!!"#
Where!!isthevolumeofwaterand!!"# isequaltothetotalvolumeofthewetmaterial.Thewetvolumecanbeexpandedas,!!"# = !! + !! + !!.Where!!isthevolumeofthehostmaterialand!!isthevolumeofair.
EQUATIONS
Forappropriatecalibrationofthesensor,youmustchooseanequationdependingontwoimportantinputvariables.First,thesoiltypeyouareusingandsecond,theinputexcitationvoltageofthesensordependingonyoursensorpoweringmethod.Inourapplication,weusepottingsoilforthepurposesofprototypetestinganddesignfairviewing.Thesecondinput,whichisexcitationvoltage,is3.3Vpowered
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directlyfromthebreadboardconnectedtotheWandboard.Thefollowingistheequationweusedforthecontrolsystem;weobtaineditdirectlyfromDecagonDevices(DecagonDevices,2015)forpottingsoilanda3.3Vexcitationvoltage:
!"# = 0.00992 ∗!!!"#!$% − 0.45
TheEC-5sensorislesssensitivetovariationintextureandelectricalconductivitythanothermoisturesensorsbecauseitrunsalowmeasurementtimeof10ms.Thisisbeneficialforeasyapplicationtomanymineralsoils,withthecalibrationequationsnotchangingsubstantiallyfromonesoiltoanother.Unfortunately,anappropriatecalibrationequationmustbeobtainedfortheexcitationvoltageused,sincethiscancausealotofvariation.Forinstance,thefollowingistheequationforpottingsoilatanexcitationvoltageof2.5V:
!"# = 0.00211 ∗!!!"#!$% − 0.675
Testswereruninordertodeterminethedifferencebetweentheseequations.Wewantedtoensurethatthedatareceivedandtransformedfromtheseequationswasclearlybetterandmorereliable.Thefollowinggraphdemonstratesthistest:
FIGURE19SENSORCALIBRATIONEQUATIONSCOMPARED
Asseenfromthefigure,thedatastreamsfromtheappropriate3.3Vexcitationvoltageequation(foundinpurpleandyellow)haveasmallerstandarddeviationof1.06onaverage.Thestandarddeviationfrom
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the2.5Vequationsyieldedanaveragestandarddeviationof1.39,whichis30%higherthantheappropriateequation.Withtheuseofanappropriateequation,thesesensorscanobtainanadvertised0.25%resolution.Onemustensurethattheappropriateequationisusedaccordingtotheexcitationvoltage,withalotofflexibilitylyingamongstthetypeofsoilused.
CONSTANTSANDTHRESHOLDS
Inordertoformulateacontrolsystemlogicthatisreliableandeffective,wemustbaseitfromconfidenceinwateringconstantsandthresholdvalues.Thesevaluesdescribeapointinwhichwedeemthesoiltobeadequatelywatered;thisisbasedontestingandresearchedvalues.Below,thereisafiguredescribinginputdatafromasensorwhileaplantiswatered.
FIGURE20SENSORTHRESHOLD-WATERINGSOIL
Note:Thedataforthisfigurewasrecordedwiththe2.5Vexcitationvoltageequation.
Inthefigureyouwillfindthethresholdvalue(horizontalline)withdatasectionsaboveitandbelowit.Thedatafoundfarabovethelineisthesensorindrysoil.Whenthebluelinedropsbelowthethresholdvalue,youcanseethatthedatabecomesscatteredforapproximately1secondbeforeitsettlesatavaluebelowthethreshold.Thesoilisnowconsideredadequatelywatered.
Withtheinclusionoftheappropriatecalibrationequationasstatedabove,thefinalthresholdvalueforthepottingsoilusedwas430.Onemightexpectthatasthesoiliswateredthevaluewouldincrease,butinreality,therelationshipisreversed.Asthesoiliswatered,thevaluesofincomingdatawilldrop.Thisrelationshipisstrictlyareflectionofthemethodonwhichthesesensorsfunction,andthatisthedielectricconstantofthemeasuredmediausingcapacitanceandfrequencydomaintechnology.
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NOISEFILTERING
Duringtesting,therewasnoisethathadtobedealtwith.Thegraphbelowdepictsthisnoiseanditsinherentproblemsduringimplementationinourcontrolsystem.
FIGURE21NOISEFOUNDINSENSOR2
Theorangelineshowsthattheincomingdatafluctuatesbetweentwomeanswhilethebluelinesitsconstantlyononemean.Thisfluctuationwasofgreatsurpriseintestingbecausebothsensorsareinthesamesoilcup.Aftermuchinvestigation,thefluctuationsweretiedtoanairpocketinthesoilbeingsituatedbesidethesensor.Methodsonhowtopreventthisfromhappeningaredescribedinthefollowingsection.
