The plastic anisotropy of sheet metal is usually caused by preferred orientation of grains, developed by mechanical deformation and thermal treatment. In the present study, a Taylor-like polycrystal model suggested by...The plastic anisotropy of sheet metal is usually caused by preferred orientation of grains, developed by mechanical deformation and thermal treatment. In the present study, a Taylor-like polycrystal model suggested by Asaro and Needleman is applied to investigate the evolution of the anisotropic behavior of a face centered cubic (FCC) polycrystalline metal, which is considered having {111} 110 slip systems, by stretching it along an arbitrary direction after it has undergone a plane-strain compression that rationally simulates the cold rolling process of FCC polycrystalline pure aluminium. By using the Taylor-like polycrystal model, pole fgures are obtained to describe the texture development of polycrystalline aggregate after plane-strain compression, and then the plastic anisotropy of polycrystalline aggregate is evaluated by stretch- ing the polycrystalline aggregate in different direction in term of yield stress. According to the results, the contours of longitudinal fow stress in three-dimensional orientation space are given and analyzed. Experiment results similar to the prediction of planar anisotropy can be found in the literature written by Takahashi et al. that indirectly show the correctness of the prediction of non-planar plastic anisotropy by this analysis.展开更多
Aromatics,as essential basic chemical raw materials,are widely used in rubber,nylon,resins,solvents,and other products.Light aromatics such as benzene,toluene,and xylene serve as cornerstones of modern chemical indust...Aromatics,as essential basic chemical raw materials,are widely used in rubber,nylon,resins,solvents,and other products.Light aromatics such as benzene,toluene,and xylene serve as cornerstones of modern chemical industries.Conventional aromatic production predominantly relies on petroleum resources.Compared with traditional petroleum-derived aromatic production processes,syngas to aromatics technology offer signifi cant advantages in terms of energy consumption,environmental emissions,and production costs.Notably,coal-based syngas to aromatics technology offers several advantages,including a shorter process flow,lower hydrogen-to-carbon ratio requirements,and improved pressure compatibility with existing systems.Therefore,syngas to aromatics technology is poised to play an increasingly vital role in future energy transitions,driving the evolution of green,low-carbon chemical industries.One of the key challenges in the technology of synthesizing aromatics from coal-based syngas lies in the construction of the catalytic system.Another challenge lies in the design of the reactor equipment.Based on the above key challenges,this review systematically summarizes three major catalytic mechanisms:the modified Fischer-Tropsch synthesis pathway,the methanol-mediated pathway,and the formaldehyde-mediated pathway,deeply analyses the factors influencing the catalytic performance in the syngas to aromatics process,discusses the role of reactor design in this process;on this basis,it further explores the potential and prospects of coal-based syngas to aromatics technology in promoting the development of green and low-carbon chemical industry.展开更多
An experimental investigation on the flow characteristics and the local heat and mass transfer between coarse wet particles and hot gas in the circulating fluidized bed (CFB) has been performed. A two-thermocouple con...An experimental investigation on the flow characteristics and the local heat and mass transfer between coarse wet particles and hot gas in the circulating fluidized bed (CFB) has been performed. A two-thermocouple contrast method was developed to measure the local gas and solid temperature along the height of the bed. The influences of air superficial velocity, solid rate and initial moisture content on the local heat and mass transfer between gas and solid were examined. The correlations of heat and mass transfer coefficients between gas and coarse wet particles in CFB were obtained.展开更多
基金Project supported by the National Natural Science Foundation of China(No.50371070),the Aviation Science Foun-dation of China(No.01C53015)and the Doctoral Foundation of Northwestern Polytechnical University.
文摘The plastic anisotropy of sheet metal is usually caused by preferred orientation of grains, developed by mechanical deformation and thermal treatment. In the present study, a Taylor-like polycrystal model suggested by Asaro and Needleman is applied to investigate the evolution of the anisotropic behavior of a face centered cubic (FCC) polycrystalline metal, which is considered having {111} 110 slip systems, by stretching it along an arbitrary direction after it has undergone a plane-strain compression that rationally simulates the cold rolling process of FCC polycrystalline pure aluminium. By using the Taylor-like polycrystal model, pole fgures are obtained to describe the texture development of polycrystalline aggregate after plane-strain compression, and then the plastic anisotropy of polycrystalline aggregate is evaluated by stretch- ing the polycrystalline aggregate in different direction in term of yield stress. According to the results, the contours of longitudinal fow stress in three-dimensional orientation space are given and analyzed. Experiment results similar to the prediction of planar anisotropy can be found in the literature written by Takahashi et al. that indirectly show the correctness of the prediction of non-planar plastic anisotropy by this analysis.
文摘Aromatics,as essential basic chemical raw materials,are widely used in rubber,nylon,resins,solvents,and other products.Light aromatics such as benzene,toluene,and xylene serve as cornerstones of modern chemical industries.Conventional aromatic production predominantly relies on petroleum resources.Compared with traditional petroleum-derived aromatic production processes,syngas to aromatics technology offer signifi cant advantages in terms of energy consumption,environmental emissions,and production costs.Notably,coal-based syngas to aromatics technology offers several advantages,including a shorter process flow,lower hydrogen-to-carbon ratio requirements,and improved pressure compatibility with existing systems.Therefore,syngas to aromatics technology is poised to play an increasingly vital role in future energy transitions,driving the evolution of green,low-carbon chemical industries.One of the key challenges in the technology of synthesizing aromatics from coal-based syngas lies in the construction of the catalytic system.Another challenge lies in the design of the reactor equipment.Based on the above key challenges,this review systematically summarizes three major catalytic mechanisms:the modified Fischer-Tropsch synthesis pathway,the methanol-mediated pathway,and the formaldehyde-mediated pathway,deeply analyses the factors influencing the catalytic performance in the syngas to aromatics process,discusses the role of reactor design in this process;on this basis,it further explores the potential and prospects of coal-based syngas to aromatics technology in promoting the development of green and low-carbon chemical industry.
文摘An experimental investigation on the flow characteristics and the local heat and mass transfer between coarse wet particles and hot gas in the circulating fluidized bed (CFB) has been performed. A two-thermocouple contrast method was developed to measure the local gas and solid temperature along the height of the bed. The influences of air superficial velocity, solid rate and initial moisture content on the local heat and mass transfer between gas and solid were examined. The correlations of heat and mass transfer coefficients between gas and coarse wet particles in CFB were obtained.
