The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Jianfeng Wu - One of the best experts on this subject based on the ideXlab platform.
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Preparation of Cordierite-mullite Ceramics for Solar Thermal Storage
Journal of Wuhan University of Technology-materials Science Edition, 2019Co-Authors: Jianfeng Wu, Chenglong Lu, Xiaohong Xu, Yinfeng ZhangAbstract:We developed cordierite-mullite composite ceramic materials to package and encapsulate PCM, and presented a preparation process from raw materials of kaolin, talc and alumina. The properties and microstructre of cordierite-mullite composite ceramic were studied. Due to the strengthening effects of mullite, the sample C2 (80 wt% of cordierite and 20 wt % of mullite) sintered at 1 420 °C possessed excellent physical properties. Determined by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analysis, cuboid-shaped cordierite crystals and needle-like or long quadrilateral-prism mullite crystals with staggered patterns were found, which endowed the composites preferable mechanical strength. After 30 cycles of Thermal shock (room temperature to about 1 100 °C, air-cooled), the sample presented superior Thermal shock resistance, which is suitable to be applied as Solar Thermal Storage materials.
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In situ synthesis and mechanism of mullite-silicon carbide composite ceramics for Solar Thermal Storage
Ceramics International, 2018Co-Authors: Hao Cheng, Jianfeng Wu, Fen Ye, Senglin Leng, Sizhan WuAbstract:Abstract SiC combined with mullite ceramic, which is an important Thermal Storage material in Solar Thermal power generation systems, was synthesized in situ by semidry pressing and carbon-buried sintering of mixtures containing andalusite, calcined bauxite, kaolin, talc and SiC. The effects of the SiC addition and sintering temperature on the physical properties, crystal phases, microstructure, Thermal shock resistance, thermo-physical properties and oxidation resistance of the specimens were studied. The results indicate that the formula W-1 (SiC content: 20%) sintered at 1540 °C has the best performance, yielding a bending strength of 36.46 MPa, the completion of 30 cycles of the Thermal shock test without cracking and an increase in the bending strength by 136.86%. The silicon carbide on the surface of the specimen is oxidized to produce a dense SiO 2 protective film, which effectively prevents the oxygen from incorporating into the interior of specimen and further oxidation. Potentially, the mullite-silicon carbide composite ceramics could be applicable as materials for Solar Thermal Storage devices.
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High-temperature alloy/honeycomb ceramic composite materials for Solar Thermal Storage applications: Preparation and stability evaluation
Ceramics International, 2017Co-Authors: Xiaohong Xu, Jianfeng Wu, Xiaoyang XuAbstract:Abstract SiC w /Al 2 O 3 honeycomb ceramics were engaged as sensible shell materials for encapsulating Al-Si alloys (latent heat materials) in the honeycomb holes to obtain alloy/ceramic composite materials with a high Thermal Storage capacity for high-temperature Solar Thermal Storage applications. The stability evaluation between the sensible honeycomb ceramics and the latent alloys had been conducted and the failure mechanism for the latent alloys was investigated. Results indicated that the addition of the latent alloys could improve the Thermal Storage capacity of the sensible honeycomb ceramics significantly by >114% and the Thermal Storage densities of honeycombs containing Al-12Si and Al-20Si alloys were 1141.3 kJ/kg and 1106 kJ/kg (400–900 °C), respectively. The composite materials exhibited excellent physical and chemical stability. No cracks formed in the honeycomb ceramics and no leakage of alloys was discovered after the composite materials were exposed to 100 Thermal cycles in a high-temperature testing environment. The oxidation of Al at >600 °C would lower the latent heat of alloys and the Thermal Storage densities decreased to 1039.9 kJ/kg and 1013.2 kJ/kg after enduring 100 Thermal cycles. This study not only provides a sensible-latent system of Thermal Storage materials with excellent stability but also gives an insight into the protection of metal containers against the corrosion from Al-based alloys.