SENSORPLACEMENT&BESTPRACTICES
InordertoobtainconsistentdatafromtheEC-5sensor,timemustbetakentoensurethatitisinstalledcorrectly.Toretrievethebestdatapossible,itisbesttomaximizethecontactbetweenthesensorandthesoil(Devices,2015).Notonlyshouldtheprongsofthesensorbeburied,butalsotheblackovermoulding.Themostimportantaspectofinstallingthesensoristoensurethattherearenoairgapsinthesoilaroundthesensor.Topreventthis,wefoundthatiswasmosteffectivepressdownthesoilthoroughlyaroundthesensorafterthesensoriscompletelysubmergedinthesoil.Itisimportanttobeverygentlewiththeprongsonthesensortokeepthemintact,aswellasnottobendtheblackovermouldingtopreventanyinternalconnectionfailures.
SENSORERROR
Whenmoisturevalueswereretrievedfromtwosensorsinthesamemoisturecontent,therewasalwaysdiscrepancyamongmeanmoisturevalues.SinceDecagonguaranteescertainaccuracyinitssensors
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(DecagonDevices,2015),thediscrepancymustresidewithinthebuildofourprototype.Thedatareceivedfromthesensorsistransferredthroughsolderedconnections.Underthebudgetwewereunder,thesolderedconnectionsweredonein-house.Sincetherewasnowaytoguaranteecompleteuniformityintheseconnectionswiththeequipmentwehadavailable,thiserrormustresidewithinthispartoftheprototype.Thefigurebelowdemonstratesthedifferenceamongincomingdatameans.
FIGURE22DISCREPANCYAMONGSENSORMEANS
Note:Thedataforthisfigurewasrecordedwiththe2.5Vexcitationvoltageequation.Thesediscrepancieswerestillfoundwiththeproper3.3Vequation.
Withtheapplicationsofourprototype,thesediscrepancieswerenotdetrimentaltothelogicofourfinalcontrolsystem.Thediscrepancyusuallysataround5unitsofvolumetricwatercontent,whichtranslatestoapproximatelya1%difference.Decagonguaranteesanerrorof0.25%fromitssensors(DecagonDevices,2015),thereforeatleast0.75%ofthiserrorresideswithinourprototypesetup.
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FIGURE23LOCATIONOFSOLDEREDCONNECTIONS
DATAINTERPRETATIONS
Adifficulttaskofanyprojectistotakeindatafromapurchaseddeviceandtranslateitintoaformthatisusefultotheproduct.Inourcase,theEC-5sensorproduceddatathatwasinitiallynoisefilledwithvaluesthatseeminglyhadnorelationtounitsofvolumetricwatercontent.Asdiscussedinprevioussections,weappliedappropriatecalibrationequationsandderivedbestpracticesforoptimalsensorplacement.Thisresultedindatathatwasfarmorereliableandmeaningful.Thissectionaimstooutlinethetestsweusedtodevelopconfidenceinourdataaswellasoutlineimportantsensorcharacteristics.
TESTTYPES
InordertoensurethattheEC-5sensorswereworkingtotheirfullpotentialinourproduct,werandifferentteststomitigatetheeffectofhumanerrorsandprototypebuildinconsistencies.Theinitialtestweraninvolvedfillingupcupswithequalamountsofsoilandplacingtwosensorswithineachconsecutivecup.Thepurposeofdoingthiswastoensurethateachsensorwasrecordingasimilarmeanmoisturelevel.Thefollowingfigureshowsoneofthesetests,wherethesensorsareplacedinthecupat
Locationofsolderedconnections.
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thebeginning.
FIGURE24SENSORCALIBRATIONTEST-2SENSORSINONECUP
Thesecondtestweranwaswithbothsensorsinthesamecupagain.Duringthesecondtesttypeweaddedasmallamountofwaterinanattempttorecordatrendofincreasingdatavalues.Theresultsofoneofthesetestscanbeseeninthefollowingfigure.
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FIGURE25SENSORCALIBRATIONTEST–2SENSORSINONECUPWITHWATERADDED
Itshouldbenotedthatthedownwardtrendoftheresultingdatawasnotassignificantaswewouldhaveliked.SincethetestwasrunintheearlystagesofhavingtheEC-5sensor,wehadnotyetdevelopedbestpracticesfortheirinstallation.Oncethesebestpracticeswerediscovered,thetrendwasmuchmoredrasticandreflectedmuchmoreusabledata.Thedatawasfurthertunedwiththeimplementationofthecorrectcalibrationequation.
SYSTEMPARAMETERS
Aftertesting,importantsystemparameterswererealized.Inanyelectromechanicalsystem,thephysicalnatureoftheseparametersmustbedeterminedandaccommodatedinthedesignofthecontrolsystem.Inoursystem,theseparametersrelatetoeachotherthroughtheinputofsensorvalueandtheoutputofpumppowerandvalveorientation.Themostimportantaspecttokeepinmindisthesettlingtime,whichisthetimeistakesforasystemtosettleclosetoitssteadystatevalue.Withoutbeingawareofsettlingtime,oursystemwillcorrespondinglybeoverwateredwhichwillresultinwastage.Ifwateriswasted,itwilldefeatthefundamentalpurposeofthesystem!
