玻璃传热系数k值

1、新版玻璃传热系数k值玻璃传热系数K值幕墙中空玻璃传热系数计算方法如下：1.公式Pr=c/入式中动态黏度，取1.761X10-5kg/(m?s);c比热容,空气取1.008xi03J/(kg?K)、氧气取0.519xi03J/(kg?K);导热系数，空气取2.496X10-2W/(m?K)、氧气取1.684X10-2W/(m?K)。Gr=9.81s3ATp2/Tmc2式中s中空玻璃的气层厚度(m);AT外片玻璃表面温差，取15K;密度,空气取1.232kg/m3、氮气取1.669kg/m3;Tm玻璃的平均温度，取283K;动态黏度，空气取1.761x10-5kg/(m?s)、氧气取2.164X1

2、0-5kg/(m?s)。Nu=0.035(GrPr)0.38，如计算结果Nu,1，取Nu=1。Hg=Nu入/sW/(m2?K)HT=4(1/e1+1/e2-1)-1XTm3式中常数，取5.67X10-8W/(m2?K4);e1外片玻璃表面的校正辐射率；&2内片玻璃表面的校正辐射率；e1、£2取值:普通透明玻璃刀v,15%0.837(GB/T2680表4)真空磁控溅射镀膜玻璃刀V?15%0.45(GB/T2680表4)4v,15%0.70(GB/T2680表4)LOW-E镀膜玻璃4v,15%应由试验取得，如无试验资料时可取0.090.115。hs=hg+hT1/ht=1/hs+

3、5/ri式中两片玻璃总厚度；r1玻璃热阻，取1(m?K)/W。1/U=1/he+1/hi+1/ht式中he玻璃外表面换热系数，取23(19)W/(m2?K);hi玻璃内表面换热系数，取8(8.7)W/(m2?K)。括号中数字为GB50176t关规定。2.例题例1求12mms玻+12mm气)+12mm白玻中空玻璃的传热系数。解Pr=c/人=1.761X10-5X1.008X103/2.496X10-2=0.711Gr=9.81s3ATp2/Tmi2=9.81X0.0123X15X1.2322/283乂(1.761X10-5)2=4398Nu0.035(GrPr)0.38=0.035(0.711乂

4、4398)0.38=0.745取Nu=1Hg=Nu入/s=1X2.496X10-2/0.012=2.08W/(m2?K)hT=4工(1/e1+1/e2-1)-1XTm3=4X5.67X10-8X(1/0.837+1/0.837-1)-1 X 2833=3.7 W/(m2?K)hs=hg+hT=2.08+3.7=5.78W/(m2?K)1/ht=1/hs+5/r1=1/5.78+0.024/1=0.197(m2?K)/W1/U=1/he+1/hi+1/ht=1/8+1/23+0.197=0.365m2?K)/WU=1/0.365=2.74W/(m2?K)例2求12mmfe反射(刀v,15%

5、63;1=0.70)+12mm(空气)+12mm白玻中空玻璃的传热系数。解Pr=c/人=1.761X10-5X1.008X103/2.496X10-2=0.711Gr=9.81s3ATp2/Tmi2=9.81X0.0123X15X1.2322/283X(1.761X10-5)2=4398Nu0.035(GrPr)0.38=0.035(0.711乂4398)0.38=0.745取Nu=1Hg=Nu入/s=1X2.496X10-2/0.012=2.08W/(m2?K)HT=4(1/e1+g2-1)-1XTm3=4X5.67X10-8X(1/0.70+1/0.837-1)-1X2833=3.17W/

6、(m2?K)hs=hg+hT=2.08+3.17=5.25W/(m2?K)1/ht=1/hs+6A1=1/5.25+0.024/1=0.2.14(m2?K)/W1/U=1/he+1/hi+1/ht=1/8+1/23+0.214=0.382m2?K)/WU=1/0.382=2.62W/(m2?K)例3求12mms玻+12mm笈气)+12mmLOW-M空玻璃的传热系数。解Pr=c/人=1.761X10-5X1.008X103/2.496X10-2=0.711Gr=9.81s3ATp2/Tmi2=9.81X0.0123X15X1.2322/283X(1.761X10-5)2=4398Nu0.035(

7、GrPr)0.38=0.035(0.711乂4398)0.38=0.745取Nu=1Hg=Nu入/s=1X2.496X10-2/0.012=2.08W/(m2?K)HT=<(1/e1+1/e2-1)-1XTm3=4X5.67X10-8X(1/0.837+1/0.10-1)12833=0.504W/(m2?K)hs=hg+hT=2.08+0.504=2.584W/(m2?K)1/ht=1/hs+6/r1=1/2.584+0.024/1=0.411(m2?K)/W1/U=1/he+1/hi+1/ht=1/8+1/23+0.411=0.579m2?K)/WU=1/0.579=1.73W/(m2

8、?K)例4求12mms玻+12mm融气)+12mm白玻中空玻璃的传热系数。解Pr=c/人=2.164X10-5X0.519X103/1.684X10-2=0.6669Gr=9.81s3ATp2/Trni2=9.81X0.0123X15X1.6992/283X(2.164乂10-5)2=5538Nu0.035(GrPr)0.38=0.035(0.6669X5538)0.38=0.794取Nu=1hg=Nu入/s=1X1.684X10-2/0.012=1.4W/(m2?K)hT=4工(1/e1+1/e2-1)-1XTm3=4X5.67X10-8X(1/0.837+1/0.837-1)12833=3

9、.7W/(m2?K)hs=hg+hT=1.4+3.7=5.10W/(m2?K)1/ht=1/hs+6/r1=1/5.10+0.024/1=0.22(m2?K)/W1/U=1/he+1/hi+1/ht=1/8+1/23+0.22=0.388m2?K)/W例5求12mmS玻+12mm(K气)+12mmLOW-M空玻璃的传热系数。解Pr=c/X=2.164X10-5X0.519X103/1.684X10-2=0.6669Gr=9.81s3ATp2/Trni2=9.81X0.0123X15X1.6992/283X(2.164X10-5)2=5538Nu0.035(GrPr)0.38=0.035(0.6669X5538)0.38=0.794取Nu=1hg=Nu入/s=1X1.684X10-2/0.012=1.4W/(m2?K)hT=4(1/e1+1/e2-1)-1XTm3=4X5.67X10-8X(1/0.837+1/0.10-1)1X2833=0.504W/(