核壳结构遮光剂对SiO_2气凝胶辐射传热的影响
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摘要
纯SiO_2气凝胶在波长小于8μm范围内几乎透明,加入一定量的遮光剂可以有效抑制辐射传热从而提高气凝胶的高温隔热性能。本文根据分层Mie散射理论和扩散近似理论,研究了不同种类核壳结构的遮光剂如SiO_2、SiC、炭黑(Carbon)空心球结构和Carbon/SiO_2和Carbon/SiC双层球结构的遮光特性和遮光剂掺杂气凝胶的辐射热导率,研究表明:空心结构遮光剂在对遮光性能影响不大的情况下,可以极大的降低遮光剂-气凝胶复合材料的密度;Carbon/SiC遮光剂的遮光性能与纯炭黑相当,可应用于高温隔热材料中。本研究对新型遮光剂的设计以及气凝胶复合材料性能的优化具有重要的指导意义。
Pure silica aerogels are nearly transparent to the electromagnetic wave at wavelength below 8 μm. Doping opacifiers into silica aerogels can reduce the infrared radiative transfer and improve the insulation performance at high temperature. In this work, the extinction performance of different kind of core/shell opacifiers, including hollow spheres and core/shell opacifiers with core of carbon black, and the radiaive thermal conductivity of opacifiers-loaded silica aerogels are invsetigated based on the coated Mie-theory and Rossland diffusion approximation. The results show that the hollow opacifiers could greatly reduce the densities of the opacifier-loaded silica aerogels without deteriorating appreciably their insulating capability. The carbon/SiC opacifier exhibits excllent extinction performance as homogeneous solid carbon opacifier, which should be a promising opacifier for silica aerogels at high temperature. The results of this paper present important references for the process design and improvement of comprehensive performance of opacifier-loaded silica aerogels.
Pure silica aerogels are nearly transparent to the electromagnetic wave at wavelength below 8 μm. Doping opacifiers into silica aerogels can reduce the infrared radiative transfer and improve the insulation performance at high temperature. In this work, the extinction performance of different kind of core/shell opacifiers, including hollow spheres and core/shell opacifiers with core of carbon black, and the radiaive thermal conductivity of opacifiers-loaded silica aerogels are invsetigated based on the coated Mie-theory and Rossland diffusion approximation. The results show that the hollow opacifiers could greatly reduce the densities of the opacifier-loaded silica aerogels without deteriorating appreciably their insulating capability. The carbon/SiC opacifier exhibits excllent extinction performance as homogeneous solid carbon opacifier, which should be a promising opacifier for silica aerogels at high temperature. The results of this paper present important references for the process design and improvement of comprehensive performance of opacifier-loaded silica aerogels.
引文
[1] Hribesh L W. Aerogel Applications[J]. Journal of NonCrystalline Solids, 1998, 225:335-342
[2] Baetens R, Jelle B P, Gustavsen A. Aerogel Insulation for Building Applications:a State-of-the-art Review[J].Energy and Buildings, 2011, 43(4):761-769
[3] Aegerter M A, Leventis N, Koebel M M. Aerogels Handbook[M]. Springer Science&Business Media, 2011
[4]何飞,郝晓东,李垚.气凝胶热特性的研究现状[J].材料导报,2005, 19(12):20-22He F, Hao X D, Li Y. Study on Thermal Properties of Aerogels[J]. Materials Reviews, 2005, 19(12):20-22
[5]封金鹏,陈德平,杨淑勤,等.SiC作为纳米SiO_2多孔绝热材料红外遮光剂的式验研究[J].宇航材料工艺,2009, 39(1):38-40Feng J P, Chen D P, Yang S Q, et al. Nano Silica Porous Thermal Insulating Material With SiC as Infrare Opaci-fier[J]. Aerospace Materials&Technology, 2009, 39(1):38-40
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[7] Singh H, Geisler M, Menzel F. Experimental Investigations Into Thermal Transport Phenomena in Vacuum Insulation Panels(VIPs)Using Fumed Silica Cores[J]. Energy and Buildings, 2015, 107(1):76-83
[8]于海童,刘东,段远源,等.气凝胶中遮光剂的辐射特性计算及优化设计[J].宇航材料工艺,2014, 44(1):47-52Yu H T, Liu D, Duan Y Y, et al. Radiative Properties Calculation and Optimization of Opacifier Particles in Aerogel[J]. Aerospace Materials&Technology, 2014, 44(1):47-52
[9] Zhao J J, Duan Y Y, Wang X D, et al. Optical and Radiative Properties of Infrared Opacifier Particles Loaded in Silica Aerogels for High Temperature Thermal Insulation[J], International Journal of Thermal Sciences, 2013,70(8):54-64
[10] Fang W Z, Zhang H, Chen L, et al. Numerical Predictions of Thermal Conductivities for the Silica Aerogel and Its Composites[J]. Applied Thermal Engineering, 2017, 115:1277-1286
[11] Tang G H, Zhao Y, Guo J F. Multi-layer Graded Doping in Silica Aerogel Insulation With Temperature Gradient[J]. International Journal of Heat and Mass Transfer, 2016,99:192-200
[12] M(a|¨)tzler C. MATLAB Functions for Mie Scattering and Absorption[R]. Germany:Institute of Applied Physics,University of Bern, 2002:1139-1151
