The Experts below are selected from a list of 4038 Experts worldwide ranked by ideXlab platform
Tom Morén - One of the best experts on this subject based on the ideXlab platform.
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Colour responses from wood, thermally modified in superheated Steam and Pressurized Steam atmospheres
Wood Material Science and Engineering, 2010Co-Authors: Ola Dagbro, Petteri Torniainen, Olov Karlsson, Tom MorénAbstract:Abstract In this study, two different methods were used to produce thermally modified wood. One was carried out in a typical kiln drying chamber using superheated Steam (SS) and the other used Pressurized Steam in an autoclave cylinder (PS). Overall, both processes followed the same principles and the wood was not treated with any chemicals. Two wood species were studied, Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). Treatments in the autoclave were carried out under pressure using temperatures of 160°C, 170°C and 180°C. Temperatures of 190°C and 212°C were used in treatments in the chamber at normal air pressure. The colour was measured using L*C*H colour space. Results for both species showed that similar L* (lightness) can be reached at lower (20–30°C) temperatures using PS compared with SS treatment. The hue angle of PS-treated wood was smaller than that of SS-treated wood. No significant difference in C* (chroma) was detected. The difference in E value between PS- and SS-treated wood...
Yitian Fang - One of the best experts on this subject based on the ideXlab platform.
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Catalytic Steam gasification of sawdust char on K-based composite catalyst at high pressure and low temperature
Chemical Engineering Science, 2019Co-Authors: Weihong Jiao, Zhiqing Wang, Xing Zhou, Yangang Mei, Rongtao Feng, Tao Liu, Liang Ding, Jiejie Huang, Yitian FangAbstract:Abstract The effects of temperature, pressure, Steam ratio and K-based composite catalysts on the Pressurized Steam gasification of sawdust char were studied and the physicochemical structure of composite catalysts was characterized in detail. The results indicated that Steam promoted the production of hydrogen but suppressed that of CH4. The generation of CH4 required high pressure, low temperature and suitable Steam atmosphere. The composite catalysts reduced the reaction temperature and increased the carbon conversion, theirs catalytic performance ranked in descending order was KCe > KCo > KFe > KNi, where KCe showed perfect catalytic performance, which mainly determined by the ability to activate carbon during Pressurized Steam gasification of char. KFe and KCo were more conducive to water-gas-shift reaction, while KNi had the better performance on gasification reaction. The transformation paths of the composite catalysts were as follows: Ce(NO3)3·6H2O → CeO2, Co(NO3)2·6H2O → CoO/Co3O4 → Co → CoO, Fe(NO3)3·9H2O → Fe2O3 → FeO → Fe3O4 and Ni(NO3)2·6H2O → NiO → Ni.
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Investigation into the kinetics of Pressurized Steam gasification of chars with different coal ranks
Journal of Thermal Analysis and Calorimetry, 2013Co-Authors: Jiejie Huang, Jiantao Zhao, Chunyu Li, Yitian FangAbstract:The Steam gasification of coal chars derived from three different ranks of typical Chinese coals was studied in a Pressurized fixed-bed differential reactor at elevated pressure (up to 2.0 MPa). Three mathematical models [volumetric model (VM), grain model (GM), and random pore model (RPM)] for the gasification kinetics of different chars were validated, through which the kinetic parameters were obtained and discussed. The results show that the evolution trend of the coal char gasification rate with carbon conversion differs from coal ranks and has little change with pressure and temperature. The Pressurized gasification process of the Shenmu sub-bituminous coal char (SM char) and the Jingcheng anthracite char (JC char) can be well-predicted by the RPM, while that of the Huolinhe lignite char can be better described by the VM. The pressure has little effect on the options of the reaction kinetic models for the three chars. The kinetic parameter E is almost a constant independent of pressure, while k0 changes with pressure, and it seems that k0 would be almost a constant over 1.0 MPa for SM and JC chars. The reaction order decreases with increasing the total system pressure and differs from different coal types.
Ding Tao - One of the best experts on this subject based on the ideXlab platform.