Throughexperimentation,thesettlingtimewasdeterminedtobeapproximately30seconds.Thereasonitissolongisduetothesoil,andthetimeittakesforfreshlyappliedwatertosoakintoit.Oncethewaterhassoakedin,thatisthemoisturevalueweareinterestedinmonitoringwhilethecontrolsystemisrunning.Anotherimportantsystemparameterinoursystemistherisetime,whichisthetimeistakesforasystemtorisefrom10%to90%ofitssteadystatevalue.Inoursystemthisdirectlyappliestotherateatwhichwaterisappliedtothesoil.Thisrateistunedbywaterdivertingvalvesandpowertothepump.Thisisadifficultparametertotuneperfectlyduetotheinconsistencieswiththetimeittakes
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fordifferentsoildensitiestobecomesaturatedwithwater.Overthecourseofourtesting,wewerenotabletorunenoughteststoinstiladequateconfidencewithinourselvestosettleonanexactrisetime.Theparametersthatadjustrisetimecanbesolidifiedafterrunningmoretests.
PROTOTYPEDEMONSTRATIONS
Forpurposesofdemonstratingthesystematthedesignfair,weimplementedacontrollogicthatcommunicatedthefundamentaldecisionmakingpowerofthesysteminthesimplestwaypossible.Asseeninthefigurebelow,theprototypewassetupwithtwosoilcupseachhavingonesensorplacedwithinthemandanirrigationlineplacedabovethem.Thevalvescontrolledtheirrigationlinesindependently.
FIGURE26PROTOTYPEATDESIGNFAIR
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Differentdemonstrationswererunatthedesignfairtocommunicatethatthesystemwasintelligentenoughtodecidewhich‘zone’orcupneededwatering,andforhowlong.Themostcommondemonstrationwastheplacementoftwosoilcupswithslightlydifferentmoisturelevels.Duringthedemonstration,bothcupswouldinitiallybecomewateredbythepumpbuttheywouldbothpassthethresholdmoisturevaluesatadifferenttime.Thiscommunicatedhoweach‘zone’isindependentofoneanother.
Otherrunsweresetuptodemonstratethatthesystemcouldimmediatelyrecognizeaproperlywateredzone.Thiswasdonebyplacingasensorinapreviouslywateredcup,whichresultedinthesystemhavingknowledgeofthewateredstatusandsimplymonitoringituntilthesoildriedup.Overall,thedesignfairdemonstrationsworkedeffectivelyandcommunicatedthedesignconceptwell.
PROTOTYPEROADBLOCKS
Aswithanydesignproject,thereareinevitableproblemsanddesignchallengesthatyoumustovercome.Withinourproject,thereweresomethatwerehardertosolvethanothers.Fortunately,wewereabletosolvealltheproblemswefaced,allowingustodeliverallaspectsoftheinitialscopeoftheproject.Belowthereisanoutlineoftheproblemsweencountered.
VALVEOPENINGANDCLOSING
WiththedecisiontomoveforwardwiththeWandboardmicrocontroller,welimitedourselvestocertainpowerlevels.Thesepowerlevelswereneededtoactuatethevalvesthatcontrolflowtodifferentzonesinoursystem.Inordertogreatlysimplifythesystem,welookedforvalvesthatcouldbeactuatedbya5vsourcebuiltdirectlyontotheboard.Thisremovedtheneedforexternalpowersourcesandmoreelectricalswitchesaddedtothephysicalcontrolcircuit.
TheonlyvalveswewereabletofindwereonesavailablethroughAliExpress(AliExpress,2016).Thesevalvesseemedverypromisinguntiltheyarrived.Wequicklydiscoveredthattheyrequiredapositivevoltagepulsetoopen,andanegativevoltagepulsetoclose.Thisisquitedifferentfromourexpectationofhavingtosimplyapplyconstantpowertoopenthevalve.Thisproblemwasoneofthelargestinourproject,andwaseventuallysolvedusingacombinationofelectricalswitches(transistors)aswellasmechanicalrelaysthathadtwoinputsaswellasoutputs.Asmentioned,theproblemwassolvedusingtheresourceswehadaccesstoo,butinfuturerevisionsofthisproduct,avalveshouldbechosenwithmorestandardizedcontrollogic.
CODINGLANGUAGEDISCREPANCIES
Sincethisproduct’sprimarysellingfeatureisitsabilitytorunautonomously,weneededtocodethecontrolsysteminalanguagethatisnotveryCPUintensive.ThisimmediatelyclosedoutthepossibilityofitbeingcodedingraphicalcodinglanguagessuchasLabvieworMatlab’sSimulink.Inlightofthis,ourteamdecidedtocodeinPython,becauseofitslargefunctionlibrary,simplemathematicaloperationsandbecauseofitsquicklearningcurve.
