Ukudluliselwa kobushushu beConvection kwiinkqubo zokupholisa iinjini
Inkqubo yokupholisa injini yenye yezona nkqubo zibalulekileyo ekugcineni ukusebenza kakuhle kwenjini, ukusebenza kakuhle kwayo, kunye nobude bayo—nokuba kusezimotweni, kwiijenereyitha, kwiimashini zoshishino, okanye kwezinye iimashini ezivelisa ubushushu obuphezulu. Xa injini isebenza, ukutsha kwamafutha kunye nokungqubana phakathi kwezinto zangaphakathi kuvelisa ubushushu obuninzi. Ukuba obu bushushu abulawulwa, amaqondo obushushu enjini anokunyuka ngaphaya kwemida ekhuselekileyo, nto leyo ekhokelela ekuncipheni kokusebenza, umonakalo we-lubricant, ukuguquka kwamacandelo, kwanokusilela kwenjini. Kulapho ukudluliselwa kobushushu, ingakumbi i-convection, kudlala indima ebalulekileyo.
Iingcamango eziSiseko zoThutho lobushushu
Ngokubanzi, ukudluliselwa kobushushu kwenzeka ngeendlela ezintathu: ukuhanjiswa komoya, ukuhanjiswa komoya, kunye nokukhanya. Kwiinkqubo zokupholisa iinjini, zonke ezi zintathu zenzeka ngaxeshanye, kodwa ukuhanjiswa komoya kudla ngokuba "ngumdlali ophambili" kuba kubandakanya ukuhamba kolwelo (ulwelo okanye iigesi) ezithwala ubushushu ukusuka kwenye indawo ukuya kwenye.
– Ukuqhuba: ukudluliselwa kobushushu kwizinto eziqinileyo, umzekelo ukusuka eludongeni lwesilinda ukuya emanzini ejakethi.
– Ukudluliselwa kobushushu: ukudluliselwa kobushushu phakathi komphezulu oqinileyo kunye nolwelo oluhambayo, umzekelo ukusuka eludongeni lwenjini ukuya kwi-coolant, okanye ukusuka kwiiphiko ze-radiator ukuya emoyeni.
– Ukukhanya: ukukhutshwa kwamandla obushushu ngamaza e-electromagnetic, umzekelo ukusuka kumphezulu wenjini eshushu ukuya kwindawo engqongileyo.
Ngelixa ukuhanjiswa kombane kudibanisa ubushushu obuvela ngaphakathi kwenjini ukuya kwiindawo ezidibene nolwelo, ukuhanjiswa kombane kumisela ukuba ubushushu buthuthwa kwaye bususwe ngempumelelo kangakanani.
Inkcazo kunye nendlela yokuguqula i-Convection
I-Convection kukudluliselwa kobushushu okwenzeka ngenxa yokudibana kweenkqubo ezimbini: (1) ukusasazwa kobushushu (ukuhanjiswa) kumaleko wolwelo okufutshane kakhulu nomphezulu, kunye (2) ukudluliselwa kobuninzi bolwelo ngokwalo (i-advection) oluthwala amandla obushushu. I-Convection ingahlulwahlulwa ibe:
1. Ukuhanjiswa kwendalo
Oku kwenzeka ngenxa yokwahluka koxinano ngenxa yokwahluka kobushushu. Ulwelo olushushu luyakhaphukhaphu luze lunyuke, ngelixa ulwelo olubandayo lutshona. Umzekelo ngumoya ohambahamba kwinjini eshushu nokuba ingenafeni.
2. Uxinzelelo olunyanzelekileyo
Oku kwenzeka xa ulwelo lushukunyiswa sisixhobo sangaphandle esifana nepompo okanye ifeni. Kwiinkqubo zokupholisa iinjini zanamhlanje, i-convection enyanzelisiweyo iphambili: i-coolant ipompelwa ijikeleze ibhloko yenjini, kwaye umoya uphoqeleka ukuba udlule kwi-radiator yifeni kunye nokuhamba okubangelwa kukuhamba kwesithuthi.
Ngokwezibalo, izinga lokudluliselwa kobushushu obuguquguqukayo lidla ngokubonakaliswa nge-equation elula:
\[
Q = hA(T_s – T_\infty)
\]
apho u-Q lizinga lobushushu (W), u-h yi-convection heat transfer coefficient (W/m²K), u-A yindawo yomphezulu woqhagamshelwano (m²), u-T yiqondo lobushushu lomphezulu, kwaye u-T yiqondo lobushushu lolwelo kude nomphezulu.