[13] Wang X D, Sun D, Duan Y Y, et al. Radiative Characteristics of Opacifier-Loaded Silica Aerogel Composites[J]. Journal of Non-Crystalline Solids, 2013, 375(3):31-39
[14]刘晓东,戴景民.Mie散射理论测量粒子系复折射系数的透射方法[J].红外与激光工程,2009, 38(5):820-824Liu X D, Dai J M. Measurement of the Complex Refractive Index of Particles Based on Mie Theory and Transmission Method[J]. Infrared and Laser Engineering, 2009,38(5):820-824
[15] Zeng S Q, Hunt A, Greif R. Theoretical Modeling of Carbon Content to Minimize Heat Transfer in Silica Aerogel[J]. Journal of Non-Crystalline Solids, 1995, 186(2):271-277
[16] Wei G, Liu Y, Zhang X, et al. Thermal Conductivities Study on Silica Aerogel and Its Composite Insulation Materials[J]. International Journal of Heat&Mass Transfer,2011, 54(11/12):2355-2366
[17] Modest M F. Radiative Heat Transfer[M]. 2~(nd)Edtion.San Diego:Academic Press, 2003:361-375
[18] Pegourie B. Optical Properties of Alpha Silicon Carbide[J]. Astronomy&Astrophysics, 1988, 194:335-339
[19]方文振,张虎,屈肖迪,等.遮光剂对气凝胶复合材料隔热性能的影响[J].化工学报,2014, 65(S1):168-174Fang W Z, Zhang H, Qu X D, et al. Influence of Opacifiers on Thermal Insulation Properties of Composite Aerogels[J]. Journal of Chemical Industry and Engineering, 2014,65(S1):168-174
[2] Baetens R, Jelle B P, Gustavsen A. Aerogel Insulation for Building Applications:a State-of-the-art Review[J].Energy and Buildings, 2011, 43(4):761-769
[3] Aegerter M A, Leventis N, Koebel M M. Aerogels Handbook[M]. Springer Science&Business Media, 2011
[4]何飞,郝晓东,李垚.气凝胶热特性的研究现状[J].材料导报,2005, 19(12):20-22He F, Hao X D, Li Y. Study on Thermal Properties of Aerogels[J]. Materials Reviews, 2005, 19(12):20-22
[5]封金鹏,陈德平,杨淑勤,等.SiC作为纳米SiO_2多孔绝热材料红外遮光剂的式验研究[J].宇航材料工艺,2009, 39(1):38-40Feng J P, Chen D P, Yang S Q, et al. Nano Silica Porous Thermal Insulating Material With SiC as Infrare Opaci-fier[J]. Aerospace Materials&Technology, 2009, 39(1):38-40
[6] Wang J. Monolithic Silica Aerogel Insulation Doped with TiO_2 Powder and Ceramic Fibers[J]. Journal of NonCrystalline Solids, 1995, 186(1):296-300
[7] Singh H, Geisler M, Menzel F. Experimental Investigations Into Thermal Transport Phenomena in Vacuum Insulation Panels(VIPs)Using Fumed Silica Cores[J]. Energy and Buildings, 2015, 107(1):76-83
[8]于海童,刘东,段远源,等.气凝胶中遮光剂的辐射特性计算及优化设计[J].宇航材料工艺,2014, 44(1):47-52Yu H T, Liu D, Duan Y Y, et al. Radiative Properties Calculation and Optimization of Opacifier Particles in Aerogel[J]. Aerospace Materials&Technology, 2014, 44(1):47-52
[9] Zhao J J, Duan Y Y, Wang X D, et al. Optical and Radiative Properties of Infrared Opacifier Particles Loaded in Silica Aerogels for High Temperature Thermal Insulation[J], International Journal of Thermal Sciences, 2013,70(8):54-64
[10] Fang W Z, Zhang H, Chen L, et al. Numerical Predictions of Thermal Conductivities for the Silica Aerogel and Its Composites[J]. Applied Thermal Engineering, 2017, 115:1277-1286
[11] Tang G H, Zhao Y, Guo J F. Multi-layer Graded Doping in Silica Aerogel Insulation With Temperature Gradient[J]. International Journal of Heat and Mass Transfer, 2016,99:192-200
[12] M(a|¨)tzler C. MATLAB Functions for Mie Scattering and Absorption[R]. Germany:Institute of Applied Physics,University of Bern, 2002:1139-1151
[13] Wang X D, Sun D, Duan Y Y, et al. Radiative Characteristics of Opacifier-Loaded Silica Aerogel Composites[J]. Journal of Non-Crystalline Solids, 2013, 375(3):31-39
[14]刘晓东,戴景民.Mie散射理论测量粒子系复折射系数的透射方法[J].红外与激光工程,2009, 38(5):820-824Liu X D, Dai J M. Measurement of the Complex Refractive Index of Particles Based on Mie Theory and Transmission Method[J]. Infrared and Laser Engineering, 2009,38(5):820-824
[15] Zeng S Q, Hunt A, Greif R. Theoretical Modeling of Carbon Content to Minimize Heat Transfer in Silica Aerogel[J]. Journal of Non-Crystalline Solids, 1995, 186(2):271-277
[16] Wei G, Liu Y, Zhang X, et al. Thermal Conductivities Study on Silica Aerogel and Its Composite Insulation Materials[J]. International Journal of Heat&Mass Transfer,2011, 54(11/12):2355-2366
[17] Modest M F. Radiative Heat Transfer[M]. 2~(nd)Edtion.San Diego:Academic Press, 2003:361-375
[18] Pegourie B. Optical Properties of Alpha Silicon Carbide[J]. Astronomy&Astrophysics, 1988, 194:335-339
[19]方文振,张虎,屈肖迪,等.遮光剂对气凝胶复合材料隔热性能的影响[J].化工学报,2014, 65(S1):168-174Fang W Z, Zhang H, Qu X D, et al. Influence of Opacifiers on Thermal Insulation Properties of Composite Aerogels[J]. Journal of Chemical Industry and Engineering, 2014,65(S1):168-174