摘要
探讨二氧化硅气凝胶基体材料(未添加玻璃纤维、陶瓷纤维等用以改善二氧化硅气凝胶基体材料力学性能的功能添加物)等效热导率的数学模型,在不同结构尺度下(分别取0. 2、0. 4、0. 6、0. 8),分析环境压力(变化范围为1 Pa～100 kPa)、表观密度(变化范围为20～300 kg/m^3)、比表面积(变化范围为200～1 000 m^2/g)对二氧化硅气凝胶基体材料(以下简称基体材料)等效热导率的影响,基体材料自身热力学温度取300 K。环境压力、表观密度、比表面积一定条件下,基体材料等效热导率随结构尺度的减小而降低。结构尺度一定的条件下:环境压力为1 Pa～1 k Pa时,基体材料等效热导率基本不随环境压力的变化而变化;当环境压力大于1 kPa后,基体材料等效热导率随环境压力的增大迅速增大。基体材料等效热导率随着表观密度的增大先减小后增大,存在最佳表观密度,使基体材料等效热导率最小。基体材料等效热导率随着比表面积的增大而减小。
The mathematical model of equivalent thermal conductivity of silica aerogel matrix material（ not adding glass fiber or ceramic fiber function additives to improve the mechanical properties of silica aerogel matrix material） is discussed. The influences of environmental pressure（ variation range is 1 Pa to100 kPa）,apparent density（ variation range is 20 to300 kg/m^3） and specific surface area（ variation range is 200 to 1 000 m^2/g） on the equivalent thermal conductivity of silica aerogel matrix material（ hereinafter referred to as matrix material） are analyzed under different structural scales（ 0. 2,0. 4,0. 6 and 0. 8）. The thermodynamic temperature of the matrix material is300 K. Under certain conditions of environmental pressure,apparent density and specific surface area,the equivalent thermal conductivity of the matrix material decreases with the decrease of the structure scale. Under certain condition of the structural scale,the equivalent thermal conductivity of the matrix material does not change with the change of the environmental pressure when the environmental pressure is 1 Pa to1 kPa,and the equivalent thermal conductivity of the matrix material increases rapidly with the increase of the environmental pressure when the environmental pressure is greater than 1 kPa. The equivalent thermal conductivity of the matrix material decreases first and then increases with the increase of the apparent density,and there is the best apparent density,which makes the equivalent thermal conductivity of the matrix material minimum. The equivalent thermal conductivity of the matrix material decreases with the increase of the specific surface area.
作者
喻凡
赵湉湉
刘云苹
孙宇飞
YU Fan;ZHAO Tiantian;LIU Yunping;SUN Yufei
出处
《煤气与热力》
2018年第11期19-24,共6页
Gas & Heat
关键词
二氧化硅气凝胶
基体材料
热导率
影响因素
silica aerogel
matrix material
themlal conductivity
influencing factor