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Effects of heat treatment on the moisture adsorption characteristic and dimensional stability of wood
Journal of Nanjing Forestry University, 2015Co-Authors: Ding Tao, Gu Lianbai, Cai JiabinAbstract:Heat treatment of Pinus sylvestris and Quercus mongolica boards were carried out in atmospheric stream or0. 45 MPa Pressurized Steam. Hygroscopicity and dimensional stability of the treated wood were compared with the control. The results showed that heat treatments not only lowered the equilibrium moisture contents(EMC) of the wood,but also altered the pattern of its moisture adsorption in high humidity environment. When the environmental relative humidity increased from 69% to 94%,the EMC change rates of the heat treated samples were just one third of those of the control samples. This might be attributed to the reconstruction of wood cell wall during the heat treatments. Dimensional stability of heat treated samples was significantly improved as a result. The radial and tangential swelling of PressurizedSteam treated Pinus sylvestris samples decreased by 34% and 47% compared to those of the control ones. For Quercus mongolica samples,the corresponding values were 46% and 51%. Most tangential anti-swelling efficiency(ASE) values of the heat treated samples were higher than their radial ASE values. That means swelling difference between radial direction and tangential direction was also reduced after heat treatments. It was also showed that Pressurized Steam induces more pronounced property modification than atmospheric Steam.
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Study on Biological Durability of Pressurized Steam-treated Wood
China Forest Products Industry, 2010Co-Authors: Ding Tao, Zhu KunAbstract:Samples of Mongolian Pine and Mongolian Oak were high-temperature heat treated in atmospheric Steam and Pressurized Steam respectively.The differences of biological durability between two kinds of heat treated samples and untreated ones were compared.The results revealed that high-temperature heat treatment,especially heat treatment with Pressurized Steam,could substantially improve the durability class of wood from class 4(non-durable,such as untreated samples) to class 1 (very durable,such as treated Mongolian Pine) and class 2(durable,such as treated Mongolian Oak). Heat treatment could prevent wood from attacking by blue stain,but was useless for resisting mold attack.Wood surface coating with oily paint was an effective way for avoiding mold attack.
Guangping Han - One of the best experts on this subject based on the ideXlab platform.
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High temperature and Pressurized Steaming/silane coupling co-modification for wood fibers and its effect on the properties of wood fiber/HDPE composites
Macromolecular Research, 2017Co-Authors: Xun Gao, Wanli Cheng, Guangping Han, Lihui XuanAbstract:Poplar fibers were pretreated under high temperature and Pressurized Steam at different temperatures and pressures; they were further modified using different amounts of silane coupling agent. The obtained modified fibers were used to prepare wood fiber/high-density polyethylene (HDPE) composites by an extrusion-molding process. The effects of high temperature and Pressurized Steaming/silane coupling co-modification on the properties of wood fiber/HDPE composites were investigated. The results show that after the high temperature and Pressurized Steaming treatment, the amount of hydroxyl groups on the surface of the fibers and surface polarity of the fibers decreased, whereas the crystallinity and thermal stability significantly increased. The storage modulus and mechanical properties of the composites improved as well. The addition of silane to the Steam-treated fibers further enhanced the storage modulus, loss modulus, and the mechanical properties of the composites. Moreover, when the wood fibers were only modified by adding silane and the silane content was 5%, the prepared composites showed better mechanical properties than the high temperature and Pressurized Steaming treatment. However, the addition of a small amount of silane to the wood fibers exposed to Steam at 170 °C and 0.8 MPa provided even better results; when 2% silane was added, the composites showed the best mechanical properties.
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Optimization of High Temperature and Pressurized Steam Modified Wood Fibers for High-Density Polyethylene Matrix Composites Using the Orthogonal Design Method.
