In this paper, the distributions of particle velocity in a gas–solid fluidized bed with branched pipe distributor or circle distributor were measured by using a laser Doppler velocimetry. Our results show that, withi...In this paper, the distributions of particle velocity in a gas–solid fluidized bed with branched pipe distributor or circle distributor were measured by using a laser Doppler velocimetry. Our results show that, within a certain range of superficial gas velocity, when using circle distributor, the particle velocity is large and the distribution of the particle velocity is even more compared with the branched pipe distributor. On the basis of the amplitude of tangential movement statistics, the amplitude of tangential movement statistics(AVATMS) decreases with increasing the axial height under the appropriate superficial gas velocity.展开更多
Tin nanoparticles with different size distribution were synthesized using chemical reduction method by applying NaBH4 as reduction agent.The Sn nanoparticles smaller than 100 nm were less agglomerated and no obviously...Tin nanoparticles with different size distribution were synthesized using chemical reduction method by applying NaBH4 as reduction agent.The Sn nanoparticles smaller than 100 nm were less agglomerated and no obviously oxidized.The melting properties of these synthesized nanoparticles were studied by differential scanning calorimetry.The melting temperatures of Sn nanoparticles in diameter of 81,40,36 and 34 nm were 226.1,221.8,221.1 and 219.5？欲espectively.The size-dependent melting temperature and size-dependent latent heat of fusion have been observed.The size-dependent melting properties of tin nanoparticles in this study were also comparatively analyzed by employing different size-dependent theoretical melting models and the differences between these models were discussed.The results show that the experimental data are in accordance with the LSM model and SPI model,and the LSM model gives the better understanding for the melting property of the Sn nanoparticles.展开更多
Based on the ideal solution approximation, the model for size-dependent melting temperature of pure metal nanoparticles is extended to binary alloy systems. The developed model, free of any adjustable parameter, demon...Based on the ideal solution approximation, the model for size-dependent melting temperature of pure metal nanoparticles is extended to binary alloy systems. The developed model, free of any adjustable parameter, demonstrates that the melting temperature is related to the size and composition of alloy nanoparticles. The melting temperature of CuNi, PbBi and Snln binary alloy nanocrystals is found to be consistent with the experiments and molecular dynamics simulations. The research reveals that alloy nanocrystals have similar melting nature as pure metal.展开更多
基金Supported by the National High-Tech R&D Program of China(2011AA05A204)the Fundamental Research Funds for the Central Universities(222201717013)
文摘In this paper, the distributions of particle velocity in a gas–solid fluidized bed with branched pipe distributor or circle distributor were measured by using a laser Doppler velocimetry. Our results show that, within a certain range of superficial gas velocity, when using circle distributor, the particle velocity is large and the distribution of the particle velocity is even more compared with the branched pipe distributor. On the basis of the amplitude of tangential movement statistics, the amplitude of tangential movement statistics(AVATMS) decreases with increasing the axial height under the appropriate superficial gas velocity.
基金Project(2006AA03Z339)supported by the National High-tech Research and Development Program of ChinaProject(50571057)supported by the National Natural Science Foundation of ChinaProject(08520740500)supported by Science and Technology Commission of Shanghai Municipality,China
文摘Tin nanoparticles with different size distribution were synthesized using chemical reduction method by applying NaBH4 as reduction agent.The Sn nanoparticles smaller than 100 nm were less agglomerated and no obviously oxidized.The melting properties of these synthesized nanoparticles were studied by differential scanning calorimetry.The melting temperatures of Sn nanoparticles in diameter of 81,40,36 and 34 nm were 226.1,221.8,221.1 and 219.5？欲espectively.The size-dependent melting temperature and size-dependent latent heat of fusion have been observed.The size-dependent melting properties of tin nanoparticles in this study were also comparatively analyzed by employing different size-dependent theoretical melting models and the differences between these models were discussed.The results show that the experimental data are in accordance with the LSM model and SPI model,and the LSM model gives the better understanding for the melting property of the Sn nanoparticles.
基金supported by the Scientific Research Fund of Hunan Provincial Science & Technology Department (Grant No. 2009FJ3153)
文摘Based on the ideal solution approximation, the model for size-dependent melting temperature of pure metal nanoparticles is extended to binary alloy systems. The developed model, free of any adjustable parameter, demonstrates that the melting temperature is related to the size and composition of alloy nanoparticles. The melting temperature of CuNi, PbBi and Snln binary alloy nanocrystals is found to be consistent with the experiments and molecular dynamics simulations. The research reveals that alloy nanocrystals have similar melting nature as pure metal.
