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Your search keyword '"Feng, Jinpeng"' showing total 6 results
Start Over Author "Feng, Jinpeng" Topic thermal insulation
6 results on '"Feng, Jinpeng"'

1. Thermal shrinkage inhibition mechanism of fumed silica based thermal insulating composite

Author

Youlan Wang, Su Xiujuan, Wang Guifang, Yang Jinlin, Wei Mo, Shaojian Ma, Lin Meiqun, and Feng Jinpeng

Subjects
Materials science, Nanoporous, business.industry, 020209 energy, Composite number, Energy Engineering and Power Technology, 02 engineering and technology, Molding (process), 021001 nanoscience & nanotechnology, Industrial and Manufacturing Engineering, Thermal conductivity, Thermal insulation, 0202 electrical engineering, electronic engineering, information engineering, Thermal stability, Composite material, 0210 nano-technology, business, Fumed silica, Shrinkage
Abstract

Fumed silica based thermal insulating composite is a novel nanoporous material with excellent thermal insulating performance. However, shrinkage at higher temperatures (>800 °C) is a great challenge in application. In this work, fumed silica based thermal insulating composite was prepared by a dry molding method and fumed alumina was introduced to improve high-temperature thermal stability of the composite. The result shows volume shrinkage can decrease from 18.49% to 2.61% at 1000 °C when 20 wt% fumed alumina is added as an inhibitor. Thermal shrinkage inhibition mechanism was investigated by molecular dynamics simulation. The models of fumed silica and fumed alumina super cells were built and mean square displacement (MSD) was calculated. The result indicates MSD of fumed silica is 0.198 A2 at 1000 °C while that of fumed alumina is only 0.0151 A2. In addition, thermal insulating property was comprehensively studied and the effect of fumed alumina on thermal conductivity was analyzed. The result shows this composite has excellent thermal insulating performance with thermal conductivity of 0.052 W/m·K at 800 °C and the introduction of fumed alumina has almost no effect on thermal insulating property. This work can provide theoretical guidelines for the choice of shrinkage inhibitor.

Published
2017

2. Heating temperature effect on the hygroscopicity of expanded vermiculite.

Author

Feng, Jinpeng, Liu, Meng, Mo, Wei, and Su, Xiujuan

Subjects
*VERMICULITE, *TEMPERATURE effect, *THERMAL insulation, *SURFACE area measurement, *INFRARED spectroscopy
Abstract

The hygroscopicity of expanded vermiculite is one of major influence factors for thermal insulating performance. To explore the water absorption properties of expanded vermiculite prepared via electrical heating method, heating temperature effect on the hygroscopicity of expanded vermiculite was investigated under various humidity circumstances. The influencing mechanisms were analyzed by means of Thermogravimetric Analysis-Differential Scanning Calorimeter technique (TG-DSC), Fourier-Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), and the Brunauer–Emmett–Teller technique (BET) for the measurement of the specific surface area. The results of water absorption experiments indicated that the hygroscopicity of vermiculite showed an inversely proportional relationship to heating temperature and the water absorption content of EV-900 was only 6.206 mg/g with a dramatic decline of 91.5% in comparison with that of RV. This decline of water absorption capacity was mainly attributed to the decrease of interlamellar spacing and specific surface area. In addition, environment humidity had a significant effect on water absorption capacity and velocity. The water absorption content of EV-400 sample increased dramatically from 48.414 mg/g at the humidity of 55%–72.929 mg/g at the humidity of 95%, and the equilibrium time reduced from 3 h to 0.5 h. This study will provide a new perspective and theoretical guidance for the development of vermiculite based thermal insulating materials. [ABSTRACT FROM AUTHOR]

Published
2021
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3. Radiative heat attenuation mechanisms for nanoporous thermal insulating composites

Author

Yang Jinlin, Xia Feng, Su Xiujuan, Youlan Wang, Lin Meiqun, Wei Mo, Feng Jinpeng, Qiang Huang, and Ma Shaojian

Subjects
Materials science, business.industry, 020209 energy, Energy Engineering and Power Technology, 02 engineering and technology, 021001 nanoscience & nanotechnology, Thermal conduction, Industrial and Manufacturing Engineering, Thermal transmittance, Thermal conductivity measurement, Thermal conductivity, Thermal radiation, Thermal insulation, Heat transfer, 0202 electrical engineering, electronic engineering, information engineering, Composite material, 0210 nano-technology, Absorption (electromagnetic radiation), business
Abstract

Nanoporous thermal insulating composites of fumed silica, opacifier, and fiber have been prepared by a dry molding method. SiC is adopted as an opacifier to improve thermal insulating performance at higher temperatures where radiation heat transfer plays an important role in entire heat transfer system. Radiative heat attenuation mechanisms have been illuminated by calculating thermal radiation optical parameters including scattering, absorption, and attenuation factors. The result shows fumed silica has low attenuation factor in infrared wavelength range, only 0.00188 for infrared radiation with a wavelength of 3.14 μm. The introduction of SiC can remarkably restrain radiative heat transfer, and the maximum attenuation factor reaches up to 5.848 for infrared radiation with a wavelength of 8.646 μm. The effect of SiC particle size on thermal radiation optical parameters is also studied. The choice of SiC particle size should match up with serving temperature of this insulation. In addition, thermal conductivity measurement has been employed to verify the accuracy of calculation results. Thermal conductivity can significantly decrease from 0.119 to 0.041 W/(m K) at 773 K when 25 wt% SiC (0.877 μm) is added into the composites.

