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UseAirCirculationFantoReduce
TemperatureDistributioninElectric
Smokers
Part1:ThetemperaturedistributionwithcirculationfaninaBradleySmoker
Version1.0(August,2019)
Abstract
Anaircirculationfankit(CIRFAN)wasinstalledina4‐rackBradleyOriginalSmoker,and18probeswere
installedinthesmokertomonitorthe3‐Dtemperatureprofileinthesmoker.Theeffectofthe
circulationfanonthetemperaturedistributionwasstudiedunderdifferentconditionsbyvaryingtheset
temperature,addingornotaddingobjectstoblocktheairflow,turningonoroffthesmokergenerator,
andopeningorclosingthetopvent.Theaveragetemperatureofallprobesandthestandarddeviation
werecalculated.ThetemperatureprofilewithandwithoutAuber’scirculationfanarecompared.The
circulationfansignificantlyimprovedtheuniformityoftheheatdistributioninthesmokerunderall
conditions.
Introduction
ThisisthePart1ofaseriestemperatureprofilestudiesthatwehaveperformedinaBradleyelectric
smoker.ThepurposeofthesestudiesistofindouttheeffectivenessofAuber’sAirCirculationFankitin
reducingthetemperaturedistributioninelectricsmokers.
Mostofhome‐useelectricsmokersdependonnaturalconvection(i.e.,gravityconvection)todistribute
heatinsideasmoker.Acommonissuewiththesesmokersisthatheatisnotevenlydistributedinsidea
smokerandtheproblemgetsworsewhenfoodisloadedinthesmoker.Foodloadedinasmokernot
onlyblocktheradiantheatfromtheheaterbutalsorestricttheairflowinsideasmoker.Whenfoodis
cookedatarelativelowtemperature,forexample,smokingsalmonat150°F,thetemperatureofthe
toprackcanbemorethan20°Flowerthanthatofthebottomrack.A20°Fdifferencecouldbeabig
problembecausethecookingtimeneededforcookingat140°Fismuchlongerthanthetimeneededat
160°F.Todealwiththisissue,peopleeitherhavetore‐arrangethesalmonpiecesinthemiddleofthe
cooking,orhavetotakeoutsalmonpiecesfromdifferentshelfatdifferenttime.
Introducingforcedairconvectioninsidethesmokercanhelpreducethetemperaturedistribution.
However,forcedairconvectionisnotreadilyavailableonsmokersforhome‐useyet.Manyenthusiastic
ownersofelectricsmokershadtriedtoaddcirculationfanstotheirsmokers.Buteffectivenessofthis
kindofmodificationshavenotbeencarefullystudied.Afterweexploredandtestednearlyallthe
availableoptions,wedevelopedourAirCirculationFanKit(partnumber:CIRFAN)toaddressthisissue.
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Inthisstudy,weperformedaseriesteststodemonstratehowmuchimprovementcanbeachievedby
addingourcirculationfantoatraditionalgravity‐convectionsmoker.
EquipmentandMethod
Equipment
A4‐racksBradleyOriginalSmokerwasusedinthisstudy.Asthesmokerhadbeenusedbefore,allwalls
insidewereindarkbrowncolor,whichrepresentedthetypicalheatreflectionconditioninhome
smokers.
AllprobesusedinthisstudyhadPlatinum(PT1000,ClassA)sensingelements.Probeswerecalibrated
withthecontroller/thermometerstogetheronaFluke9100dry‐wellcalibrator.Thereadingaccuracy
waswithin+/‐1°Faccuracyinthetestingtemperaturerange.
Totally18probeswereusedinthisstudy.Onthesecondrack(rack#2)fromthebottom,afree‐hanging
probe(partnumber: WS‐SENSOR17)wasclippedtothecenterbyaprobe‐clip(partnumber:Pclip).It
wasusedforcontrollingthetemperatureofthesmokercabin.
