Experimental investigations on the thermal insulation performance of SiC opacifier doped silica aerogel at large temperature difference
Experimental investigations on the thermal insulation performance of SiC opacifier doped silica aerogel at large temperature difference
复制标题
SiC乳浊剂掺杂二氧化硅气凝胶大温差隔热性能实验研究
DOI：
10.1016/j.ijthermalsci.2020.106681
复制
发表时间：
2021-02-01
影响因子：
4.5
通讯作者：
Li Zeng-Yao
中科院分区：
文献类型：
--
作者：
Pang Hao-Qiang;Li Zeng-Yao
借鉴热流计法的经验，设计、建立并验证了大温差下SiC乳浊剂掺杂SiO2气凝胶隔热性能的实验系统。该实验系统的测试段为对称的双层结构，冷表面通过NESLAB ThermoFlex 2500恒温器循环水来保持温度恒定，热表面采用电加热。与传统的背表面温度响应方法相比，冷表面温度是定量可控的。基于现有的实验系统和方法，可以通过分析绝热体热表面在初始稳态、非稳态和最终新稳态的整个传热过程中的温度响应，定性和定量地评价绝热体的绝热性能。定性地，热表面温度越高，热表面温升越快，材料的隔热性能越好;定量地，基于半无限介质模型和傅立叶定律，得到材料的有效导热系数。结果表明，在小温差（400 K）下，体积分数为0%、1%和5.84%的3.5 μ m SiC遮光剂掺杂SiO2气凝胶的有效热导率分别为0.02559 W m（-1）K-1、0.02844 W m（-1）K-1和0.03305 W m（-1）K-1，体积分数为1%的3.5 μ m SiC颗粒掺杂的SiO2气凝胶的隔热性能足够好，而体积分数为5.84%的3.5 μ m SiC颗粒掺杂的SiO2气凝胶对阻挡热辐射的作用有限。
Drawn on the experience of the heat-flow-meter method, an experimental system is designed, established and validated to investigate the thermal insulation performance of SiC opacifier doped silica aerogel at large temperature difference. The test section of the experimental system is a symmetrical sandwich-structure, while the temperature of the cold surface keeps constant by circulating the water from the thermostat, NESLAB ThermoFlex2500, and the hot surface is electrically heated. Compared with the traditional method of the back-surface temperature response, the cold surface temperature is quantitatively controllable. Based on the present experimental system and method, the thermal insulation performance of insulator can be qualitatively and quantitatively evaluated by analyzing the temperature responses of the hot surface through the whole heat transfer process including the initial steady-state, the unsteady-state, and the final new steady-state. Qualitatively, the higher the temperature of the hot surface is and the faster the temperature rise of the hot surface is, the better the thermal insulation performance of the material has; quantitatively, the effective thermal conductivity of the materials is obtained based on the semi-infinite medium model and Fourier's Law. The present results show that the effective thermal conductivities of silica aerogel doped by 3.5 mu m SiC opacifier with different volume fraction of 0%, 1%, and 5.84% are about 0.02559 W m(-1) K-1, 0.02844 W m(-1) K-1, and 0.03305 W m(-1) K-1, respectively, at small temperature difference (400 K), the thermal insulation performance of silica aerogel doped by 3.5 mu m SiC particle with a volume fraction of 1% is good enough, though 3.5 mu m SiC particle with a volume fraction of 5.84% has a marginal improvement in blocking the thermal radiation within silica aerogel.