Ixabiso le-h libalulekile kuba lichaza amandla enkqubo okudlulisa ubushushu nge-convection. Eli xabiso lichaphazeleka yisantya sokuhamba kolwelo, uhlobo lolwelo, iimpawu zomzimba (i-viscosity, i-thermal conductivity), kunye neempawu zokuhamba (i-laminar okanye i-turbulent).
Indima yeConvection kwiiNkqubo zokupholisa ulwelo
Kwiinjini ezininzi, ukupholisa kwenziwa lulwelo olupholisa umoya (umxube wamanzi kunye ne-antifreeze) olujikeleza kwiindlela ezijikeleze ii-cylinder kunye neentloko zee-cylinder. Le nkqubo ingachazwa njengoluhlu lweenkqubo zokudlulisa ubushushu:
1. Ubushushu obuvela kwigumbi lokutsha kunye neendonga zesilinda budluliselwa ngokuhambisa ukuya kumphezulu wodonga odibene nesipholisi.
2. Ukujikeleza komoya ukusuka eludongeni lwenjini ukuya kwi-coolant kwenzeka xa i-coolant idlula kwi-water jacket. Okukhona ukuhamba komoya kukhawulezayo kwaye kuguquguqukayo, kokukhona i-convection coefficient iphezulu.
3. I-hot coolant ingena kwi-radiator, apho ubushushu bukhutshwa khona emoyeni.
Kukwesi sigaba sesibini apho i-convection isebenza njengeyona ndlela iphambili "yokuthutha". Iipayipi zokupholisa kwibhloko yenjini zihlala zenzelwe ukugcina isantya sokuhamba esiphakathi. Ukuxinana okulawulwayo kunokuphucula ukudluliselwa kobushushu, nangona ukuxinana okugqithisileyo kunokunyusa ukulahleka koxinzelelo kunye noxinzelelo kwimpompo.
I-Convection kwiiRadiators: Ukusuka kwi-Cooler ukuya kwi-Air
I-radiator isebenza njengesitshintshi sobushushu phakathi kwe-coolant nomoya wangaphandle. Ngaphakathi kwi-radiator kukho imibhobho emincinci kunye namaphiko okwandisa indawo yomphezulu. Inkqubo:
– I-coolant eshushu ihamba kwimibhobho ye-radiator; ubushushu budluliselwa ukusuka kwi-coolant ukuya eludongeni lwemibhobho nge-convection yangaphakathi.
– Ubushushu bungena kwiindonga zepayipi (umqhubi).
– Ubushushu budluliselwa ukusuka kumphezulu ongaphandle wemibhobho kunye namaphiko ukuya emoyeni ojikelezileyo nge-convection yangaphandle.
Ukudluliselwa kobushushu kuya kwanda ukuba:
– Indawo enkulu esebenza kakuhle (amaphiko axineneyo kunye noyilo olufanelekileyo),
– Umoya ohambayo kakhulu (imoto ehambayo okanye ifeni yeradiator isebenza),
– Coca umphezulu (ukungcola, uthuli, okanye izinambuzane zinokuthintela ukuhamba kwamanzi kwaye zinciphise ukusebenza kakuhle).
I-convection yomoya-ukuya-emoyeni idla ngokuba ne-coefficient ephantsi yokudlulisa ubushushu kune-convection yolwelo kuba umoya une-thermal conductivity ephantsi. Ke ngoko, ii-radiator zifuna amaphiko kunye nomoya onamandla ngokwaneleyo ukuze zikhuphe ubushushu ngokwaneleyo.
Izinto Ezichaphazela Ukusebenza Kokujika Kwe-Convection
Ezinye zezinto eziphambili ezimisela ukusebenza kakuhle kwe-convection kwinkqubo yokupholisa injini ziquka:
1. Izinga lokuhamba kolwelo
Ukunyusa isantya sokuhamba kwamanzi kudla ngokunyusa i-convection coefficient (h). Kwi-coolant, ipompo yamanzi iqinisekisa ukuhamba okuzinzileyo. Emoyeni, isantya sefeni kunye nesithuthi simisela isantya sokuhamba kwamanzi kwi-radiator.
2. Iimpawu zolwelo olupholisayo
Isibandisi asingomanzi nje kuphela; sidla ngokuncediswa nge-ethylene glycol okanye i-propylene glycol ukuphakamisa iqondo lokubila, ukunciphisa iqondo lokubanda, nokuthintela ukugqwala. Nangona kunjalo, i-glycol eninzi kakhulu inokunciphisa amandla athile obushushu kwaye yonyuse i-viscosity, nto leyo enokuchaphazela ukudluliselwa kobushushu kunye nokusebenza kwepompo.