Onrack#1,#2,and#4,fiveprobesweremountedoneachrack:oneprobewasclippedatthecenter
andfourprobesatthecorners.Thepictureandthe3‐DimageinFigure1showprobes’locations.The
probesmountedatcornerswereAuber’sminiatureprobes(partnumber: WS‐SENSOR22),whichwere2
mmindiameterand20mmlong.Theyweremountedverticallyattheintersectionofthesecondwires
fromtheirnearesttwosides,i.e.,theywere2.75”(70mm)fromthesidewalland2”(50mm)fromthe
frontwallorthebackwall.Thisistoensureprobesinstalledatthecornerswereverticallyaligned.At
thecenterofeachrack,Auber’sfree‐hangingprobe(partnumber:WS‐SENSOR17)weremounted
horizontallybyaprobe‐clip(partnumber:Pclip).
Onrack#3,onlyafree‐hangingprobe(partnumber:WS‐SENSOR17)wereclippedatitscenterbya
probe‐clip.Noprobesweremountedatthecorners.
Eachprobeisnamedbyitsracknumberanditsrelativelocationinthesmoker.Forexample,“1_Center”
istheprobeonthecenterofthe#1rack,and“2_Back_Left”istheprobeattheback‐leftcornerofthe
#2rack.Theleftsideortherightsideofthesmokerisdefinedasthesamewaywearefacingthe
smokerandlookingintoit.
Inthespacebetweenrack#3andrack#4,twowall‐mountprobeswereinstalled.Awall‐mountprobe
(partnumber:WS‐SENSOR11)wasinstalledonthecenterlineoftheback‐wallofthesmoker,just
underneaththerack#4(i.e.,thetoprackfromthetop).Anotherwall‐mountprobewasmountedonthe
righthalfofthebackwall,justunderneaththerack#4,andabout4”fromtheside‐wallontheright.The
temperaturereadingsfromthesetwoprobeswerealsomonitoredandrecordedtoseeiftheirreadings
wereclosetothereadingsfromtheprobesonthecenter.Thesetwoprobeswerenamedas
“3_Wall_Center”and“3_Wall_Right”.
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(a) (b)
Figure1.(a),totally18temperatureprobeswereinstalledona4‐rackBradleyOriginalSmoker.(b),the
locationsofinstalledprobesaremarkedina3‐Ddrawing,whereeachprobeisrepresentedbyayellow
rodandtheredtipindicateswheretheprobetipis.
AnAuberWSD‐1500Hcontrollerwasusedwiththecenterprobeonthesecondrack(i.e.,probe
2_Center)tocontrolthesmokercabintemperature.TherestoftheprobeswerereadeitherbyAuber’s
WSD‐1500HorbySYL‐2615,bothofwhichwerePIDcontrollerswithWi‐Ficapability.Thesecontrollers
wereusedasthermometerstorecordedtemperaturereadingsfromtheseprobes.Alltemperature
readingsweretakenatleast30minutesafterboththereadingofthecontrolprobeandthepower
outputofthecontrollerwerestabilizedatthesetpoint.
Method
Thetemperatureprofileinasmokerovenwithorwithoutthecirculationfanwastestedundervaries
conditions:1)atsetpointof150°Forat225°F;2)withthesmoke‐generatorturnedonorturnedoff;3)
withthetopventingholecompletelyopenorcompletelyclosed,4)inanemptysmokerorinasmoker
withblocksofcardboardsheetsorcardboardboxestoblocktheairflow.
Thetemperatureprofileinanemptysmokercangiveusageneralideaofthewhetheracirculationfan
wouldhelpreducethetemperaturevarianceinasmoker,butitdoesn’tnecessarilyrepresentthe
situationunderarealcookingprocess.Thecardboardsheetsandcardboardboxeswereusedto
simulatefoodchunksintwodifferentrealcookingsituations:A)weused28piecescardboardsheets
thatwerecuttothesamesize(6”x1.5”)tosimulatethesalmonstrips.7piecesofcardboardwere
placedineachrack.Theyareevenlydistributedontherackwithgapsofsimilarwidthinbetween.In
ordertoavoidleavingabiggaparoundthecornersensor,ahalfinchholeispunchedtothecardboard
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thatwasplacedatthecorner.B)Inanothersimulation,weusedafewcardboardboxes(randomly
selectedandarrangedoneachshelf)tosimulatefoodchucksofdifferentsize.