SincetheoperatingsystemweloadedontotheWandboardisUNIXbased,theeasiestwaytoaccessincomingdatafromoursystemwaswithsimpleBashcommands.Unfortunately,Python’sabilitytoreadandwritedatathroughtheuseofBashcommandsisanythingbutsimpleforagroupofmechanicalengineers.Throughtheuseofbackgroundresearch,wewereabletomakethecodereadandwriteto
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oursystemusingPython’sOpen/Write/Closecommands.ThisroadblockmadeourgroupquestionthedecisiontocodeinPythonmanytimes,butitwaseventuallysolvedwiththeuseofthecorrectPythonfunctions.
PUMPFAILURE
Asdiscussedinanearliersection,thedesignfairdemonstrationswereperformedinawaytoshowasmanypeopleaspossibleoursystemworking.Withthisconstantresettingofthecontrolsystem,thepumpwasforcedtopowercyclerepeatedlyforhoursatatime.Withthispowercycling,thepump’sinternaloverheatswitchwastriggeredandthepumpfailedtoproducesufficientpressureforoursystemcorrectly.Fortunately,thisfailureoccurredwithahalfanhourleftinthefair.
Thisfailurewasnotedandanalyzedasapotentiallong-termissueforoursystem.Weconcludedthatitwouldnotbeaproblemforthissystemifitweredeployedtothefield.Thereasonbeingisthatthepumpwouldneverhavetopowercyclerepeatedlyinthesettingofagarden.Itwouldbepoweredononceortwiceadaytoprovidethesufficientamountofwaterfortherequiredzones.Oncethezoneshavebeensufficientlywatered,thepumpwouldlayinanidlestatewaitingforthesoiltodryoutonceagain.Asmentioned,thisfailurewasnotoverlyconcerninginthecontextofactualproductfunctionality.Inordertoensurethehighestlevelofconfidence,wewouldimplementapumpthatwehavetestedextensivelyandweknowcanhandlealloperatingmodesofthesystem.
PRESSUREISSUES
Thepumpusedinoursystemworkedverywellfortheapplicationofthisprototype(asidefromtheproblemmentionedabove).Theonlydrawbackwithitsapplicationtoourcontrolsystemwasitslackofpowervariability.Whenthepumpisconnectedtoa110VACwalloutletitwouldsimplyturnonandprovideitsspecifiedoperatingpressure.Inthecontextofthedripirrigationtubingusedinourprototype,andpotentiallywiththeproduct’sfieldimplementation,thispressureissimplytoomuch.Itprovidesfartoomuchwaterintoshortofatime.
Thesolutiontothisproblemtookplaceintwostages.Thefirststagewaswiththeacquisitionofapressurereducerthatprovidedaconstantoutputpressureequaltothestandardoperatingpressurefordripirrigation(25PSI,(Smeal),(TheHomeDepot,2016)).Withthisaddition,thewaterreceivedattheoutletofthedripirrigationlineswasmuchsmallerandfareasiertoworkwithduringthecodingofourcontrolsystem.Adrawbacktothisadditionwasthatthebackpressurenowplacedonthepumpwasmorethantheratedamountforthegasketsealingtheplatearoundthepumpsimpeller,whicheventuallycausedacatastrophicleak.Afterthegasketwasreinstalled,awaterdiverterwasaddedtotheoutletofthepump,whichallowedthemajorityofthewatertoberecycledtothewaterholdingbin.Thewaterdiverterhadbuiltinvalves,whichallowedforeasytuningofvolumetricflowratesineachdirection(TheHomeDepot,2016)(i.e.eithertothedripirrigationlinesorbacktotheholdingtank).Withtheadditionofboththepressurereducerandthewaterdiverter,wewereabletoobtainthecorrectoperatingpressureforthesystemwhilealsopreventingpumpleaks.
COMMERCIALIZATIONOFTHEPRODUCT
Movingforward,thisproductwouldbemarketedtowardsindividualslookingforanautonomouswaytoensureahealthylawnwhilealsosavingwater.Inordertogettheproducttothiscommercializedlevel,wemustelicitthehelpofelectricalengineerswhocanredesignthephysicalnatureofthecontrol
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systemontoaprintedcircuitboardaswellaswriterobustfirmwarelogicforembeddedoperationsinthemicrocontroller.Aftertheprintedcircuitboardisconstructed,theuserwouldsimplyconnecttherequiredamountofsensorsfortheirapplicationandinterfacewithapumpandvalves.
