Thermal conductivity ntawm pob zeb: nta, coefficient thiab rooj

2024 Tus sau: Howard Calhoun | [email protected]. Kawg hloov kho: 2024-01-17 18:53

Ib yam tseem ceeb tshaj plaws ntawm cov pob zeb, tau kawg, yog nws cov thermal conductivity. Qhov ntsuas no tuaj yeem sib txawv heev rau ntau hom khoom. Lub thermal conductivity ntawm pob zeb yog feem ntau nyob ntawm hom muab tub lim siv hauv nws. Cov khoom siv sib dua, qhov zoo dua cov insulator los ntawm qhov txias.

Dab tsi yog thermal conductivity: txhais

Cov ntaub ntawv sib txawv tuaj yeem siv rau hauv kev tsim vaj tsev thiab cov qauv. Cov vaj tsev nyob thiab kev lag luam hauv Lavxias kev nyab xeeb feem ntau yog insulated. Ntawd yog, thaum lawv tsim kho, tshwj xeeb insulators yog siv, lub hom phiaj tseem ceeb ntawm kev tswj hwm qhov kub thiab txias hauv qhov chaw. Thaum xam tus nqi ntawm cov ntxhia wool lossis polystyrene ua npuas ncauj, cov thermal conductivity ntawm cov khoom siv hauv paus siv rau kev tsim kho ntawm cov txheej txheem enclosing.

Ntau zaus, cov tsev thiab cov qauv hauv peb lub tebchaws tau tsim los ntawm ntau hom pob zeb. Cib thiab ntoo kuj siv rau lub hom phiaj no. Qhov tseeb, thermal conductivity nws tus kheej yog lub peev xwm ntawm cov khoom siv los hloov lub zog hauv nws cov tuab vim qhov txav ntawm cov molecules. Muscov txheej txheem zoo sib xws tuaj yeem, ob qho tib si hauv cov khoom ntawm cov khoom, thiab hauv nws qhov pores. Nyob rau hauv thawj rooj plaub, nws yog hu ua conduction, nyob rau hauv lub thib ob - convection. Qhov txias ntawm cov khoom yog sai dua nyob rau hauv nws cov khoom. Cua ntim cov pores ntxiab cua sov, tau zoo dua.

Dab tsi txiav txim siab qhov taw qhia

Cov lus xaus los ntawm cov saum toj no tuaj yeem kos tau raws li hauv qab no. Lub thermal conductivity ntawm pob zeb, ntoo thiab cib, zoo li lwm yam khoom siv, nyob ntawm lawv:

• density;
• porosity;
• humidity.

Nrog rau qhov nce ntawm qhov ntom ntawm cov pob zeb, cov qib ntawm nws cov thermal conductivity kuj nce. Qhov ntau pores nyob rau hauv cov khoom, qhov zoo insulator los ntawm txias nws yog.

Types of concrete

Hauv kev tsim kho niaj hnub no, ntau hom khoom siv tau siv tau. Txawm li cas los xij, tag nrho cov pob zeb uas muaj nyob hauv khw tuaj yeem faib ua ob pawg loj:

• hnyav;
• lub teeb foamy lossis nrog ntxeem tau ntim.

Thermal conductivity ntawm hnyav pob zeb: ntsuas

Cov ntaub ntawv no kuj muab faib ua ob pawg loj. Pob zeb siv tau hauv kev tsim kho:

• hnyav;
• tshwj xeeb hnyav.

Hauv kev tsim cov khoom siv thib ob, cov khoom siv xws li cov hlau seem, hematite, magnetite, barite yog siv. Tshwj xeeb tshaj yog cov pob zeb hnyav feem ntau tsuas yog siv hauv kev tsim kho cov chaw uas nws lub hom phiaj tseem ceeb yog kev tiv thaiv hluav taws xob. Cov pab pawg no suav nrog cov khoom siv nrog qhov ntom ntawm 2500 kg / m 3.

Cov pob zeb hnyav hnyav yog tsim los siv cov khoom siv xws li granite, diabase lossis limestone, ua los ntawm cov pob zeb crushed. Hauv kev tsim cov tsev thiab cov qauv, cov khoom siv zoo sib xws nrog qhov ntom ntawm 1600-2500 kg / m yog siv^3.

Dab tsi tuaj yeem yog qhov thermal conductivity ntawm pob zeb hauv qhov no? Cov lus hauv qab no qhia txog kev ua tau zoo ntawm ntau hom khoom hnyav.

Thermal conductivity ntawm hnyav pob zeb

Type of concrete	xwb heev	Hnyav rau RC cov qauv	Nyob rau hauv xuab zeb
Thermal conductivity W/(m°C)	1, 28-1, 74	Ntawm qhov ntom 2500kg / m3 - 1.7	Ntawm qhov ceev 1800-2500 kg / m3 - 0.7

Thermal conductivity ntawm lub teeb yuag cellular pob zeb

Cov khoom no kuj tau muab faib ua ob hom loj. Feem ntau, cov pob zeb ua los ntawm cov porous muab tub lim yog siv hauv kev tsim kho. Raws li yav tas los, nthuav av nplaum, tuff, slag, pumice yog siv. Hauv pab pawg thib ob ntawm cov pob zeb sib sib zog nqus, siv cov khoom siv tsis tu ncua. Tab sis nyob rau hauv tus txheej txheem ntawm kneading, xws li cov ntaub ntawv foams. Yog li ntawd, tom qab maturation, nws tseem tshuav ntau qhov pores.