(a) (b)
Figure2.(a),28piecesofcardboardsheetwerearrangedevenlyinallracksinthesmoker.(b),cardboard
boxesandcardboardsheetofdifferentsizethatwereselectedandrandomlyplacedinthesmokerto
simulatedifferentfoodchunks.
Results
Temperatureprofilesinthesmokerinvariesconditionsweretestedextensivelyandthetestswere
groupedintofoursections.Dataaresummarizedinatableineachsection.Ineachtable,thetesting
conditionsaregiveninthefirstafewrows,temperaturereadingsarelistedinthemiddle,andthe
statisticsofthedataaregiveninthebottomrows.Theprobe“2_Center”isdenotedbyanasterisksign,
indicatingitisthetemperaturecontrolprobe.
Undereachtestingcondition,wedidonetestwiththecirculationfanturnedoffandonetestwiththe
circulationfanturnedon.Datafromthesetwotestsarelistedside‐by‐sideinforeasiercomparison.
Thedatafromeachtestislistedinacolumn.Ineachcolumn,thehighestreadingismarkedinredcolor,
andthelowestreadingismarkinbluecolor.Thedataaverage,standarddeviation,andtherangeofthe
data(i.e.,thespanbetweentheminimumreadingandthemaximumreading)arecalculatedandlisted
atthebottomofeachtable.Theaverage,standarddeviation,andrangeofthecenterprobesarealso
calculated.
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1)EmptySmoker
Inthisgroupoftests,nocardboardsheetsorboxeswereusedtosimulatefoodchucksinasmoker.The
topventiscloseddowntoleave¼”gapsoallthesensorwirescangothrough.Temperatureprofileof
anemptysmokerwererecordedattwodifferentSetValues(150°Fand225°F),withthesmoke
generatorturnonoroff,andwiththecirculationfanturnonorturnoff.
Table1.Temperatureprofilerecordedintestsperformedinanemptysmoker.
Emptysmoker
Conditions
SetTemperature(°F) 150 225
CirculationFan off on off on off on off on
SmokeGenerator off off on on off off on on
ProbeReadings(°F)
1_Center 148 150 149 150 225 225 228 225
2_Center* 150 150 150 150 225 225 225 225
3_Center 151 151 151 151 226 226 228 225
4_Center 154 151 151 149 234 226 234 225
1_Back‐Left 151 155 153 152 242 228 234 228
1_Back‐Right 152 148 148 145 240 223 242 222
1_Front‐Left 144 146 161 152 219 218 221 219
1_Front‐Right 144 149 147 147 220 222 221 222
2_Back‐Left 153 160 153 153 235 239 228 238
2_Back‐Right 148 148 148 145 229 220 231 220
2_Front‐Left 147 149 159 151 223 223 224 222
2_Front‐Right 147 151 149 149 224 225 225 224
4_Back‐Left 150 154 154 154 232 231 230 232
4_Back‐Right 150 150 150 148 229 227 237 226
4_Front‐Left 149 151 153 150 227 228 227 223
4_Front‐Right 150 151 150 148 227 224 230 224
3_Wall_Center 155 148 148 146 240 221 236 221
3_Wall_Right 151 151 149 149 228 225 234 225
Statistics(overall)
Average 149.3
150.9 151.6 149.6 228.6 225.6 229.1 225
StandardDeviation 2.8 3.3 3.9 2.6 6.6 4.8 5.7 4.6
Range 11 14 14 9 23 21 21 19
Statistics(center)
Average 150.8
150.5 150.3 150 227.5 225.5 228.8 225
StandardDeviation 2.5 0.6 1 0.8 4.4 0.6 3.8 0
Range 6 1 2 2 9 1 9 0
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Figure3.AnimatedimageofthetemperaturedistributioninanemptysmokerwheretheSVissetat
150°Fandwiththesmokegeneratorturnedon.Thecolormapindicateshowmuchtheprobereadings
deviatesfromtheSV.Hotterareaisinredcolor,andcoolerareaisinbluecolor.Thedataisfromthe
3rdandthe4thcolumnsinTable1.Left:thecirculationfanwasturnedoff.Right:thecirculationfan
wasturnedon.