Inordertomakethisproductuserinstallable,aswellasuserconfigurable,wewouldworktoeitherintegrateamobileapplicationorwebsitethateasilyconnectsthemtoimportantsystemparameters.Thebenefittomakingthesystemsoconfigurableisthatisallowstheusertoeasilychangezonerequirementsandwateringguidelines.Withabuiltindatabaseofwateringrequirementsformanycommonplants,thesystemwouldhaveexistingknowledgeofall-importantparameters.Thismakessetuptimeverysmallwhilealsoensuringstressfreesystemchangesinthefuture.
SCENARIOMODELING
InordertoderiveanestimateofthepotentialGHGemissionssavingsaffordedbythereasonably-expecteddeploymentofthein-linefanandrainwatermanagementsystems,wemodelledtheenvironmentalimpactsexpectedundertwoseparatescenarios:1)thebusiness-as-usual(BAU)scenariobasedontheemissionsofastandardAlbertahome,and2)thealternativescenariobasedonanAlbertahomesupplementedwiththein-linefansystemortherainwatermanagementsystem.Thegrowthofsingle-detachedhomesinAlbertawasestimatedusingtheCanESSmodelforaenergy-basedeconomyassumingalow-oil-sandsgrowthscenario.Ofthesehomes,thenumberofexpectedsingledetachedhomeseachyearbetween10and30yearsoldwasestimated.Weassumedourproductcouldbedeployedtoamaximumof5%ofnewlyavailablesingle-detachedhomesoftherequiredagerangeeachyearwithintenyearsofstartingupaprospectivebusinesstosellthesystem.
ThegrowthinthenumberofresidenceinAlbertafortheBAUscenario(Figure20a–bluearea)isexpectedgrowbutdeclineintherateofgrowthduetothedeclineinoilsandseconomicactivitypredictedbythelowoilsandsgrowth.ThisscenarioassumesanddemonstratesthatoilsandseconomicactivityisasignificantdriverofimmigrationandresidencegrowththroughoutAlberta.ThegreenhousegasemissionsestimatedforallAlbertaresidencesunderthisscenario(Figure20b–reddashedline)isthesumoftheemissionsfromconsumingnaturalgasinhighefficiencyfurnaces,andthosederivedfromtheAlbertaelectricalgridbasedondemandforelectricitypredictedfortypicalACunits(200BTUspersquaremeter,and0.15W/BTUpowerrequiredforheatclearance)standardizedtotheaverageexpectedhomeareaeachyear.ThewaterusageestimatedforallAlbertaresidences(Figure20c–reddashedline)istheexpectedaverageAlbertaresidentialoutdoorwaterusagemultipliedbythetotalnumberofresidenceswithlawns,whichwouldexperiencesuchdemand.
Inordertoconstructthealternativemodelanumberofcriticalassumptionsconcerningthedeploymentandintegrationofthein-linefanandwatermanagementsystemswererequired.First,thepotentialutilizationofthein-linefansystemwasestimatedbasedontheresultsfromtheSimulinkmodels.Althoughthemodelspredictedapotential1/3utilizationfactorforthein-linefan,aconservativeestimateof1/4wasusedtoaccountfornon-idealclimateconditions.TheACadoptionratewasconsideredstaticforAlbertathrough2060andwassetat27%(REFERENCE?).Theadoptionofnaturalgas-basedheatinginhomesinAlbertawasalsoassumedtobestaticanduniversalforallhometypes,andwassetthrough2060to90%.Theaverageefficiencyofthesefurnaceswasestimatedat90%(asmustareeitherhighormediumefficiencyat95%and85%,respectively.Theutilizationoftherainwatermanagementsystemwasestimatedat90%ascapacity-basedcalculationsdemonstratedthatasuitably
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constructedrainwatercollectionsystemhadthepotentialtooffsetnearlyallofthehome'swaterdemand.
Giventheseassumptions,weestimatedthatwithin20yearsofdeployment(by2037),thein-linefansystemcouldcutemissionsfromAlbertahomesby16MtCO2eperyear(foracumulativetotalof157MtCO2e),andtherainwatermanagementsystemcouldlowerAlbertawaterusageby11millionm3peryear(foracumulativetotalof26millionm3).Thein-linefansystemisparticularlyusefulforavoidingAC-derivedemissionsduringthesummermonths,asourSimulinkmodelsuggestedthatarelativelycoolbasementfloorhasthepotentialtosufficientlycoolahomeandalmostcompletelydisplaceACusage.Thisisparticularbeneficialasairconditioningreliesonrelativelycarbon-intenseelectricityfromtheAlbertagrid.TheAlbertagridreliesoncoal-basedpowerfornearlyhalfofalldemandgenerationwhichemits1020kgCO2e/kWh,whereasnaturalgasemitsapproximately400kgCO2e/kWh.However,ascanbeseeninFigure20b,thecarbonfootprintofthegridisexpectedtodeclinerapidlythroughto2050duetothegradualretirementofcoal-firedpowerplantsinAlbertaandtheirreplacementwithacombinationofnaturalgas-basedpowerandalternativepowergenerationsourcessuchaswindandsolarphotovoltaic.