Thermal conductivity ntawm lub teeb yuag pob zeb yog tsawg heev. Tab sis nyob rau tib lub sij hawm, nyob rau hauv cov nqe lus ntawm lub zog yam ntxwv, xws li cov khoom yog inferior rau ib tug hnyav. Lub teeb yuag yog siv feem ntau rau kev tsim kho ntawm ntau hom vaj tse thiaboutbuildings uas tsis raug hnyav loads.

Lub teeb pob zeb tau faib tsis yog los ntawm txoj kev tsim khoom, tab sis kuj yog lub hom phiaj. Hauv qhov no, muaj cov ntaub ntawv:

• tshav kub-insulating (nrog qhov ntom txog 800 kg / m3);
• cov qauv thiab cov rwb thaiv tsev kub (txog 1400 kg / m3);
• qauv (txog 1800 kg / m3).

Cov thermal conductivity ntawm cellular lightweight qhob ntawm ntau hom yog nthuav tawm nyob rau hauv lub rooj.

Lub teeb pob zeb: thermal conductivity ntsuas

Type of concrete	tshav kub-insulating	qauv thiab thermal rwb thaiv tsev	Kev tsim kho
Ntau tshaj qhov tso cai thermal conductivity W / (m ° C)	0, 29	0, 64	tsis yog tus qauv

cov khoom siv hluav taws xob kub

Cov pob zeb zoo li no feem ntau yog siv rau cov phab ntsa hauv ob sab phlu los ntawm cov cib lossis nchuav los ntawm cov cement mortar. Raws li tuaj yeem pom los ntawm lub rooj, cov thermal conductivity ntawm pob zeb ntawm cov pab pawg no tuaj yeem sib txawv ntawm ntau qhov loj.

Thermal conductivity ntawm lightest concretes

khoom	Aerated concrete	nthuav pob zeb
Thermal conductivity W/(m°C)	0, 12-0, 14	0, 23-0, 4

Qhob ntawm ntau yam no feem ntau sivraws li cov ntaub ntawv insulating. Tab sis qee zaum ntau yam tsis tseem ceeb lub tsev hnab ntawv tau tsim los ntawm lawv.

Cov qauv, cov khoom siv hluav taws xob thiab cov khoom siv hluav taws xob

Los ntawm pab pawg no, ua npuas ncauj ua npuas ncauj, slag-pumice pob zeb, slag qhob feem ntau siv hauv kev tsim kho. Qee hom ntawm cov av nplaum nthuav dav nrog qhov ceev tshaj 0.29 W / (m ° C) kuj tuaj yeem raug ntaus nqi rau ntau yam no.

Cov qauv ua vaj tse: thermal conductivity

khoom	Aerated concrete	Slag pumice concrete	Slag concrete
Thermal conductivity	0.3W/(m°C)	Up to 0.63 W/(m°C)	0.6W/(m°C)

Ntau zaus xws li pob zeb uas tsis tshua muaj thermal conductivity yog siv ncaj qha los ua cov khoom siv hauv tsev. Tab sis qee zaum nws kuj tseem siv los ua cov insulator uas tsis txhob cia txias dhau.

Yuav ua li cas thermal conductivity nyob ntawm cov av noo

Txhua tus paub tias yuav luag txhua yam khoom siv qhuav insulates los ntawm qhov txias zoo dua li ntub dej. Qhov no feem ntau yog vim qhov qis heev ntawm thermal conductivity ntawm dej. Lawv tiv thaiv cov phab ntsa, hauv pem teb thiab qab nthab los ntawm qhov kub thiab txias sab nraum zoov, raws li peb pom, feem ntau yog vim muaj huab cua puv pores hauv cov khoom. Thaum ntub, tom kawg yog hloov los ntawm dej. Thiab, yog li ntawd, lub coefficient ntawm thermal conductivity ntawm qhob nce ho. Thaum lub caij txias, ntes tau hauv qhov porescov khoom siv dej khov. Qhov tshwm sim yog tias cov cua kub tuav zoo ntawm cov phab ntsa, cov plag tsev thiab cov qab nthab tau txo qis ntxiv.

Qhov degree ntawm noo noo permeability ntawm ntau hom pob zeb yuav txawv. Raws li qhov ntsuas no, cov khoom raug faib ua ob peb qib.