Published
2016

4. Micro-nano scale heat transfer mechanisms for fumed silica based thermal insulating composite

Author

Feng Jinpeng, Wei Mo, Su Xiujuan, Yang Jinlin, Shaojian Ma, and Meng Liu

Subjects
Materials science, business.industry, 020209 energy, General Chemical Engineering, Composite number, 02 engineering and technology, Condensed Matter Physics, 01 natural sciences, Atomic and Molecular Physics, and Optics, 010406 physical chemistry, 0104 chemical sciences, Thermal conductivity, Thermal radiation, Thermal insulation, Heat transfer, Thermal, 0202 electrical engineering, electronic engineering, information engineering, Radiative transfer, Composite material, business, Fumed silica
Abstract

Developing nanoporous thermal insulation materials is an effective method for solving energy consumption problems. In this study, fumed silica based thermal insulating composite was prepared using a novel dry molding method. Thermal conductivity was measured using a guarded hot plate method in the steady state. The results indicated that this composite exhibited excellent thermal insulating performance, achieving an ultra-low thermal conductivity of 0.0205 W/mK at 100 °C. By analyzing the microstructure using field emission scanning electron microscopy (FESEM), we found that the fiber surface was modified by a 12 μm-thick layer of fumed silica particles that reduced solid heat transfer. However, at high temperatures, thermal insulating performance decreased rapidly, and thermal conductivity reached up to 0.119 W/mK at 500 °C. Based on this problem, a heat transfer model was constructed to explain micro-nano scale heat transfer mechanisms of this composite. The results indicated that gas-solid coupled thermal conductivity occupied a large proportion of 78.3% at 100 °C, but the value was only 0.015 W/mK. As the serving temperature increased, radiative heat transfer gradually occupied the dominant position in total heat transfer. Radiative thermal conductivity reached up to 0.101 W/mK at 500 °C, which was approximately 93.3% of total thermal conductivity. Therefore, it was apparent that the increase in radiative heat transfer was the main cause of the decline in thermal insulating performance at high temperatures. Additionally, the effect of the fiber mass ratio on thermal conductivity was investigated at various temperatures. Empirical and simulated data were compared, and the results revealed that the heat transfer model was basically consistent with experimental findings, achieving a mean error of only 4.78%.

Published
2020

5. Hydrothermal synthesis of a novel expanded vermiculite/xonotlite composite for thermal insulation.

Author

Wang, Xiaoben, Feng, Jinpeng, Hwang, Jiann-Yang, Dai, Tianya, Liu, Shuhan, Wu, Zhenjiang, Mo, Wei, and Su, Xiujuan

Subjects
*THERMAL insulation, *VERMICULITE, *INDUSTRIAL energy consumption, *FIELD emission electron microscopy, *HYDROTHERMAL synthesis, *THERMOGRAPHY, *THERMAL conductivity
Abstract

[Display omitted] • A novel expanded vermiculite/xonotlite insulation composite was prepared via the hydrothermal method. • Vermiculite thermal expansion and nano xonotlite fiber synthesis were comprehensively studied. • The effect of intercalation on thermal insulating performance was systematically investigated. Natural disasters caused by global warming are threatening the survival of mankind. Reducing carbon emissions is an effective way to prevent global warming. In recent years, the construction industry is playing a dominant role in global energy consumption. Aimed to solve the problem of high energy consumption in the construction industry, a novel expanded vermiculite/xonotlite thermal insulation composite was successfully prepared via the hydrothermal method. The microstructure and thermal performance of the composite were systematically analyzed using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), laser flash analysis (LFA), and infrared thermal imaging. The test results indicated that xonotlite fibers could be inserted well into the interlayers of expanded vermiculite. And the intercalation of xonotlite greatly improved the thermal insulation performance of expanded vermiculite at high temperature. The thermal conductivity of this composite decreased with intercalation rate increasing. The composite with intercalation rate of 51.43 % had the lowest thermal conductivity of 0.2116 W/mK at 800 °C which was 55.36 % lower than the expanded vermiculite sample. Meanwhile, this composite had good thermal stability and high temperature resistance. In addition, the thermal expansion of vermiculite and the synthesis of nano-xonotlite fibers were comprehensively studied and discussed. This study will provide a new perspective and ideas for developing vermiculite-based thermal insulating materials. [ABSTRACT FROM AUTHOR]

Published
2023
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6. Study of thermal stability of fumed silica based thermal insulating composites at high temperatures

Author

Feng, Jinpeng, Yan, Yongye, Chen, Deping, Ni, Wen, Yang, Jinlin, Ma, Shaojian, and Mo, Wei

Subjects
*SILICA fume, *THERMAL insulation, *COMPOSITE materials, *HIGH temperatures, *ELECTRON microscopy, *MICROSTRUCTURE, *THERMOPHYSICAL properties
Abstract

Abstract: This work investigated thermal stability of fumed silica based thermal insulating composites prepared by dry molding technology. The results showed that the composites could keep excellent thermal stability at the temperatures below 800°C. However, when the samples were used at higher temperatures (>800°C), the volume shrinkage increased sharply, which directly led to a serious deformation and then affected thermal insulating properties in applications. The utilization of fumed alumina could significantly improve thermal stability of the composites. When 5wt.% fumed alumina was added, the volume shrinkage decreased from 10.49% to 3.47% at 1000°C. The desirable results would be achieved by adjusting the amount of fumed alumina according to practical using temperature. In addition, field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) were employed to characterize the microstructure and phase transformations of the composites treated at different temperatures. [Copyright &y& Elsevier]

Published
2011
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