Materials (Basel Switzerland), 2016Co-Authors: Xun Gao, Wanli Cheng, Guangping Han, Lihui XuanAbstract:The orthogonal design method was used to determine the optimum conditions for modifying poplar fibers through a high temperature and Pressurized Steam treatment for the subsequent preparation of wood fiber/high-density polyethylene (HDPE) composites. The extreme difference, variance, and significance analyses were performed to reveal the effect of the modification parameters on the mechanical properties of the prepared composites, and they yielded consistent results. The main findings indicated that the modification temperature most strongly affected the mechanical properties of the prepared composites, followed by the Steam pressure. A temperature of 170 °C, a Steam pressure of 0.8 MPa, and a processing time of 20 min were determined as the optimum parameters for fiber modification. Compared to the composites prepared from untreated fibers, the tensile, flexural, and impact strength of the composites prepared from modified fibers increased by 20.17%, 18.5%, and 19.3%, respectively. The effect on the properties of the composites was also investigated by scanning electron microscopy and dynamic mechanical analysis. When the temperature, Steam pressure, and processing time reached the highest values, the composites exhibited the best mechanical properties, which were also well in agreement with the results of the extreme difference, variance, and significance analyses. Moreover, the crystallinity and thermal stability of the fibers and the storage modulus of the prepared composites improved; however, the hollocellulose content and the pH of the wood fibers decreased.
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Wood Modification at High Temperature and Pressurized Steam: a Relational Model of Mechanical Properties Based on a Neural Network
BioResources, 2015Co-Authors: Hong Yang, Wanli Cheng, Guangping HanAbstract:Thermally modified wood has high dimensional stability and biological durability.But if the process parameters of thermal modification are not appropriate, then there will be a decline in the physical properties of wood.A neural network algorithm was employed in this study to establish the relationship between the process parameters of high-temperature and high-pressure thermal modification and the mechanical properties of the wood. Three important parameters: temperature, relative humidity, and treatment time, were considered as the inputs to the neural network. Back propagation (BP) neural network and radial basis function (RBF) neural network models for prediction were built and compared. The comparison showed that the RBF neural network model had advantages in network structure, convergence speed, and generalization capacity. On this basis, the inverse model, reflecting the relationship between the process parameters and the mechanical properties of wood, was established. Given the desired mechanical properties of the wood, the thermal modification process parameters could be inversely optimized and predicted. The results indicated that the model has good learning ability and generalization capacity. This is of great importance for the theoretical and applicational studies of the thermal modification of wood.
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Effect of Pressurized Steam treatment on selected properties of wheat straws
Industrial Crops and Products, 2009Co-Authors: Guangping Han, Wanli Cheng, James Deng, Chunping Dai, S. Y. ZhangAbstract:Abstract Wheat straw fibers were modified via a Pressurized Steam treatment. The effect of Steam pressure (i.e., 0.2, 0.4, 0.6, 1.0 MPa) and treatment time (i.e., 5 and 10 min) on chemical composition, sorption isotherm, thermal and mechanical properties of the treated fibers was investigated. Differential scanning calorimetry analysis showed that thermal characteristics of the treated straw samples were shifted indicating the improved thermal stability. The ash and extractive content of the treated straw was reduced; and the materials were likely removed when the Steam was released. The removal of ash and extractives could improve the wettability of wheat straw when it is used in combination with polymer matrices. Sorption behavior study showed that Steam treatment reduced the hydrophilic characteristic of wheat straw. Tensile strength of the treated straw was significantly enhanced. The tensile strength of straw after treatment at a Steam pressure of 1.0 MPa for 5 min was more than twice higher than that of the control group. The study demonstrated that Pressurized Steam treatment is an effective pre-treatment process for wheat straw fibers as possible reinforcement element in polymer matrices.
Ola Dagbro - One of the best experts on this subject based on the ideXlab platform.
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Colour responses from wood, thermally modified in superheated Steam and Pressurized Steam atmospheres
Wood Material Science and Engineering, 2010Co-Authors: Ola Dagbro, Petteri Torniainen, Olov Karlsson, Tom MorénAbstract:Abstract In this study, two different methods were used to produce thermally modified wood. One was carried out in a typical kiln drying chamber using superheated Steam (SS) and the other used Pressurized Steam in an autoclave cylinder (PS). Overall, both processes followed the same principles and the wood was not treated with any chemicals. Two wood species were studied, Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). Treatments in the autoclave were carried out under pressure using temperatures of 160°C, 170°C and 180°C. Temperatures of 190°C and 212°C were used in treatments in the chamber at normal air pressure. The colour was measured using L*C*H colour space. Results for both species showed that similar L* (lightness) can be reached at lower (20–30°C) temperatures using PS compared with SS treatment. The hue angle of PS-treated wood was smaller than that of SS-treated wood. No significant difference in C* (chroma) was detected. The difference in E value between PS- and SS-treated wood...