Figure4.AnimatedimageofthetemperaturedistributioninanemptysmokerwheretheSVissetat
225°Fandwiththesmokegeneratorturnedon.Thecolormapindicateshowmuchtheprobereadings
deviatesfromtheSV.Hotterareaisinredcolor,andcoolerareaisinbluecolor.Thedataisfromthe
lasttwocolumnsinTable1.Left:thecirculationfanwasturnedoff.Right:thecirculationfanwas
turnedon.
2)Smokerwithevenlyarrangedload
Inthisgroupoftests,cardboardsheetsofthesamesizewereplacedonallracksintosimulatesalmon
stripsinasmoker.Thetopventiscloseddowntoleave¼”gapsoallthesensorwirescangothrough.
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TemperatureprofileofthesmokerwererecordedattwodifferentSetValues(150°Fand225°F),with
thesmokegeneratorturnonoroff,andwiththecirculationfanturnonorturnoff.
Table2.Temperatureprofileofthesmokerwithevenlyarrangeload.
Smokerloadedwith28pcsofcardboardsheets
Conditions
SetTemperature(°F) 150 225
CirculationFan off on off on off on off on
SmokeGenerator off off on on off off on on
ProbeReadings(°F)
1_Center 150 150 154 153 227 226 232 227
2_Center* 150 150 150 150 225 225 225 225
3_Center 151 153 153 153 226 228 226 228
4_Center 148 151 148 150 223 228 225 226
1_Back‐Left 145 150 165 155 224 228 242 229
1_Back‐Right 149 146 145 145 224 224 230 220
1_Front‐Left 138 149 156 152 207 225 218 227
1_Front‐Right 141 149 145 150 211 224 213 224
2_Back‐Left 142 152 159 154 215 231 234 231
2_Back‐Right 142 145 146 144 216 219 217 218
2_Front‐Left 141 151 151 152 210 227 218 226
2_Front‐Right 141 150 146 151 213 226 216 226
4_Back‐Left 144 154 156 156 217 235 223 235
4_Back‐Right 143 150 145 149 215 227 216 225
4_Front‐Left 141 149 146 151 210 225 216 225
4_Front‐Right 142 150 144 149 211 225 215 224
3_Wall_Center 151 153 152 151 232 231 237 233
3_Wall_Right 146 149 148 149 222 227 220 225
Statistics(overall)
Average 144.3
149.9 150.6 150.9 217.1 226.4 222.9 226
StandardDeviation 4.1 2.2 6.1 3.2 6.7 3.4 8.3 3.9
Range 13 8 21 11 25 16 29 17
Statistics(center)
Average 149.8
151 151.3 151.5 225.3 226.8 227 226.5
StandardDeviation 1.3 1.4 2.8 1.7 1.7 1.5 3.4 1.3
Range 3 3 6 3 4 3 7 3
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Figure5.Animatedimageofthetemperaturedistributioninasmokerloadedwithequal‐sized
cardboardsheets.TheSVwassetat150°Fandthesmokegeneratorwasturnedon.Thecolormap
indicateshowmuchtheprobereadingsdeviatesfromtheSV.Hotterareaisinredcolor,andcooler
areaisinbluecolor.Thedataisfromthe3rdandthe4thcolumnsinTable2.Left:circulationfanwas
turnedoff.Right:circulationfanwasturnedon.
