管道保溫層厚度的計(jì)算方法(三種方法)

管道保溫層厚度的計(jì)算方法(三種方法),,,,

(一).透過控制保溫層外表面溫度的方法計(jì)算,,,,備注

管道內(nèi)介質(zhì)的溫度℃,t=,95,輸入,

主保溫層外表面溫度℃,tw1=,34.66,,tw1=33.4+0.028×(t－50)(或者根據(jù)工藝要求直接輸入)

保溫層平均溫度℃,tp=,64.83,,tp=(t+tw1)/2

保溫材料在tp溫度下的導(dǎo)熱系數(shù)W/m?℃,λ1=,0.048,輸入,

管道外徑m,dw=,0.219,輸入,

管道周遭空氣溫度,tk=,28,輸入,

管道外的風(fēng)速m/s,ω=,4,輸入,

保溫層表面到周遭空氣的放熱系數(shù)W/(m2?k),αh=,25.53,,αh=11.63+6.95×ω0.5

設(shè)管道主保溫層外徑為d1:,d1/dw×ln(d1/dw)=,0.1556,,d1/dw×ln(d1/dw)=2×λ1×(t-tw1)/[αh×dw×(tw1-tk)]

令d1/dw×ln(d1/dw)=x?lnx查表得︰,x?lnx=,0.1556,輸入,見後面附表1

,x=,1.147,輸入,見後面附表1

則保溫層厚度δ為:m,δ=,0.0161,,δ=(d1-dw)/2=(x-1)×dw/2

(二).透過控制最大熱損失的方法計(jì)算,,,,

管道內(nèi)介質(zhì)的溫度℃,t=,95,輸入,

保溫層平均溫度℃,tp=,70,輸入,"此計(jì)算方法計(jì)算保溫層濃度時(shí),外表面溫度未知,平均溫度查附表2"

保溫材料的導(dǎo)熱系數(shù)W/m?℃,λ1=,0.048,輸入,

管道外徑m,dw=,0.219,輸入,

管道周遭空氣溫度,tk=,28,輸入,

保溫層表面到周遭空氣的放熱系數(shù)W/(m2?k),αh=,0.034,,查附表3

單位表面允許最大散熱量q,q=,93,,查附表4

設(shè)管道主保溫層外徑為d1:,d1=,0.3527,,ln(d1/dw)=2×3.14×λ1×[(t-tk)/q－αh]

則保溫層厚度δ為:m,δ=,0.0668,,

"注:當(dāng)預(yù)先定出管道或設(shè)備的表面最大允許散熱損失時(shí),其保溫層的經(jīng)濟(jì)厚度為:",δ1=,0.0037,,δ1=2.69×dw1.2×λ11.35×tw11.73/q1.5

(三).透過控制溫度降時(shí)的保溫層厚度計(jì)算,,,,

管道內(nèi)的介質(zhì)流量kg/h,G=,35,輸入,

介質(zhì)平均比熱kj/(kg?℃),C=,896,輸入,

介質(zhì)始端溫度℃,t1=,95,輸入,

介質(zhì)終端溫度℃,t2=,70,輸入,

管道輸送長度m,L=,1000,輸入,

平面保溫層到周遭空氣的放熱系數(shù)W/(m2?k),αh?1=,0.344,輸入,"室內(nèi)取0.086,室外取0.344"

管道支吊架局部保溫系數(shù),K1=,1.2,輸入,"吊架室內(nèi)1.10,室外1.15;支架室內(nèi)1.15,室外1.20"

當(dāng)(t1-tk)/(t2-tk)<2時(shí),,TRUE,,"當(dāng)(t1-tk)/(t2-tk)<2時(shí),用下面公式計(jì)算︰"

設(shè)管道主保溫層外徑為d1:,d1=,0.2290,,ln(d1/dw)=2×3.14×λ1×[(tp-tk)×L×K1/[G×C×(t1-t2)－αh?1]

則保溫層厚度δ為:m,δ=,0.0050,,δ=(d1-dw)/2

當(dāng)(t1-tk)/(t2-tk)≧2時(shí),,FALSE,,當(dāng)(t1-tk)/(t2-tk)≧2時(shí)，用下面公式計(jì)算︰

設(shè)管道主保溫層外徑為d1:,d1=,0.2227,,ln(d1/dw)=2×3.14×λ1×[(t2-tk)×L×K1/[G×C×(t1-tk)－αh?1]

則保溫層厚度δ為:m,δ=,0.0018,,δ=(d1-dw)/2

(四).直埋管道的保溫層厚度計(jì)算,,,,

土壤的導(dǎo)熱系數(shù)W/m?℃,λt=,1.74,,一般可取1.74W/m?℃

土壤層溫度℃,tt=,5,,一般可取5℃

埋管深度m,h=,1.2,,

設(shè)管道主保溫層外徑為d1:,d1=,0.0442,,lnd1=[λ1×(tw1-tt