小黑麦的水分含量对麦子自热以及筒仓舱壁压力的影响

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TIONOCCURREDINTHEUPPERANDTHELOWERPARTSOFTHESILO15ZHANGETAL24STUDIEDTHECHANGESINTHEVALUEOFPRESSUREQUOTIENTKINRELATIONTOTHEDISTANCEFROMTHESILOAXISANDTHEGRAINLAYERDEPTHUNDERTHEEFFECTOFSTATICANDTHERMALLOADSINSHALLOWANDDEEPSILOSTHEYANALYZEDSTRESSINCYLINDRICALGRAINSILOSUSINGTHEMODELOFSECONDGENERATIONTHEYAPPLIEDTHEANALYSISTOTWOGRAINSILOSONEWITHADIAMETEROF3AND9MHIGH,ANDANOTHEROF9MINDIAMETERAND9MHIGHBOTHWEREMADEOFCORRUGATEDSHEETMETALANDFILLEDWITHWHEATGRAINWITH10MOISTURECONTENTANDANINITIALBULKDENSITYOF801KGM3。INBOTHCASESTHEYDETERMINEDTHEMAINDIRECTIONOFSTRESSWITHINTHEGRAINMASSANDTHERATIOKOFLATERALTOVERTICALPRESSURETHEYFOUNDTHATNEITHERTHELATERALNORTHEVERTICALSTATICPRESSURESWEREUNIFORM,BUTDECREASEDINTHEDIRECTIONFROMSILOAXISTOWARDSTHEWALLSLATERALTHERMALPRESSURESINCREASEDWITHTHEINCREASINGDISTANCEFROMTHESILOAXIS,WHILETHEVERTICALTHERMALPRESSURESDECREASEDTHELATERALPRESSUREINCREASEDMORETHANTHEVERTICALWHENTHEGRAINTEMPERATUREDROPPEDTO30CTHELATERALPRESSUREINCREASECLOSETOTHESILOWALLWASMUCHSTRONGERTHANTHATATTHESILOAXISWHENTHETEMPERATUREDROPPEDTO30CCHANGESINTHEKRATIOVALUEWERESLIGHT,IRRESPECTIVEOFTHEDISTANCEFROMTHESILOAXISINTHECASEOFSTATICLOADS,BUTINCREASEDTO2063WITHTHETHERMALLOADSCHANGESINTHEKRATIOVALUEWERESLIGHTWHENREFERENCEDTOTHEGRAINLAYERDEPTHINSTATICLOADING,BUTDECREASEDBYANAVERAGE20FROMTHETOPTOTHEBOTTOMOFTHESILOINTHERMALLOADINGTHEAVERAGETHERMALVALUESOFKWEREHIGHERTHANTHESTATICSILOSAREUSUALLYFILLEDWITHGRAINOFAVARIEDMOISTURECONTENTGROCHOWICZETAL5ANDKUSISKA6,7STUDIEDTHEEFFECTOFTHEGRAINLAYERMOISTURECONTENTONTHEDISTRIBUTIONOFTEMPERATUREANDWATER,ANDONTHEPRESSURESEXERTEDBYTHEGRAINONTHESILOWALLSTHEYSHOWEDTHATINTERLAYERDIFFERENCESINTHEGRAINMOISTURECONTENTCAUSESTRONGINCREASESOFGRAINTEMPERATUREANDPRESSURESEXERTEDONTHESILOWALLSATTHEINTERLAYERBOUNDARIESTHEPROBLEMSPRESENTEDABOVEINDICATETHESTRONGNEEDFORSTUDIESONGRAINTEMPERATUREANDMOISTURECONTENT,ANDONTHEEFFECTOFTHOSEFACTORSONPRESSURESACTINGONSTRUCTURALELEMENTSOFSILOSCHANGESINPRESSURESCANBECAUSEDNOTONLYBYCHANGINGEXTERNALTEMPERATURETHEYAREALSOSTRONGLYAFFECTEDBYTHEINITIALMOISTURECONTENTOFTHEGRAIN,ASTHISAFFECTSTHEPROCESSOFMICROORGANISMSANDINSECTEVOLUTION,CAUSINGINCREASEDTEMPERATUREANDMOISTURECONTENTSCOPEANDMETHODTHESTUDYPRESENTSTHERESULTSOFMODELINVESTIGATIONSINVOLVINGMEASUREMENTSOFPRESSUREACTINGONSILOWALLSANDGRAINTEMPERATURETHEMATERIALUSEDWASTRITICALEGRAINWITHINITIALMOISTURECONTENTLEVELSOF13,16AND18WB,STOREDATACONSTANTEXTERNALTEMPERATUREOF15CFORAPERIODOF25DAYSAMOISTURECONTENTOF13,16OR18WBWASACHIEVEDBYTHEADDITIONOFADEQUATEWATERVOLUMEANDWASCALCULATEDBYTHEEQUATIONMWMGW2W1/100W23WHEREMWVOLUMEOFREQUIREDWATERADDITIONTOACHIEVETHEMOISTURECONTENTOFW2,KGMGMASSOFWATEREDGRAIN,KGW1INITIALGRAINMOISTURECONTENT,WBW2REQUIREDGRAINMOISTURECONTENT,WBWATEREDGRAINWASSTOREDINATIGHTLYCLOSEDBARRELFOR72HITWASROTATEDEVERYFEWHOURSTOEQUALIZETHEMOISTURECONTENTBEFORESTARTINGTHETEST,THEMOISTURECONTENTWASCONTROLLEDASCHEMATICDIAGRAMOFTHETESTSTANDISPRESENTEDINFIG1THEMAINELEMENTWASTHESILO1WHICHWASPROVIDEDWITHAWATERJACKETTHEEXTERNALDIAMETEROFTHESILOWAS600MMANDITSHEIGHTWAS1200MMTHEWATERJACKETWASSUPPLIEDWITHWATERATAREQUIREDTEMPERATURE,THEWATERTEMPERATUREBEINGCONTROLLEDBYMEANSOFANULTRATHERMOSTAT6THESILOWASFILLEDWITHTRITICALEGRAINOFASPECIFICINITIALMOISTURECONTENTINALLTHEEXPERIMENTSTHEINITIALGRAINTEMPERATUREWASTHESAMEAT15CTHEN,THEINITIALPRESSUREAGAINSTTHESILOWALLWASMEASUREDATEIGHTHEIGHTLEVELSABOVETHESILOBOTTOM175,275,375,475,575,675,775AND875MMDURINGTHEEXPERIMENTS,THEPRESSUREVALUESWEREMEASUREDONCEADAYBYMEANSOFSTRAINGAUGES4ANDAFORCEGAUGETYPEAPARAR9235ATTHESAMETIMETHEGRAINTEMPERATUREINSIDETHESILOWASMEASUREDAT40MEASUREMENTPOINTSBYMEANSOFTHERMOCOUPLES2ANDATEMPERATUREGAUGETYPEAR5923THETEMPERATUREMEASUREMENTPOINTSWERELOCATEDATTHESAMEHEIGHTASTHESTRAINGAUGES,ATDISTANCESFROMSILOAXISOF0,75,150,225AND300MMSTRAINGAUGESATAMEASURINGRANGEOF1AND2NANDAMEASURINGACCURACYOF001NWEREUSEDSTEELPISTONSWITHADIAMETEROF25MMWEREATTACHEDTOTHEGAUGINGPOINTANDTHEGRAINWASPRESSURIZEDTHROUGHATHINRUBBERMEMBRANEFIG1SCHEMATICDIAGRAMOFTHETESTSTATION1SILO,2THERMOCOUPLES,3TEMPERATUREGAUGES,4STRAINGAUGES,5SILOWALLLOADINDICATORWITHAMPLIFIER,6THERMOSTATITWASCALCULATEDBYTHEEQUATIONPF/S4WHEREPGRAINPRESSUREONTHEWALL,PAFGRAINPRESSUREFORCE,NSPISTONSSURFACE,M2THESTRAINGAUGESWEREATTACHEDTOTHEWALLWITHTHEBRACKETTHEMEASURINGSYSTEMWASCALIBRATEDBYASTATICMETHODBEFOREEVERYBATHOFTHESILOTEMPERATUREMEASUREMENTWASCARRIEDOUTTOWITHINANACCURACYOF01ALLMEASUREMENTSWERETAKENINTHREEREPLICATIONSRESULTSTHEMEANVALUESOFTHEPRESSUREANDTEMPERATUREMEASUREMENTSAREPRESENTEDINFIGS2AND3INALLCASESTHEINITIALTEMPERATUREOFTHETRITICALEGRAINPUTINTHESILOWAS15CINTHECOURSEOFSTORAGE,THEGRAINTEMPERATUREREACHEDTHEHIGHESTVALUESATTHESILOAXIS,ANDTHATISWHYTHEDIAGRAMSILLUSTRATETEMPERATURECHANGESATMEASUREMENTPOINTSLOCATEDALONGTHEAXISTHETEMPERATUREOFTRITICALEGRAINWITHANINITIALMOISTURECONTENTOF13WBINCREASEDWITHTHEPASSAGEOFSTORAGETIMETHESTRONGESTINCREASEINTEMPERATUREWASOBSERVEDATMEASUREMENTPOINTSLOCATEDATTHEHEIGHTOF675AND775MMABOVETHESILOBOTTOMAFTER25DAYS,THEGRAINTEMPERATUREATTHOSELEVELSWAS22CAMUCHHIGHERINCREASEINGRAINTEMPERATUREWASRECORDEDFORTHETRITICALEGRAINWITHANINITIALMOISTURECONTENTOF16WBFIG2THESTRONGESTCHANGESINTEMPERATUREOCCURREDDURINGTHEPERIODUPTODAY20OFTHESTORAGEATAHEIGHTOF675MMTHETEMPERATUREVALUEREACHED36CANDTHELOWESTMEASUREMENTPOINT30CBETWEENDAY20ANDDAY25,CHANGESINTEMPERATUREWEREONLYSLIGHTTHETEMPERATUREINCREASEDBY2DEGREES,MAINLYINTHELOWERPARTOFTHESILOTHEHIGHESTTEMPERATUREVALUESWEREOBSERVEDINTHECASEOFTHETRITICALEGRAINWITHTHEINITIALMOISTURECONTENTOF18WBFIG2THEMAXIMUMVALUEOBSERVEDAFTER25DAYSWASATAHEIGHTOF675MM44CATTHATTIMETHETEMPERATUREATTHEBOTTOMOFTHESILOWAS36CATTHISMOISTURECONTENT,THETEMPERATUREINCREASEWASALSOTHESTRONGESTUNTILDAY20OFSTORAGEINALLTHEEXPERIMENTSTHETEMPERATUREATTHEHIGHESTMEASUREMENTLEVELWASLOWERTHANATHEIGHTSOF675AND775MMTHISWASDUETOWATEREVAPORATIONTHEFACTTHATTHEHIGHESTTEMPERATURESWEREOBSERVEDATHEIGHTSOF675AND775MMINDICATESWATERDIFFUSIONFROMTHEBOTTOMTOWARDSTHETOPOFTHESILO,ANDITSABSORPTIONMAINLYATTHOSELEVELSTEMPERATUREATTHESILOWALLWASLOWERTHANATPOINTSLOCATEDONTHESILOAXISAFTER25DAYSOFSTORAGEBYANAVERAGEOF25DEPENDINGONTHEGRAINMOISTURECONTENTTHEMEANVALUEOFTRITICALEGRAINMOISTURECONTENTINCREASEDBY05INTHEFIRSTCASE,12INTHESECOND,ANDBYABOUT21INTHETHIRDINCREASEDMOISTURECONTENTCAUSEDCHANGESINTHEVALUEOFPRESSUREONTHESILOWALLTHELOWESTINCREASESINSILOWALLPRESSUREWEREOBSERVEDINTHECASEOFTRITICALEGRAINWITHAMOISTURECONTENTOF13WBWHENTHESILOWASFILLED,THEWALLPRESSUREINTHELOWERPARTOFTHESILOWAS918HPA,ANDATTHEHIGHESTMEASUREMENTLEVELITWAS206HPAAFTER25DAYSOFSTORAGETHOSEVALUESINCREASEDTO107AND22HPA,RESPECTIVELYTHEINITIALWALLPRESSUREOFTHETRITICALEGRAINWITH16WBMOISTURECONTENTWAS89HPAATTHEBOTTOMAND18HPAATTHETOPTHELOWERPRESSUREVALUESWHENCOMPAREDTOTHOSEFORTRITICALEGRAINWITH13WBMOISTUREWEREDUETOTHELOWERBULKDENSITYINTHECOURSEOFTHESTORAGEPERIOD,PRESSUREVALUESGREWGRADUALLYTOREACHTHEIRMAXIMUM,ATTHEFINALSTAGEOFSTORAGE121HPAATTHEBOTTOMAND24HPAATTHETOPTHEHIGHESTPRESSUREINCREASEWASOBSERVEDFROMTHEBOTTOMOFTHESILOUPTOAHEIGHTOF775MMATAHEIGHTOF885MM,THEINCREASEINWALLPRESSUREWASONLYSLIGHTEFFECTOFTHETRITICALEGRAINMOISTUREFIG2THEEFFECTOFSTORAGEDURATIONONTHETEMPERATUREOFTRITICALEGRAINWITHMOISTURECONTENT13WBA,16WBB,AND18WBCFIG3PRESSUREVALUESFORTRITICALEGRAINWITHMOISTURECONTENT13WBA,16WBB,AND18WBCTHEHIGHESTINCREASEINWALLPRESSUREVALUESWASOBSERVEDINTHECASEOFTHETRITICALEGRAINWITHA18WBMOISTURECONTENTONTHEFIRSTDAYOFSTORAGETHEPRESSUREWAS85HPAATTHEBOTTOMAND16HPAATTHETOPOVER5DAYS,THEPRESSUREINCREASEDONLYSLIGHTLY,WITHTHEEXCEPTIONOFTHEVALUERECORDEDATAHEIGHTOF775MM,WHEREITREACHED73HPAATTHATTIME,THEWATERACCUMULATIONINCREASEINTHEMATERIALSTOREDBECAMEAPPARENTBETWEENDAY5ANDDAY10,ARAPIDINCREASEINPRESSUREVALUESWASOBSERVED,UPTOTHEVALUEOF152HPAATTHEBOTTOMOFTHESILOEXTENSIONOFSTORAGETIMEBEYONDDAY10UPTODAY25CAUSEDVERYLITTLEINCREASEINTERMSOFWALLPRESSUREINTHELOWERPARTOFTHESILO,UPTO475MM,ANDADECREASEINPRESSUREABOVETHATLEVEL,WHICHISCONSISTENTWITHGRAINMILDEWINGCONCLUSIONS1THEINITIALMOISTURECONTENTOFTRITICALEGRAINAFFECTSTHETEMPERATUREOFGRAININSTORAGEANDTHEPRESSUREEXERTEDBYTHEGRAINONTHESILOWALL2THEHIGHESTTEMPERA