3. Inkqubo yokugeleza kwamanzi (i-laminar vs i-turbulent)
Ukuhamba kwamanzi okuguqukayo kwandisa ukuxubana, kunciphise umaleko womda wobushushu kwaye kwandisa ukudluliselwa kobushushu. Iindidi ezininzi zemibhobho kunye neeradiator ziyayisebenzisa ngokukhuselekileyo le meko.
4. Iimeko zomphezulu kunye nokungcola
Isikali, umhlwa, okanye iidiphozithi kwimigca yesipholisi kunye neradiyetha zinokusebenza njengezithinteli zobushushu kwaye zinciphise ukudluliselwa kobushushu. Kwicala lomoya, iifin ezivalekileyo zinciphisa ukuhamba komoya kwaye ziphazamise ukujikeleza komoya.
5. Umahluko kubushushu (amandla okuqhuba)
Okukhona umahluko omkhulu kubushushu phakathi komphezulu oshushu kunye nolwelo, kokukhona amathuba okudluliselwa kobushushu aphezulu. Ke ngoko, i-thermostat idlala indima ekugcineni injini ikwiqondo lobushushu elifanelekileyo lokusebenza: ishushu ngokwaneleyo ukuze itshise kakuhle, kodwa ayishushu kakhulu kangangokuba ishushu kakhulu.
I-Convection kwiiNkqubo zoKupholisa umoya
Ezinye iinjini zisebenzisa ukupholisa umoya, ingakumbi iinjini ezincinci okanye ezo zinemizobo elula. Kule nkqubo, ubushushu bususwa kumphezulu wenjini ngokusebenzisa amaphiko andisa indawo yomphezulu. Ukuguqulwa komoya kwenzeka ukusuka kumaphiko ukuya emoyeni, nokuba ngokwendalo okanye ngokunyanzelwa ngoncedo lomtshisi okanye ifeni.
Impumelelo yokupholisa umoya ixhomekeke kakhulu kwezi zinto zilandelayo:
– uyilo lwephiko (ubukhulu, isithuba, kunye nommandla womphezulu),
– indlela kunye nesantya sokuhamba komoya,
– ukucoceka komphezulu wephiko.
Ngenxa yokuba umoya unomthamo ophantsi wokuthwala ubushushu kunezinto ezisetyenziswayo, ukupholisa umoya ngokuqhelekileyo kufanelekile kwimithwalo emincinci yobushushu okanye usetyenziso olungadingi lawulo lobushushu oluchanekileyo njengokupholisa ulwelo.
Ukubaluleka kweConvection ukuze kuqinisekiswe ukuba umatshini uthembekile
Ubushushu benjini obusebenzayo bugcina ubushushu benjini bukwinqanaba elikhuselekileyo. Amaqondo obushushu aphezulu kakhulu anokubangela oku kulandelayo:
- ukungqongqoza kunye nokuncipha kokusebenza kakuhle,
– ukonakala kweoyile yokuthambisa,
– umonakalo kwiigaskets kunye neetywina,
– imingxunya entloko yesilinda,
– ukwanda kokuguguleka kwezixhobo.
Kwelinye icala, injini ebanda kakhulu nayo ayifanelekanga, kuba ibangela ukutsha okungasebenzisi kakuhle, ukusetyenziswa kwepetroli okwandileyo, kunye nokukhutshwa komoya okwandileyo. Ke ngoko, inkqubo yokupholisa kufuneka ikwazi ukulawula ngokuguquguqukayo ukuhanjiswa komoya ngokweemeko zokusebenza.
Ukuvala
Ukudluliselwa kobushushu be-Convection kusembindini wendlela esebenza ngayo inkqubo yokupholisa yenjini. Ukusuka kwijakethi yamanzi engaphakathi kwebhloko yenjini ukuya kwi-radiator esasaza ubushushu emoyeni, i-convection imisela ukuba ubushushu bungathuthwa kwaye buphele ngokukhawuleza kangakanani. Ukusebenza kwayo kuphenjelelwa lizinga lokuhamba kolwelo, iimpawu ze-coolant, uyilo lwe-channel kunye ne-fin, kunye nokucoceka kwenkqubo. Ngokuqonda ingcamango ye-convection kunye nezinto eziyichaphazelayo, abayili beenjini banokuphucula ukusebenza kokupholisa, kwaye abasebenzisi banokwenza ulondolozo olufanelekileyo ukuqinisekisa ukusebenza kwenjini okuzinzileyo, okusebenzayo, nokuhlala ixesha elide.
Ukuba unqwenela, ndingongeza nomfanekiso womsebenzi wenkqubo yokupholisa, umzekelo olula wokubala usebenzisa i-convection equation, okanye ndithelekise ukusebenza kwe-radiator ngokusekelwe kutshintsho kwisantya sefeni kunye nendawo ye-fin.