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Effect of silicon on properties of Al2O3-SiCw composite ceramics in-situ synthesized by aluminium-assisted carboThermal reduction of coal series kaolin for Solar Thermal Storage
Journal of Alloys and Compounds, 2017Co-Authors: Xiaohong Xu, Jianfeng Wu, Xiaoyang Xu, Yaxiang Zhang, Kun LiAbstract:Abstract For further improving the yield of SiC whiskers (SiCw), the heat capacity and the Thermal conductivity of Al2O3-SiCw composite ceramics in-situ synthesized by aluminium-assisted carboThermal reduction of coal series kaolin (CSK) for Solar Thermal Storage, silicon (Si) was added to consume the silica residual in CSK and formulae of series CA with 0.8–8 wt% Si additive were designed on the basis of the previous formula (CSK 68 wt%, Al 32 wt%). Effects of Si additive on the yield of SiCw as well as the morphology and the properties of Al2O3-SiCw composites were investigated in detail. Results indicated that Si additive was superior in terms of improving the SiCw yield and the properties of the composites. Samples CA3 (with 5.6 wt% Si additive) fired at 1600–1650 °C achieved the highest relative content of SiCw as 21.4–21.6%, which was much higher than that of the basic formula with increasing rates of 44.6–45.9%. The added Si was also highly in favor of densifying the composites and samples CA3 fired at 1600 °C obtained the optimal properties: 2.45 g cm−3 for bulk density, 63.5 MPa for bending strength, 7.38 × 10−6 °C−1 for coefficient of Thermal expansion, 9.36 W (m K)−1 for Thermal conductivity (room temperature), 0.85 J (g K)−1 for heat capacity (room temperature). The great effect of Si additive on the consumption of silica and the improvement of SiC yield could increase the heat capacity and the Thermal conductivity of the composites effectively.
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in situ synthesis of a cordierite andalusite composite for Solar Thermal Storage
Solar Energy Materials and Solar Cells, 2013Co-Authors: Jianfeng Wu, Xiaohong Xu, Guanghui Leng, Kun Li, Cheng ZhouAbstract:Abstract An innovative Thermal Storage material, in-situ synthesised cordierite combined andalusite (Al 2 O 3 ·SiO 2 ), was prepared via semi-dry pressing followed by pressureless sintering. The samples were mainly composed of andalusite (the main raw material), with in-situ synthesised cordierite added to improve the Thermal shock resistance. The results indicate that the formula L4 (70% andalusite, 13% talcum, 13% kaolin and 4% γ-Al 2 O 3 ) sintered at 1400 °C has the best Thermal stock resistance, physical properties and chemical properties. The L4 sample can withstand 30 Thermal shock test cycles without cracking (wind cooling from 1100 °C to 25 °C), and the bending strength after the Thermal shock cycle test increased 26.20% rather than decreasing. Other properties are as follows: apparent porosity: 22.95%; water absorption: 10.71%; bulk density: 2.14 g/cm 3 ; bending strength: 92.74 MPa; coefficient of Thermal expansion: 4.11×10 −6 /°C; specific heat capacity: 0.95 kJ·(kg K) −1 ; Thermal conductivity coefficient: 0.58×10 −2 cm 2 s −1 ; and Thermal conductivity: 1.17 W·(m K) −1 . The examination of the phase composition indicates that cordierite, mullite, sillimanite, cristobalite and α-quartz are the main phase elements. Analysis of the microstructure shows that the cordierite crystals were formed during the sintering process and were dispersed evenly in the mullite crystals, which gave the samples a favourable Thermal shock resistance. It was concluded that the ceramic material, a combination of cordierite and andalusite, is an excellent candidate for Solar Thermal Storage material due to its high Thermal shock resistance, temperature resistance and strength.
H. S. Udaykumar - One of the best experts on this subject based on the ideXlab platform.
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Transient multi-day simulations of Thermal Storage and heat extraction for a finned Solar Thermal Storage device
Solar Energy, 2017Co-Authors: Mike Augspurger, H. S. UdaykumarAbstract:The effect of combining metal fins (Al) for heat spreading and recovery with phase change material (a mixture of NaNO3and KNO3) on the performance of a Thermal Storage device is investigated. High-resolution transient simulations are performed covering two days of Solar energy influx and heat extraction. The solver uses the enthalpy method to track melting, a strongly coupled implicit scheme to calculate conjugate heat transfer, and a dynamically refined mesh to ease grid creation and maximize computational efficiency. A potential application is Thermal Storage for Solar cooking, although other applications can also be envisaged. The energy inputs of the simulations are based average Solar radiation during a 48 h Solar cycle in New Delhi, India in June with a 1.5 m2Solar reflector. Four different fin designs for an insulated latent heat Thermal Storage device (TSD) to be used with a Solar cooker are tested. The four designs are compared based on their ability to spread heat evenly and rapidly into the phase change material (PCM) and the ease with which heat can be withdrawn from the device for cooking. The tests demonstrate the potential for using long term, multiday numerical simulations in the evaluation of TSD designs.