Moisture permeability ntawm pob zeb

qib pob zeb	W4	W6	W8	W10-W14	W16-W20
Dej-cement ratio (tsis muaj ntxiv)	0, 6	0, 55	0, 45	0, 35	0, 30

Ntoo ua ib qho insulator

Ob leeg "txias" hnyav thiab lub teeb pob zeb, cov thermal conductivity uas tsawg, tau kawg, yog nrov heev thiab nrhiav-tom qab hom khoom siv hauv tsev. Txawm li cas los xij, lub hauv paus ntawm feem ntau cov tsev thiab cov qauv tsim los ntawm cov cement mortar tov nrog crushed pob zeb los yog pob zeb rubble.

Qhob sib tov lossis cov blocks ua los ntawm nws kuj yog siv rau kev tsim cov hnab ntawv hauv tsev. Tab sis feem ntau, lwm yam khoom siv los sib sau ua ke hauv pem teb, qab nthab thiab phab ntsa, piv txwv li, ntoo. Beam thiab board sib txawv, ntawm chav kawm, muaj zog tsawg dua li pob zeb. Txawm li cas los xij, qhov degree ntawm thermal conductivity ntawm ntoo, ntawm chav kawm, yog qis dua. Rau pob zeb, qhov ntsuas no, raws li peb pom, yog 0.12-1.74 W / (m ° C). Hauv tsob ntoo, thermal conductivity coefficient nyob ntawm, suav nrogsuav nrog thiab los ntawm cov tsiaj no.

Cov khoom siv hluav taws xob ntawm ntau hom ntoo

Nyob ntoo	Pine	Linden, fir	Spruce	Poplar, ntoo qhib, maple
Thermal conductivity W/(m°C)	0, 1	0, 15	0, 11	0, 17-0, 2

Nyob hauv lwm hom tsiaj, daim duab no yuav txawv. Nws ntseeg tau tias qhov nruab nrab thermal conductivity ntawm ntoo hla cov fibers yog 0.14 W / (m ° C). Txoj hauv kev zoo tshaj plaws los thaiv qhov chaw los ntawm qhov txias yog cedar. Nws thermal conductivity tsuas yog 0.095 W / (m C).

Cib ua ib qho insulator

Tom ntej, rau kev sib piv, xav txog cov yam ntxwv ntawm thermal conductivity thiab cov khoom siv hauv tsev nrov. Nyob rau hauv cov nqe lus ntawm lub zog zog, cib tsis tsuas yog tsis inferior rau pob zeb, tab sis feem ntau surpasses nws. Tib yam siv rau qhov ntom ntawm lub tsev pob zeb no. Tag nrho cov cib siv niaj hnub no hauv kev tsim vaj tsev thiab cov vaj tse tau muab faib ua ceramic thiab silicate.

Ob hom pob zeb no, dhau los, tuaj yeem yog:

• ncig;
• nrog voids;
• slotted.

Tau kawg, cov cib khoom khaws cov cua kub hnyav dua li qhov khoob thiab qhov khoob.

Thermal conductivity ntawm cib

Brick	puv lub cev silicate / ceramic	Silicate / ceramic nrog voids	YSlotted silicate/ceramic
Thermal conductivity W/(m°C)	0, 7-0, 8/0, 5-0, 8	0, 66 /0, 57	0, 4/0, 34-0, 43

Cov thermal conductivity ntawm pob zeb thiab cib yog li yuav luag tib yam. Ob leeg silicate thiab ceramic pob zeb insulate chav los ntawm qhov txias tsis muaj zog. Yog li ntawd, cov tsev tsim los ntawm cov khoom siv no yuav tsum tau insulated ntxiv. Raws li cov insulators thaum sheathing cib phab ntsa, nrog rau cov uas tau nchuav los ntawm cov pob zeb hnyav hnyav, nthuav polystyrene lossis cov ntaub plaub ntxhia feem ntau yog siv. Koj tseem tuaj yeem siv cov porous blocks rau lub hom phiaj no.

Yuav ua li cas thermal conductivity xam

qhov ntsuas no tau txiav txim siab rau cov khoom sib txawv, suav nrog pob zeb, raws li cov qauv tshwj xeeb. Nyob rau hauv tag nrho, ob txoj kev yuav siv tau. Lub thermal conductivity ntawm pob zeb yog txiav txim los ntawm tus qauv Kaufman. Nws zoo li no:

0.0935x(m) 0.5x2.28m + 0.025, qhov twg m yog qhov loj ntawm cov tshuaj.

Rau cov dej ntub dej (ntau tshaj 3%) cov kev daws teeb meem, cov qauv Nekrasov siv: (0.196 + 0.22 m2) 0.5 - 0.14.

nthuav pob zeb nrog qhov ntom ntawm 1000 kg / m3 muaj qhov hnyav ntawm 1 kg. Raws li, piv txwv li, raws li Kaufman, qhov no yuav tau txais ib coefficient ntawm 0.238. Lub thermal conductivity ntawm pob zeb yog txiav txim siab ntawm qhov sib tov kub ntawm +25 C. Rau cov khoom txias thiab rhuab, nwsCov duab yuav txawv me ntsis.