TherainwatermanagementsystemhasthepotentialtobeaveryeffectivetoolinmitigatingwaterusageinAlberta.Someestimatessuggestthatsimplyapplyingawatermetertoahomecanreducetheburdenonwatertreatmentfacilitiesbyreducinghomewaterconsumptionbyupto50%.Thiscurrentsystemisabletocompletelydisplaceahome'sdemandfortreatedwaterforoutdoorwateruse,offeringtofurthersuppresstotaldemand.ThemainbarriertoincreasingthetotalresidentialwaterusageseeninFigure20cistheadoptionofthesystembyconsumers.
Figure25illustratestheprojecteddeploymenttosingle-detachedhomesinAlbertabeginningin2016andprojectedto2060.b)Within20years,thepassiveheatingandcoolingsystemcouldcutemissionsby16MtCO2-eqannually(157MtCO2-eqcumulative),whilec)therainwatermanagementsystemcouldlowerAlbertawaterusageby11millionm3annually(26millionm3cumulative).
FIGURE27PROJECTEDDEPLOYMENTOFSYSTEMS
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RECOMMENDATIONS
IN-LINEFAN
Recommendationsforthefuturedevelopmentoftheinlinefansystemarebasedonthecurrentresultsandbestunderstandingofthesystemandwillbebrokendowninto3majorcategories:
1) Recommendationsforadditionalphysicalandcomputermodeltesting2) Marketanalysisanddeploymentstrategies3) Nearterm(10year)potentialandscheduleforcontinuedproductdevelopment.
TESTINGRECOMMENDATIONS
Forfurtherengineeringdesignanalysisandtesting,werecommend:1)completephysicaltestingoftheprototypeinconditionssimilartotheextremeseason(winterandsummer),2)testingthecapacitytocontroltheremainingfloorsofthemodelhome,3)developingamethodtooptimizethecontrolsystemforavarietyofdifferenthomeconfigurations,and4)developingavarietyofrepresentativehometypesforsimulationinSimulink.
First,completingasecondstageofphysicaltestingofthemodeltobettercharacterizeitsperformanceindifferentphysically-simulatedenvironmentalconditionscouldhelptobetterunderstandtheparticularadvantagesthesystemoffersindifferentseasons.While‘summercondition’testingindicatedthattheairconditioningsystemsthatarestandardinroughly27%ofhomescouldbealmostentirelyoffset,itwouldbeinterestingtoknowhowthesystemperformsinwinterconditions.Theseresultscouldhelpinformadeploymentstrategy.Forinstance,iftheairconditioningfunctionappealstomanyhomeowners,thiscouldencourageearlyadoptionandcouldbestrategicallypursuedinordertogaininsightintothefunctionofthesysteminmanyhomes.Next,testingofthemodelonthemainandbasementfloorsareclearlyessentialinordertoensurethattheproof-of-conceptresultsaregeneralizableacrosstheentirestandardhome.
AgeneralizedmethodforoptimizingthecontrolsystemsettingsinordertoreducetheHVACenergyusageofabroadvarietyofAlbertahomeswouldbeanessentialsteptodecreasingengineeringcostsinfuture.Ashasbeenstatedpreviously,theengineeringcostsforsuchaprojectareexpectedtoberelativelyhighduetothecustomizednatureoftheretrofit.Reducingthiscostmayhelptomitigateaprimarybarriertoentryforconsumers.Thiswouldalsopermitourgrouptounderstandthepotentialofthistechnologywhendeployedtoabroadervarietyofhomes.Finally,thesedatacouldhelpustodevelopadditional‘non-standard’thermalmodelsofhomestodeterminetheirsuitabilityforsystemdeployment.
MARKETANDDEPLOYMENTRECOMMENDATIONS
Inordertobetterappealtoabroaderconsumerbaseandtounderstandthepotentialimpactofthesystemonenvironmentalimpacts,werecommend:1)conductingbriefsurveystoassesspotentialconsumers’willingnesstopayforasystemsuchasthein-linefanbasedonperception,cost,environmentalbenefitsandpotentialgovernmentsubsidies,2)marketingthesystemasatoolforimprovedairconditioning,and3)establishingasupplychainforthecriticalcomponents.
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Consumersurveyswouldbeessentialinallowingustostrategicallymarketoursystemtotheconsumersmostlikelytobewillingtopurchase.Itwouldalsogiveinsightintowhatconsumersfeelismostattractiveaboutoursystem(environmentalwell-being,costsavings,etc.)whichwillhelpustodirectourtechnicaltestingeffortstowardssolutionswhichwouldofferthegreatestappealtothesemarkets.Forinstance,testingindicatesthatthissystemmayuniquelybeabletooffsetaverylargeproportionofhomecoolingneeds.Ifthisprovedtobeanattractivefeaturetoconsumers,wecouldstrategicallypursuegainsincoolingpowerandperformancefirstinordergainagreatermarketshareearlier.Finally,thepursuitofagreatermarketsharerequiresthatasupplychainfortherequiredpartsformthemicrocontrollerstothestandardductingandwiringbeestablished.Thefundamentalabilitytodeploythesystemondemandtowaitingconsumersiscriticaltotheearlysuccessofthissystem.Theearlierthesuccessisinproductdeployment,thegreaterthereductionsinenvironmentalimpacts,whichbenefitseveryone.