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a cartesian grid solver for simulation of a phase change material pcm Solar Thermal Storage device
Numerical Heat Transfer Part B-fundamentals, 2016Co-Authors: Mike Augspurger, H. S. UdaykumarAbstract:ABSTRACTA Cartesian grid solver is developed that is capable of simulating the convection-dominated melting processes in a latent-heat Thermal Storage device (TSD). The Navier-Stokes equations are solved using a dynamically refined mesh. The phase boundary is tracked using the enthalpy method. Conjugate heat transfer is calculated with a strongly coupled implicit scheme. The approach does not require the creation of a geometry-specific grid, and so allows for efficient prototyping of different complex geometric designs. Systematic benchmarking of the results against other numerical approaches is conducted, followed by tests of two basic prototypes for the design of a TSD.
Cheng Zhou - One of the best experts on this subject based on the ideXlab platform.
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in situ synthesis of a cordierite andalusite composite for Solar Thermal Storage
Solar Energy Materials and Solar Cells, 2013Co-Authors: Jianfeng Wu, Xiaohong Xu, Guanghui Leng, Kun Li, Cheng ZhouAbstract:Abstract An innovative Thermal Storage material, in-situ synthesised cordierite combined andalusite (Al 2 O 3 ·SiO 2 ), was prepared via semi-dry pressing followed by pressureless sintering. The samples were mainly composed of andalusite (the main raw material), with in-situ synthesised cordierite added to improve the Thermal shock resistance. The results indicate that the formula L4 (70% andalusite, 13% talcum, 13% kaolin and 4% γ-Al 2 O 3 ) sintered at 1400 °C has the best Thermal stock resistance, physical properties and chemical properties. The L4 sample can withstand 30 Thermal shock test cycles without cracking (wind cooling from 1100 °C to 25 °C), and the bending strength after the Thermal shock cycle test increased 26.20% rather than decreasing. Other properties are as follows: apparent porosity: 22.95%; water absorption: 10.71%; bulk density: 2.14 g/cm 3 ; bending strength: 92.74 MPa; coefficient of Thermal expansion: 4.11×10 −6 /°C; specific heat capacity: 0.95 kJ·(kg K) −1 ; Thermal conductivity coefficient: 0.58×10 −2 cm 2 s −1 ; and Thermal conductivity: 1.17 W·(m K) −1 . The examination of the phase composition indicates that cordierite, mullite, sillimanite, cristobalite and α-quartz are the main phase elements. Analysis of the microstructure shows that the cordierite crystals were formed during the sintering process and were dispersed evenly in the mullite crystals, which gave the samples a favourable Thermal shock resistance. It was concluded that the ceramic material, a combination of cordierite and andalusite, is an excellent candidate for Solar Thermal Storage material due to its high Thermal shock resistance, temperature resistance and strength.
Xiaohong Xu - One of the best experts on this subject based on the ideXlab platform.
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Preparation of Cordierite-mullite Ceramics for Solar Thermal Storage
Journal of Wuhan University of Technology-materials Science Edition, 2019Co-Authors: Jianfeng Wu, Chenglong Lu, Xiaohong Xu, Yinfeng ZhangAbstract:We developed cordierite-mullite composite ceramic materials to package and encapsulate PCM, and presented a preparation process from raw materials of kaolin, talc and alumina. The properties and microstructre of cordierite-mullite composite ceramic were studied. Due to the strengthening effects of mullite, the sample C2 (80 wt% of cordierite and 20 wt % of mullite) sintered at 1 420 °C possessed excellent physical properties. Determined by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analysis, cuboid-shaped cordierite crystals and needle-like or long quadrilateral-prism mullite crystals with staggered patterns were found, which endowed the composites preferable mechanical strength. After 30 cycles of Thermal shock (room temperature to about 1 100 °C, air-cooled), the sample presented superior Thermal shock resistance, which is suitable to be applied as Solar Thermal Storage materials.