Figure6.Animatedimageofthetemperaturedistributioninasmokerloadedwithequal‐sized
cardboardsheets.TheSVwassetat225°Fandthesmokegeneratorwasturnedon.Thecolormap
indicateshowmuchtheprobereadingsdeviatesfromtheSV.Hotterareaisinredcolor,andcooler
areaisinbluecolor.ThedataisfromthelasttwocolumnsinTable2.Left:circulationfanwasturned
off.Right:circulationfanwasturnedon.
3)Randomlyplacedload
Inthisgroupoftests,weuseddifferentshapedanddifferentsizecardboardsheetsandboxesto
simulatingasituationwheredifferentsizeandtypeoffoodiscookedtogetherinasmoker.Cardboard
sheetsandboxeswererandomlyplacedonracksinthesmoker.Thetopventiscloseddowntoleave¼”
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gapsoallthesensorwirescangothrough.Temperatureprofileofthesmokerwererecordedattwo
differentSetValues(150°Fand225°F),withthecirculationfanturnonorturnoff,andwiththesmoke
generatorturnonoroff.
Table3.Temperatureprofileoftherandomlyloadedsmoker.
Smokerloadedwithrandomlyplacedcardboardboxes
Conditions
SetTemperature(°F) 150 225
CirculationFan off on off on off on off on
SmokeGenerator off off on on off off on on
ProbeReadings(°F)
1_Center
148 150 151 152 218 228 231 229
2_Center*
150 150 150 150 225 225 225 225
3_Center
145 153 149 151 216 230 228 228
4_Center
149 151 147 150 224 227 226 226
1_Back‐Left
150 149 144 153 215 227 260 229
1_Back‐Right
152 151 154 153 238 231 233 229
1_Front‐Left
142 148 144 149 209 223 220 224
1_Front‐Right
140 147 151 155 212 222 215 223
2_Back‐Left
153 151 144 153 222 232 254 231
2_Back‐Right
146 147 153 146 226 223 216 223
2_Front‐Left
141 150 144 151 206 228 220 227
2_Front‐Right
143 149 149 149 215 224 218 224
4_Back‐Left
147 153 141 155 215 235 246 225
4_Back‐Right
144 151 146 150 223 231 222 229
4_Front‐Left
141 150 137 150 208 226 218 227
4_Front‐Right
144 150 141 149 216 226 217 225
3_Wall_Center
149 149 144 148 219 226 229 225
3_Wall_Right
145 149 148 148 226 225 220 224
Statistics(overall)
Average
145.9 150 146.6 151 218 227.4 228.1 227
StandardDeviation
4.1 1.8 4.8 2.4 8.1 3.7 13.8 2.5
Range
13 6 17 9 30 13 45 8
Statistics(center)
Average
148 151 149.3 150.8 220.8 227.5 227.5 227
StandardDeviation
2.2 1.4 1.7 1 4.4 2.1 2.6 1.8
Range
5 3 4 2 9 5 6 4
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Figure5.Animatedimageofthetemperaturedistributioninasmokerloadedwithcardboardboxes
andsheetsofvarioussize.TheSVwassetat150°Fandthesmokegeneratorwasturnedon.Thecolor
mapindicateshowmuchtheprobereadingsdeviatesfromtheSV.Hotterareaisinredcolor,and
coolerareaisinbluecolor.Thedataisfromthe3rdandthe4thcolumnsinTable3.Left:circulation
fanwasturnedoff.Right:circulationfanwasturnedon.
Figure6.Animatedimageofthetemperaturedistributioninasmokerloadedwithcardboardboxes
andsheetsofvarioussize.TheSVwassetat225°Fandthesmokegeneratorwasturnedon.Thecolor
mapindicateshowmuchtheprobereadingsdeviatesfromtheSV.Hotterareaisinredcolor,and
coolerareaisinbluecolor.ThedataisfromthelasttwocolumnsinTable3.Left:circulationfanwas
turnedoff.Right:circulationfanwasturnedon.
