期刊文献+
共找到5篇文章
< 1 >
每页显示 20 50 100
Developments in the understanding of gas–solid contact efficiency in the circulating fluidized bed riser reactor:A review 被引量:6
1
作者 Chengxiu Wang Jesse Zhu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第1期53-62,共10页
In the last several decades, circulating fluidized bed reactors have been studied in many aspects including hydrodynamics, heat and mass transfer and gas–solid two phase contacting. However, despite the abundance of ... In the last several decades, circulating fluidized bed reactors have been studied in many aspects including hydrodynamics, heat and mass transfer and gas–solid two phase contacting. However, despite the abundance of review papers on hydrodynamics, there is no summary paper on gas–solid contact efficiency to date, especially on high density circulating fluidized beds(CFBs). This paper gives an introduction to, and a review of the measurement of contact efficiency in circulating fluidized bed riser. Firstly, the popular testing method of contact efficiency including the method of heating transfer experiment and hot model reaction are discussed, then previous published papers are reviewed based on the discussed methods. Some key results of the experimental work are described and discussed. Gas–solid contact efficiency is affected by the operating conditions as well as the particle size distribution. The result of the contact efficiency shows that the CFB riser is far away from an ideal plug flow reactor due to the characteristics of hydrodynamics in the riser. Lacunae in the available literature have been delineated and recommendations have been made for further work. 展开更多
关键词 Circulating fluidized bed Riser High density Gas–solid contacting Heat transfer Ozone decomposition
下载PDF
First-principles calculations of structural and electronic properties of Tl_xGa_(1-x)As alloys
2
作者 G. Bilgec akyüz A. Y. Tunali +1 位作者 S. E. Gulebaglan N. B. Yurdasan 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第2期377-383,共7页
The zincblende ternary alloys Tl_xGa_(1-x) As(0 〈 x 〈 1) are studied by numerical analysis based on the plane wave pseudopotential method within the density functional theory and the local density approximation.... The zincblende ternary alloys Tl_xGa_(1-x) As(0 〈 x 〈 1) are studied by numerical analysis based on the plane wave pseudopotential method within the density functional theory and the local density approximation. To model the alloys,16-atom supercells with the 2 × 2 × 2 dimensions are used and the dependency of the lattice parameter, bulk modulus,electronic structure, energy band gap, and optical bowing on the concentration x are analyzed. The results indicate that the ternary Tl_xGa_(1-x) As alloys have an average band gap bowing parameter of 4.48 eV for semiconductor alloys and 2.412 eV for semimetals. It is found that the band gap bowing strongly depends on composition and alloying a small Tl content with GaAs produces important modifications in the band structures of the alloys. 展开更多
关键词 methods of electronic structure calculations electron density of states and band structure of crys-talline solids electronic structure of disordered solid
下载PDF
First-principles study of the co-effect of carbon doping and oxygen vacancies in ZnO photocatalyst
3
作者 Jia Shi Lei Wang Qiang Gu 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第2期419-425,共7页
Although tuning band structure of optoelectronic semiconductor-based materials by means of doping single defect is an important approach for potential photocatalysis application,C-doping or oxygen vacancy(Vo)as a sing... Although tuning band structure of optoelectronic semiconductor-based materials by means of doping single defect is an important approach for potential photocatalysis application,C-doping or oxygen vacancy(Vo)as a single defect in ZnO still has limitations for photocatalytic activity.Meanwhile,the influence of co-existence of various defects in ZnO still lacks sufficient studies.Therefore,we investigate the photocatalytic properties of ZnOx C0.0625(x=0.9375,0.875,0.8125),confirming that the co-effect of various defects has a greater enhancement for photocatalytic activity driven by visible-light than the single defect in ZnO.To clarify the underlying mechanism of co-existence of various defects in ZnO,we perform systematically the electronic properties calculations using density functional theory.It is found that the coeffect of C-doping and Vo in ZnO can achieve a more controllable band gap than doping solely in ZnO.Moreover,the impact of the effective masses of ZnO_(x)C_(0.0625)(x=0.9375,0.875,0.8125)is also taken into account.In comparison with heavy Vo concentrations,the light Vo concentration(x=0.875)as the optimal component together with C-doping in ZnO,can significantly improve the visible-light absorption and benefit photocatalytic activity. 展开更多
关键词 first-principles theory electron density of states and band structure of crystalline solids Ⅲ-ⅤandⅡ-Ⅵsemiconductors
下载PDF
Study of magnetic and optical properties of Zn1-xTMxTe(TM = Mn,Fe,Co,Ni) diluted magnetic semiconductors:First principle approach
4
作者 Q Mahmood M Hassan M A Faridi 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第2期452-460,共9页
We present structural,magnetic and optical characteristics of Zn_(1-x)TM_xTe(TM = Mn,Fe,Co,Ni and x = 6.25%),calculated through Wien2 k code,by using full potential linearized augmented plane wave(FP-LAPW) techn... We present structural,magnetic and optical characteristics of Zn_(1-x)TM_xTe(TM = Mn,Fe,Co,Ni and x = 6.25%),calculated through Wien2 k code,by using full potential linearized augmented plane wave(FP-LAPW) technique.The optimization of the crystal structures have been done to compare the ferromagnetic(FM) and antiferromagnetic(AFM) ground state energies,to elucidate the ferromagnetic phase stability,which further has been verified through the formation and cohesive energies.Moreover,the estimated Curie temperatures T_c have demonstrated above room temperature ferromagnetism(RTFM) in Zn_(1-x)TM_xTe(TM =Mn,Fe,Co,Ni and x= 6.25%).The calculated electronic properties have depicted that Mn- and Co-doped ZnTe behave as ferromagnetic semiconductors,while half-metallic ferromagnetic behaviors are observed in Fe- and Ni-doped ZnTe.The presence of ferromagnetism is also demonstrated to be due to both the p-d and s-d hybridizations between the host lattice cations and TM impurities.The calculated band gaps and static real dielectric constants have been observed to vary according to Penn's model.The evaluated band gaps lie in near visible and ultraviolet regions,which make these materials suitable for various important device applications in optoelectronic and spintronic. 展开更多
关键词 magnetic semiconductors density functional theory optical and dielectric properties electron density of states and band structure of crystalline solids
下载PDF
Application of CFD-DEM to the study of solid exchange in a dual-leg fluidized bed
5
作者 Chunzhen Yang Yufeng Duan Haitao Hu 《Particuology》 SCIE EI CAS CSCD 2013年第6期636-646,共11页
The CFD-DEM model was developed to simulate solid exchange behavior between two half beds in a bench-scale two-dimensional dual-leg fluidized bed (DL-FB). Power spectrum density (PSD) analysis was applied to obtai... The CFD-DEM model was developed to simulate solid exchange behavior between two half beds in a bench-scale two-dimensional dual-leg fluidized bed (DL-FB). Power spectrum density (PSD) analysis was applied to obtain the dominant frequency (F) of the simulated differential particle number (APLR) between the two half beds. Effects of fluidization velocity (u) and bed material inventory (H) on the solid exchange behavior were studied using the CFD-DEM model. Not only snapshots of the simulated particle flow patterns using the OpenGL code but also the dominant frequency of APLR was similar to the experimental results. The simulation results show that higher fluidization velocity assists the exchange of more particles between the two half beds, but the dispersion of clusters on the bed surface into single particles decreases the cluster exchange frequency. A greater bed material inventory results in more intense cluster exchange. The cluster exchange frequency decreases with an increase of the bed material inventory. 展开更多
关键词 Dual legs Fluidized bed solid exchange Discrete element method Power spectrum density
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部