Effect of temperature and reaction path interaction on fluidization reduction kinetics of iron ore powder

Due to the instability of FeO at temperatures below 843 K,the fuidization reduction pathway of iron ore powder changes with the reduction temperature.Thus,the effect of temperature and reaction pathway interaction on the kinetics of fuidization reduction of iron ore powder under low-temperature conditions ranging from 783 to 903 K was investigated to describe the fluidization reduction rate of iron ore powder from three aspects:microstructure change,reaction limiting link,and apparent activation energy of the reaction,exploring their internal correlation.The experimental results revealed that in a temperature range of 783-813 K,the formation of a dense iron layer hindered the internal diffusion of reducing gas,resulting in relatively high gas diffusion resistance.In addition,due to the differences in limiting links and reaction pathways in the intermediate stage of reduction,the apparent activation energy of the reaction varied.The apparent activation energy of the reaction ranged from 23.36 to 89.13 kJ/mol at temperature ranging from 783 to 813 K,while it ranged from 14.30 to 68.34 kJ/mol at temperature ranging from 873 to 903 K.

H2/CO/air premixed and partially premixed flame structure at different pressures based on reaction limit analysis

Premixed and partially premixed flames (PPFs) of H2/CO/air syngas are studied numerically to investigate the effect of pressure on syngas PPF structure. Chemical characteristics of the syngas flame at different pressures are investigated based on reaction limit analysis using a one-dimensional configuration. The results show that CO affects the syngas reaction limits through both physical effects that consist mainly in dilution and chemical effects that are related to both R23 (CO+OH=CO2+H) and HCO pathway. In particular, the HCO pathway weakens the flame at low pressures due to the chain-terminating effect of R25 (HCO+O2=CO+HO2) and R26 (HCO+H=CO+H2), and enhances the flame at high pressures because of the contribution of R25 to the HO2chain-branching process. These CO chemical characteristics are also observed in the premixed zone of 50%H2+50%CO syngas PPFs whereas only R23 is important in the non-premixed zone.

Numerical Approximation of a Reaction-Diffusion System with Fast Reversible Reaction

The authors consider the finite volume approximation of a reaction-diffusion system with fast reversible reaction.It is deduced from a priori estimates that the approximate solution converges to the weak solution of the reaction-diffusion problem and satisfies estimates which do not depend on the kinetic rate.It follows that the solution converges to the solution of a nonlinear diffusion problem,as the size of the volume elements and the time steps converge to zero while the kinetic rate tends to infinity.

PERIODIC REACTION AND TURBULENCE OF CHEMICAL BRUSSELATOR

In this paper, we discuss the reaction model of tri-molecules and the existence of periodic reaction under certain original density conditions of two objects without diffusion phenomena. We prove that the periodic reaction exhibit some chemical phenomena that violate the second law of thermo-mechanics. Finally, we research similar properties and phenomena concerning BelousovZhabotinsky reaction model.

1D/2D composite subnanometer channels for ion transport:The role of confined water

As a mass transport media,water is an alternative of organic solvent applied in rechargeable batteries,due to its unique properties,including fast ionic migration,easy-processibility,economic/environmental friendliness,and flame retardancy.However,due to the high activity of water molecules in aqueous electrolytes,the corrosion of metal anode,side reactions,and inferior metal electrodeposition behavior leads to unstable cycling performance,poor Coulombic efficiency(CE),and early-staged failure of batteries.Despite several attempts to regulate the activity of water,migration of ions is sacrificed,due to the limited methods to control the water states.Herein,we developed a subnanoscale confinement strategy based on a nacre-like structure to modulate the activity of water in the solid electrolytes.By tuning the ratio between the two-dimensional(2D)vermiculite and one-dimensional(1D)cellulose nanofibers(CNFs),the capillary size in the 1D/2D structure is altered to achieve a fast Zn^(2+)transport.Our dielectric relaxation and molecular dynamics studies indicate that the enhanced Zn^(2+)conductivity is attributed to the fast water relaxation in the precisely defined 1D/2D capillary.Taking advantage of the regulated activity of the confined water in 2D capillary,the composite vermiculite membrane can suppress the corrosion and side reactions between Zn electrode and water molecular,endowing a reversible Zn^(2+)stripping/plating behavior and a stable cycling performance for 900 h.Based on our confinement strategy to control the water states by 1D/2D structures,this work will open an avenue toward aqueous energy storage devices with excellent reversibility,high safety,and long-term stability.