NEARTERMSCHEDULERECOMMENDATIONS
Apredictionofthescheduleforpotentialneartermdeploymentisusefulforpredictingincomeandtoencouragethetimelycompletionofengineeringtasks.Assuch,werecommend:1)establishingafinalfullscaleprototypewhichcanbedeployedtoanumberofhomestocollectrelevantperformancedatawithinthefirstyear,2)basedonmarketdata,seekoutthebroadestpossibleconsumerbaseofpeoplewillingtodeploythesystemintheirhomeswithinthefirst5years,and3)attempttomarkettheearlysuccessesandbenefitsofoursystemtoabroaderconsumerbasewithinthefirst10years.
RAINWATERMANAGEMENT
Basedontheresultsobtainedfromourprototypeandtheresearchputintoourproject,thefollowingrecommendationsweredevisedinordertoprogressthisproject’sfuturedevelopmentintoaneventuallymarketableproduct.
TESTINGRECOMMENDATIONS
Inordertoimproveontheprototypescurrentsuccessfurthertestingwillberequiredsothatahigherlevelofeffectivenesscanbeobtained.Suchtestingincludes1)furthertestingofthesensorsaccuracywithreadingvolumetricwatercontent,2)testingthesystemsperformancewithdifferentsoilconditions,3)testsystemsabilitytointerpretdatafromseveralsensorsinfieldapplications.
Currentlyoursystemisabletoadequatelycontrolthedistributionofwaterbetweentwozonesofthesamesoiltype,arelativelysimpleapplication.Moreintensivetestswiththedataobtainedfromthesensorscouldpotentiallyimprovetheaccuracyofthesystembytweakingtheequationsusedforinterpretingthedata.Also,testingthesensorsindifferentsoilconditionswouldestablishtheparametersnecessaryforproperlycalibratingthesensorsindifferentsoiltypes.Accountingforadelayinthetimeittakesforthewatertoreachthesensordependingonthesoilsporosityisanadditionalrequiredexperiment.Thesetestswouldensurethatonlythecorrectamountofrequiredwaterwouldbedistributedtoeachzoneandwouldallowthesystemtobeeasilyretrofittedintoanyyard.Sinceourprototypeonlyneededtointerpretdatafromtwosensorstheamountofdataitcollectedwasrelativelylow.Infieldapplicationsthenumberofsensorsrelayingdatawillbemuchlarger,thereforethecontrolsystemwillhavetobefastenoughtoefficientlyprocesstheselargeamountsofdata.
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MARKETANDDEPLOYMENTRECOMMENDATIONS
Inordertomakeourproductappealingtoconsumersthereareafewareasthatneedtobeimproveduponbeforemakingitamarketableproduct:1)inquiretheskillsofanelectrical/softwareengineertodevelopauserinterfaceand2)createaproductwithsimplepartsforeasyintegration.
Thepotentialforthisprojectishugeintermsofuserinteractionwiththesystem.Ifweweretogetanelectrical/softwareengineerinvolvedwithdevelopingasimpleuserinterfacethenourproductappealgreatlyincreases.Theuserinputwouldsimplyneedtoprompttheuserforpertinentinformationregardingtheyardthatitisbeingimplementedinto.Also,futuredevelopmentswouldincludecreatinganappthatcouldbeinstalledontheuser’smobiledevice.ThenbyusingtheWi-FicapabilitiesoftheWandboard,theuserwouldbeabletointeractwiththecontrolsystemtherebybeingmoreinvolvedwiththesystemsoperations.Alongwithdevelopinganapp,simplifyingtheproductionofthecontrolsystemandthesensorswouldreduceconsumercostsandpotentiallyincreasingitsdemandandeaseofuse.
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CONCLUSION
Wesetoutwiththeintentiontodevelopsystemsthatreducetheenvironmentalimpactsofmodernhomeswithsimpleandaccessiblemechanicalengineeringsolutions.Thephilosophybehindthisgoalisthat,inadditiontotheappealofenvironmentallysustainabletechnologiestoconsumers,thesystemsthatcouldofferthegreatestpotentialforenvironmentalimpactreductionarethosethatarecost-effective,andthereforemechanicallysimple.Wesetouttodeterminethepotentialoftwosystemsaffectingtwocandidateproblems:1)anin-linefansystemworkinginparallelwithastandardHVACsystemtoreducetheenergyrequirementsandthereforeGHGemissionsofmodernhomesand2)arainwatercollectionandautomateddistributionsystemwhichcoulddecreasethedemandofmodernhomesfortreatedwater.Weconstructedphysicalprototypes,aswellascomputermodelsandsimulationsinordertodeterminethefeasibilityofthesesystems,andtheirpotentialimpact.OurresultsdemonstratethatsimplemechanicalsystemscantakeadvantageofindoorandoutdoorenvironmentalconditionstoofferdirectbenefitstoAlbertahomeowners,aswellastotheglobalmarket.