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High-temperature alloy/honeycomb ceramic composite materials for Solar Thermal Storage applications: Preparation and stability evaluation
Ceramics International, 2017Co-Authors: Xiaohong Xu, Jianfeng Wu, Xiaoyang XuAbstract:Abstract SiC w /Al 2 O 3 honeycomb ceramics were engaged as sensible shell materials for encapsulating Al-Si alloys (latent heat materials) in the honeycomb holes to obtain alloy/ceramic composite materials with a high Thermal Storage capacity for high-temperature Solar Thermal Storage applications. The stability evaluation between the sensible honeycomb ceramics and the latent alloys had been conducted and the failure mechanism for the latent alloys was investigated. Results indicated that the addition of the latent alloys could improve the Thermal Storage capacity of the sensible honeycomb ceramics significantly by >114% and the Thermal Storage densities of honeycombs containing Al-12Si and Al-20Si alloys were 1141.3 kJ/kg and 1106 kJ/kg (400–900 °C), respectively. The composite materials exhibited excellent physical and chemical stability. No cracks formed in the honeycomb ceramics and no leakage of alloys was discovered after the composite materials were exposed to 100 Thermal cycles in a high-temperature testing environment. The oxidation of Al at >600 °C would lower the latent heat of alloys and the Thermal Storage densities decreased to 1039.9 kJ/kg and 1013.2 kJ/kg after enduring 100 Thermal cycles. This study not only provides a sensible-latent system of Thermal Storage materials with excellent stability but also gives an insight into the protection of metal containers against the corrosion from Al-based alloys.
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Effect of silicon on properties of Al2O3-SiCw composite ceramics in-situ synthesized by aluminium-assisted carboThermal reduction of coal series kaolin for Solar Thermal Storage
Journal of Alloys and Compounds, 2017Co-Authors: Xiaohong Xu, Jianfeng Wu, Xiaoyang Xu, Yaxiang Zhang, Kun LiAbstract:Abstract For further improving the yield of SiC whiskers (SiCw), the heat capacity and the Thermal conductivity of Al2O3-SiCw composite ceramics in-situ synthesized by aluminium-assisted carboThermal reduction of coal series kaolin (CSK) for Solar Thermal Storage, silicon (Si) was added to consume the silica residual in CSK and formulae of series CA with 0.8–8 wt% Si additive were designed on the basis of the previous formula (CSK 68 wt%, Al 32 wt%). Effects of Si additive on the yield of SiCw as well as the morphology and the properties of Al2O3-SiCw composites were investigated in detail. Results indicated that Si additive was superior in terms of improving the SiCw yield and the properties of the composites. Samples CA3 (with 5.6 wt% Si additive) fired at 1600–1650 °C achieved the highest relative content of SiCw as 21.4–21.6%, which was much higher than that of the basic formula with increasing rates of 44.6–45.9%. The added Si was also highly in favor of densifying the composites and samples CA3 fired at 1600 °C obtained the optimal properties: 2.45 g cm−3 for bulk density, 63.5 MPa for bending strength, 7.38 × 10−6 °C−1 for coefficient of Thermal expansion, 9.36 W (m K)−1 for Thermal conductivity (room temperature), 0.85 J (g K)−1 for heat capacity (room temperature). The great effect of Si additive on the consumption of silica and the improvement of SiC yield could increase the heat capacity and the Thermal conductivity of the composites effectively.
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in situ synthesis of a cordierite andalusite composite for Solar Thermal Storage
Solar Energy Materials and Solar Cells, 2013Co-Authors: Jianfeng Wu, Xiaohong Xu, Guanghui Leng, Kun Li, Cheng ZhouAbstract:Abstract An innovative Thermal Storage material, in-situ synthesised cordierite combined andalusite (Al 2 O 3 ·SiO 2 ), was prepared via semi-dry pressing followed by pressureless sintering. The samples were mainly composed of andalusite (the main raw material), with in-situ synthesised cordierite added to improve the Thermal shock resistance. The results indicate that the formula L4 (70% andalusite, 13% talcum, 13% kaolin and 4% γ-Al 2 O 3 ) sintered at 1400 °C has the best Thermal stock resistance, physical properties and chemical properties. The L4 sample can withstand 30 Thermal shock test cycles without cracking (wind cooling from 1100 °C to 25 °C), and the bending strength after the Thermal shock cycle test increased 26.20% rather than decreasing. Other properties are as follows: apparent porosity: 22.95%; water absorption: 10.71%; bulk density: 2.14 g/cm 3 ; bending strength: 92.74 MPa; coefficient of Thermal expansion: 4.11×10 −6 /°C; specific heat capacity: 0.95 kJ·(kg K) −1 ; Thermal conductivity coefficient: 0.58×10 −2 cm 2 s −1 ; and Thermal conductivity: 1.17 W·(m K) −1 . The examination of the phase composition indicates that cordierite, mullite, sillimanite, cristobalite and α-quartz are the main phase elements. Analysis of the microstructure shows that the cordierite crystals were formed during the sintering process and were dispersed evenly in the mullite crystals, which gave the samples a favourable Thermal shock resistance. It was concluded that the ceramic material, a combination of cordierite and andalusite, is an excellent candidate for Solar Thermal Storage material due to its high Thermal shock resistance, temperature resistance and strength.