4)Topventopen
Thisgroupoftestswasperformedtoseeifopeningthetopventwouldaffectthetemperatureprofilein
thesmoker.Thetopventwaseitherfullyopenorcloseddowntoleaveonlya¼”widegap,whichisto
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letsensorwirestorunthrough.Wekepttheloadatthesamepositionasinthegroup3.Testswere
performedattwodifferentSetValues(150°Fand225°F)andthecirculationfanwasturnedonorturned
off.Thesmokegeneratorwaskeptoninalltestsrunat225°F,butitturnedoffinalltestsrunat150°F
toreduceitseffectontemperature‐controlatlowtemperaturerange.
Table4.Temperatureprofilewhenthetopventwaschanged.
Randomlyplacedcardboardboxes
Conditions
SetTemperature(°F) 150 225
CirculationFan
off on off on off on off on
SmokeGenerator
off off off off on on on on
Vent 1/4" 1/4" open open 1/4" 1/4" open open
ProbeReadings(°F)
1_Center
146 151 148 150 229 225 228 224
2_Center*
150 150 150 150 225 225 225 225
3_Center
144 153 145 153 225 225 226 225
4_Center
149 151 149 151 230 225 231 225
1_Back‐Left
148 150 150 149 238 226 237 224
1_Back‐Right
157 151 152 151 223 221 224 221
1_Front‐Left
143 148 142 148 221 220 220 218
1_Front‐Right
143 148 140 147 220 221 219 220
2_Back‐Left
151 153 153 151 243 230 243 229
2_Back‐Right
150 148 146 147 223 218 223 218
2_Front‐Left
140 151 141 150 222 222 223 222
2_Front‐Right
144 149 143 149 224 224 224 224
4_Back‐Left
144 154 147 153 240 233 241 232
4_Back‐Right
148 152 144 151 225 226 225 226
4_Front‐Left
141 150 141 150 229 227 231 227
4_Front‐Right
145 151 144 150 224 222 224 222
3_Wall_Center
146 149 149 149 233 221 237 221
3_Wall_Right
149 150 145 149 226 224 225 225
Statistics(overall)
Average
146.4 150.6 145.9 150 227.6 224.4 227.8 223.9
StandardDeviation
4.4 1.8 4.1 1.8 7 3.8 7.1 3.7
Range
17 6 13 6 22 15 24 14
Statistics(center)
Average
147.3 151.3 148.0 151.0 227.3 225.0 227.5 224.8
StandardDeviation
2.8 1.3 2.2 1.4 2.6 0.0 2.6 0.5
Range
6 3 5 3 5 0 6 1
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Discussions
TheEffectoftheAirCirculationFan
TheresultsshowninTable1indicatesthatthetemperatureinanemptysmokerwasfairlyuniformeven
withoutacirculationfan.Turningonthecirculationfancanimprovetheevennessofthetemperature
distribution.
ThedatainTable2showsthattemperatureprofilebecamelessuniformwhenthesmokerwasloaded
withevenlyarrangedcarboardsheetsonallrackswhilethecirculationfanwasturnedoff.Thestandard
deviationincreasedby30%to50%comparetothestandarddeviationsinanemptysmoker.Afterthe
circulationfanwasturnedon,thestandarddeviationwasgreatlyreducedbynearly50%.Therangeof
thetemperaturedataalsodecreasedby30%to50%.
ThedatainTable3showsthatwhenthesmokerthatwasloadedwithrandomlyplacedcardboard
sheetsandcardboardboxesofvarioussize,thetemperaturedistributionbecameevenhigherwithno
circulationfan.Withthecirculationfanturnedon,thetemperaturedistributionissignificantlyreduced.
Thestandarddeviationswerereducedby50%orevenmoreofwhatitwaswithoutthecirculationfan.
