Vim li cas cov fins ntawm lub finned tube heat exchanger muab tso rau ntawm sab uas tsis tshua muaj cua sov hloov coefficient?
Tso lus
Vim li cas cov fins ntawm lub finned tube heat exchanger muab tso rau ntawm sab uas tsis tshua muaj cua sov hloov coefficient?
Finned tube, tseem hu ua finned tube lossis finned tube, tseem hu ua "Fin Tube" lossis "Finned Tube" hauv lus Askiv, qee zaum hu ua "Extended Surface Tube", uas txhais tau hais tias lub raj txuas ntxiv. Raws li lub npe qhia, lub raj finned yog lub cim hloov hluav taws xob tsim los ntawm kev ua haujlwm ntau lub fins ntawm qhov chaw ntawm lub raj qub (txawm yog nyob rau sab nrauv lossis sab hauv), nthuav tawm qhov qub. Hauv qab no yog ob daim duab ntawm finned tubes. Vim li cas thiaj siv finned tubes? Dab tsi yog qhov cuam tshuam ntawm machining fins ntawm qhov chaw qub? Txhawm rau teb cov lus nug no, nws yog ib qho tsim nyog yuav tau pib nrog qee cov hauv paus ntsiab lus ntawm cov txheej txheem hloov hluav taws xob. Ua ntej, peb yuav tsum tau ua kom paub cov ntsiab lus hauv kev hloov hluav taws xob: kev hloov hluav taws xob ntawm cov khoom nto thiab cov kua hauv kev sib cuag nrog nws yog hu ua convective heat transfer. Kev hloov pauv cua sov uas peb paub zoo tshaj plaws yog kev hloov pauv cua sov ntawm sab nrauv ntawm lub tshuab hluav taws xob thiab cov huab cua. Kev paub hauv lub neej qhia peb tias qhov loj dua qhov chaw ntawm lub tshuab hluav taws xob, qhov kub ntawm qhov chaw siab dua (piv txwv li, qhov sib txawv ntawm qhov kub thiab txias ntawm huab cua ntau dua), thiab lub sij hawm cua sov ntev dua, qhov kub thiab txias dua. chav. Qhov no qhia tau hais tias convective heat transfer yog ncaj qha proportional rau tshav kub hloov chaw, kub sib txawv, thiab lub sij hawm. Yuav kom sib piv lub zog ntawm convective tshav kub hloov lwm lub tsev nyob rau hauv txawv tej yam kev mob, peb yuav tsum tau txhais lub cev muaj nuj nqi hu ua "heat transfer coefficient". Lub tshav kub hloov coefficient yog hais txog kev hloov pauv cua sov hauv ib cheeb tsam, ib chav tsev kub qhov sib txawv (kub qhov sib txawv ntawm phab ntsa thiab cov kua dej), thiab ib chav tsev lub sij hawm. Nws chav tsev yog J / (s. ㎡. degree) lossis W / (㎡. degree) Lub convective heat transfer coefficient feem ntau sawv cev los ntawm lub cim h. Qhov loj ntawm cov cua sov hloov coefficient feem ntau yog nyob ntawm cov hauv qab no: hom thiab lub cev lub zog ntawm cov kua dej: piv txwv li, dej thiab huab cua sib txawv kiag li, thiab lawv cov coefficients hloov hluav taws xob sib txawv heev; Puas yog cov kua dej nkag mus rau theem kev hloov pauv thaum lub sijhawm hloov hluav taws xob, piv txwv li boiling lossis condensation. Yog tias muaj kev hloov pauv theem tshwm sim, nws cov coefficient ntawm cov cua sov yuav nce siab heev; Nws kuj muaj feem xyuam rau qhov khiav ceev ntawm cov kua thiab cov duab ntawm cov khoom nto. Tos ib pliag. Qhov loj ntawm convective heat transfer coefficient yog txiav txim siab los ntawm kev tshawb fawb sim. Hauv qab no yog ib pawg ntawm cov zauv feem ntau siv: l condensation ntawm dej vapor: h=10000-20000 W/(㎡ * degree) l boiling dej: h=7000--10000,,, l convection ntawm dej: h{ {2}},,, l yuam convection ntawm huab cua los yog pa luam yeeb: h=30-50,,,, l natural convection ntawm huab cua los yog pa luam yeeb: h=3-5,,,,,, nws yuav pom tau hais tias qhov sib txawv ntawm qhov sib txawv ntawm cov cua sov coefficient nyob rau hauv cov xwm txheej sib txawv yog qhov tseem ceeb heev. Thov nco ntsoov cov naj npawb ntawm cov hluav taws xob hloov hluav taws xob uas tau hais los saum toj no, uas yog qhov tseem ceeb heev rau kev nkag siab thiab xaiv cov raj finned yav tom ntej. Hauv qab no, peb yuav tham txog ib qho piv txwv tshwj xeeb ntawm cov khoom siv hluav taws xob hloov hluav taws xob: lub tshuab hluav taws xob hloov hluav taws xob uas ua kom cua sov nrog dej kub, qhov dej kub ntws hauv cov yeeb nkab thiab cua ntws tawm sab nraud ntawm cov yeeb nkab.
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