Kun Li - One of the best experts on this subject based on the ideXlab platform.
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Effect of silicon on properties of Al2O3-SiCw composite ceramics in-situ synthesized by aluminium-assisted carboThermal reduction of coal series kaolin for Solar Thermal Storage
Journal of Alloys and Compounds, 2017Co-Authors: Xiaohong Xu, Jianfeng Wu, Xiaoyang Xu, Yaxiang Zhang, Kun LiAbstract:Abstract For further improving the yield of SiC whiskers (SiCw), the heat capacity and the Thermal conductivity of Al2O3-SiCw composite ceramics in-situ synthesized by aluminium-assisted carboThermal reduction of coal series kaolin (CSK) for Solar Thermal Storage, silicon (Si) was added to consume the silica residual in CSK and formulae of series CA with 0.8–8 wt% Si additive were designed on the basis of the previous formula (CSK 68 wt%, Al 32 wt%). Effects of Si additive on the yield of SiCw as well as the morphology and the properties of Al2O3-SiCw composites were investigated in detail. Results indicated that Si additive was superior in terms of improving the SiCw yield and the properties of the composites. Samples CA3 (with 5.6 wt% Si additive) fired at 1600–1650 °C achieved the highest relative content of SiCw as 21.4–21.6%, which was much higher than that of the basic formula with increasing rates of 44.6–45.9%. The added Si was also highly in favor of densifying the composites and samples CA3 fired at 1600 °C obtained the optimal properties: 2.45 g cm−3 for bulk density, 63.5 MPa for bending strength, 7.38 × 10−6 °C−1 for coefficient of Thermal expansion, 9.36 W (m K)−1 for Thermal conductivity (room temperature), 0.85 J (g K)−1 for heat capacity (room temperature). The great effect of Si additive on the consumption of silica and the improvement of SiC yield could increase the heat capacity and the Thermal conductivity of the composites effectively.
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in situ synthesis of a cordierite andalusite composite for Solar Thermal Storage
Solar Energy Materials and Solar Cells, 2013Co-Authors: Jianfeng Wu, Xiaohong Xu, Guanghui Leng, Kun Li, Cheng ZhouAbstract:Abstract An innovative Thermal Storage material, in-situ synthesised cordierite combined andalusite (Al 2 O 3 ·SiO 2 ), was prepared via semi-dry pressing followed by pressureless sintering. The samples were mainly composed of andalusite (the main raw material), with in-situ synthesised cordierite added to improve the Thermal shock resistance. The results indicate that the formula L4 (70% andalusite, 13% talcum, 13% kaolin and 4% γ-Al 2 O 3 ) sintered at 1400 °C has the best Thermal stock resistance, physical properties and chemical properties. The L4 sample can withstand 30 Thermal shock test cycles without cracking (wind cooling from 1100 °C to 25 °C), and the bending strength after the Thermal shock cycle test increased 26.20% rather than decreasing. Other properties are as follows: apparent porosity: 22.95%; water absorption: 10.71%; bulk density: 2.14 g/cm 3 ; bending strength: 92.74 MPa; coefficient of Thermal expansion: 4.11×10 −6 /°C; specific heat capacity: 0.95 kJ·(kg K) −1 ; Thermal conductivity coefficient: 0.58×10 −2 cm 2 s −1 ; and Thermal conductivity: 1.17 W·(m K) −1 . The examination of the phase composition indicates that cordierite, mullite, sillimanite, cristobalite and α-quartz are the main phase elements. Analysis of the microstructure shows that the cordierite crystals were formed during the sintering process and were dispersed evenly in the mullite crystals, which gave the samples a favourable Thermal shock resistance. It was concluded that the ceramic material, a combination of cordierite and andalusite, is an excellent candidate for Solar Thermal Storage material due to its high Thermal shock resistance, temperature resistance and strength.