Thetemperaturerangewasalsoreducedby50%or66%.
TheEffectofLoadsinasmoker
Wehaveaninterestingobservationinthestandarddeviations(SD)andtherangeofthedata.In
situationswherecirculationfanwasturnedoff,SDandtherangeofthedatainanemptysmokerare
usuallythelowestamongallthreeloadingconditions(i.e.,empty,loadedwithcardboardsheets,and
loadedwithcardboardboxes),andtheSDandrangeofdatainasmokerloadedwithcardboardboxesof
differentsizeareusuallythehighestamongallthreeconditions.Incontrast,inthesituationswherethe
circulationfanwasturnedon,theSDanddatarangeofanemptysmokerareusuallythehighestamong
allthreeloadingconditions,andtheSDanddatarangeofasmokerloadedwithcardboardboxesare
usuallythelowest.
Inasmokerwithoutforcedaircirculation,randomlyarrangecardboardboxesrestrainthenaturalair
flowandthereforeincreasethetemperaturedistribution.Whereasinasmokerwithforce‐air
circulation,therestraintontheair‐flowbythecardboardboxesiscounter‐actedbythecirculationfan.
Inthemeantime,wespeculatethatbecauseofasignificantportionofthevolumeinthesmokeris
occupiedbytheboxes,thereismuchlessairthatneedstobeheatedandcirculated,makingiteasierto
reachaneventemperaturedistribution.
TheEffectoftheTopVent
Duringourtests,openingorclosingthetopventdidn’tshowobviouseffectonthetemperatureprofile
inthesmoker.Theaverageandthestandarddeviationremainaboutthesamebetweenopenorclosed
topvent.Itisworthpointingoutthatourtestsweredoneinbalmysummerdays.Incoldwindydays,
theeffectofopeningthetopventcouldbedifferent.
TheLocationofTheWall‐MountSensor
Traditionallywemountawall‐mountprobe,onthecenterlineofthebackwallandjustunderneaththe
toprack,asthecontrolprobe.Inthisstudy,two“wall‐mount”probesareinstalled,“3_Wall_Center”
and“3_Wall_Right”.ThereadingsfromthesetwoprobeswerecomparedtotheSetValue(SV).The
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relativedifference(RD)betweenthewall‐mountprobe(T)andtheaveragereading(M
a
)wascalculated
usingtheformulabelow:
RD=(T–M
a
).
Thisvalueindicateshowmuchtheprobereadingdeviatesfromtheaveragetemperatureofthesmoker.
TheTable5summarizedthedifferenceofthewall‐mountprobeonthebackwallandthewall‐mount
probeonthesidewall.Inthemajorityoftests,thewall‐mountprobeontherightsideofthewallis
closertothesmoker’saveragetemperature.However,theairflowpatterninthesmokerdoesaffectthe
heatdistributioninthesmoker.Aswecanseeinthedatafromgroup#3intheTable4,thewall‐mount
sensoronthebackappeartobeclosertotheaverage.Butingeneral,thewall‐mountsensoronthe
rightisclosertothesmokeraverage.Therefore,insteadofmountthewall‐mountprobetothebackwall
ofthesmoker,wesuggestthewallmountsensortobemountedonthesidewallontherightjustunder
thetoprack(rack#4).
Table5.Thetemperaturereadingdifferencebetweenwall‐mountprobesandtheaveragetemperature
inthesmoker.
HeatProducedbytheSmokerGenerator
Tofindouttheeffectofthesmokegeneratoronthetemperatureprofileinthesmoker,welookedat
thedatafromsection#1,#2,and#3,andwecomparedthedatabetweentestswhenthesmoke
generatorwasturnedoffandwhenitwasturnedon.Withoutthecirculationfan,inmostofthecases
whenthesmokegeneratorwasturnedon(nosmokingbisquetteswasused),theaveragetemperature
increased,andthestandarddeviationaswellastherangeofthedataincreasedcomparingtothe
conditionswheresmokegeneratorwasturnedoff.Thisindicatesthatturningonthesmokegenerator
canbringuptheaveragetemperatureandreducethetemperatureuniformityinthesmoker.However,
whenthecirculationfanwasturnedonundereachtestingcondition,theSDandtherangeofthedata
weregreatlyreduced.