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Wikipedia.(2016,March21).Watercontent.FromWikipedia:https://en.wikipedia.org/wiki/Water_content
APPENDICES
APPENDIXA–RAINWATERMANAGEMENTEXPENSEREPORT
Itemname Quantity Description PlaceofPurchase
Purchaser Price
24BITADC 5Analogtodigitalconverter-necessarytointegratesensorsintosystem
DigikeyElectronics
DanCojocariu $16.80
Solderlessbreadboard
1Breadboardisusedtointegrateallinputsandoutputstothemicrocontroller
DigikeyElectronics
DanCojocariu $6.88
Jumperwirebundle
1Wiresusedtoconnectinputs/outputsfromthebreadboardtothemicrocontroller
DigikeyElectronics
DanCojocariu $7.91
Shippingcost - - - - $8.00
Tax - - - - $1.58
TOTAL $41.17
WBDUAL-Wandboard
1Microcontrollerusedtoprogramcontrolsystem.Thisisthebrainsoftheoperationthatcontrolstheentiresystem
MouserElectronics
DanCojocariu $149.35
TOTAL $149.35
66
SoilmoistureEC-5sensors
3Soilmoisturesensorsusedtocollectdataforsystemtodeterminewhenplantsneedwatering
HoskinScientificLimited
DanCojocariu $390.00
Tax - - - - $20.66
UPSFreightCharge
- - - - $23.24
TOTAL $433.90
3.5mmStereoexternalcable
M/F4
Thesecablesareusedtoconnectandintegratethesensorsintothesystemduetotheconnectionrequirementsofthesensors
MemoryExpress DanCojocariu $27.96
FullyratedUSBcableA-a
1Thiscableisusedtoconnectthewandboard(microcontroller)tothecomputertoprogram
MemoryExpress DanCojocariu $6.99
16GBmicroSDcard
1Usedforthemappingofthewandboard.Theinterface/programiswrittenontotheSDcardandpluggedintothewandboard
MemoryExpress DanCojocariu $9.99
USBtotypeN5V 1Thiscableisusedtoconnectthewandboardtopowersothatitturnsonandoperates
MemoryExpress DanCojocariu $7.99
Tax - - - - $2.65
TOTAL $55.58
SolenoidValve 3
Thesevalvesareusedtocontroltheflowofwatertotheindividualzones
AliExpress DanCojocariu $50.37
Customs/Duties - - - - $17.48
TOTAL $67.85
67
RelaySSR3A 1 Thisrelayisusedtooperatethepump,turningitonandoffDigikey
ElectronicsDanCojocariu $30.77
TOTAL $30.77
TransistorNPN,400V,3A
6Thetransistorsareusedinthecircuittoaidtheoperationofthevalves
DigikeyElectronics
DanCojocariu $5.58
Transistor,NPN,80V,15A
6Thetransistorsareusedinthecircuittoaidtheoperationofthevalves
DigikeyElectronics
DanCojocariu $7.74
Tax - - - - $0.67
Shippingcost - - - - $8.00
TOTAL $21.99
Variousirrigationsupplies
-Thisbundleofitemswasboughttobuildtheprototype.Therearemanylittleparts,listingeachwouldbetediousandunneccesary
HomeDepot DanCojocariu $116.41
Variousirrigationsupplies
-Thisbundleofitemswasboughttobuildtheprototype.Therearemanylittleparts,listingeachwouldbetediousandunneccesary
HomeDepot DanCojocariu $26.82
LawnSoil 1 Boughtadditionallawnsoilusedforthetestingoftheprototype HomeDepot DanCojocariu $6.28
BrasshoseYconnector
1Usedtooptimizethepressureonthepump,andintroduceawaterrecycleintothesystem(prototypeoptimization)
HomeDepot DanCojocariu $13.10
Variousirrigationsupplies
-Additionalirrigationsuppliestooptimizetheprototype.Aftertestingwasdoneandissuesidentified,thiswasdeemednecessary
HomeDepot DanCojocariu $36.81
68
Variousirrigationsupplies
-Additionalirrigationsuppliestooptimizetheprototype.Aftertestingwasdoneandissuesidentified,thiswasdeemednecessary
HomeDepot DanCojocariu $17.72
GasketSealer 1 Usedtosealthepumpandensurenoleakage CanadianTire DanCojocariu $7.34
TOTAL $224.48
RUNNINGTOTAL
$1,025.09