Difference
Conditions
SetTemperature(°F) 150 225
CirculationFan on on on on
SmokeGenerator off on off on
#1,Empty
3_Wall_Center
‐2.9 ‐3.6 ‐4.6 ‐4
3_Wall_Right
0.1 ‐0.6 ‐0.6 0
#2,Sheets
3_Wall_Center
3.1 0.14.6 7
3_Wall_Right
‐0.9‐1.9 0.6 ‐1
#3,Boxes
3_Wall_Center
‐1 ‐3 ‐1.4 ‐1.5
3_Wall_Right
‐1 ‐3 ‐2.4 ‐2.5
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Inwarmdays(70°Forhigher),smokingat150°Fcanbedifficultbecauseturningonthesmokegenerator
alonecancontribute125wattspower,thatisapproximately¼ofthe500wattselementcomeswiththe
BradleySmoker.AndthispartofpowerisnotregulatedbyourPIDcontroller.Theheaterinthesmoke
generatoralonecanraisethetemperaturebyalmost70°F.Theheatfromburningbisquettescan
increasethetemperaturebyanother20°F.Whensmokingatatemperaturethatisrelativelyclosetothe
ambienttemperature,theheatcontributedbythesmokegeneratorissignificant.Inaddition,because
theheaterofthesmokegeneratorislocatedatthebottom‐center,turningitonoroffcanchangethe
temperatureprofileinthesmoker.Inthissituation,theBradley’scoldsmokingadaptorshouldbeused.
Theothersolutionistorunitinthenightwhentemperatureislower,keepthetopventatthe
maximumopening.Runthesmokergeneratoratverybeginningfor1hourandthenturnitoff.
Conclusion
ThetemperatureprofileinaBradleyOriginal4‐rackelectricsmokerwastestedextensivelyundervaries
conditions.Thisstudydemonstratesthatasmokerthatreliesonnaturalconvection(gravityconvection)
canachieveareasonableeventemperaturedistributionwhenitisempty.Butoncethesmokerisloaded
withfood,thetemperatureprofilebecomesuneven.
Byaddingacirculationfantothesmoker,forced‐air‐convectionwasintroducedtothesmoker.Withthe
circulationfanturnedon,thestandarddeviationandtherangeofthetemperaturedataaresignificantly
reduced,whichmeansthetemperatureprofileinthesmokerhasbecomemoreuniform.Aninteresting
factisthat,withthecirculationfanrunning,theairtemperatureinthesmokerbecomesmoreeven
whenmorefoodinloadedtothesmoker.
Ifawall‐mountprobeisgoingtobeusedasthetemperaturecontrolprobe,itissuggestedtoavoidthe
hotairstreamfromthecirculationfan,andmountittotheothersideofthebackwall.
TheheatfromtheburnerofsmokergeneratorisnotregulatedbyAuber’sPIDcontroller.Itcanincrease
theaveragetemperatureinsidethesmokerandchangethetemperatureprofile.Whensmokingatlow
temperature(e.g.,150°Fforsalmon),wesuggestyouusea“coldsmokingadapter”whentheambient
temperatureisabove70°F.
Ourdatashowsthatleavingthetopventopenorclosedoesn’thaveasignificanteffectonthe
temperatureprofileinthesmokerinwarmdaysthatweperformedtests.
Theresultofcirculationfaninthisreportcouldbeappliedtootherbrandofsmokerswhenthesizeof
thesmokerandmountinglocationaresimilar.Thisstudydidnotincludethefanspeedandfansize
effecttothetemperatureprofile.Thatwillbepresentedonseparatereport.
(END)
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