Numerical Simulation for Direct Reduction of Pure Zinc Oxide Pellet Containing Carbon

2011 ◽  
Vol 194-196 ◽  
pp. 56-60
Author(s):  
Xiu Wei An ◽  
Jing Song Wang ◽  
Xue Feng She ◽  
Yin Gui Ding ◽  
Qing Guo Xue
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Zinc Oxide ◽  
Direct Reduction ◽  
Mass Conservation ◽  
Reaction Rates ◽  
Furnace Temperature ◽  
Pure Zinc ◽  
Rate Determining Step ◽  
Chemical Reaction Rates

Based on the equations of mass conservation, energy conservation and chemical reaction rates, a mathematical model of direct reduction for pure zinc oxide pellet containing carbon was built. On the basis of verifying the accuracy of the model by comparing calculated values with experimental results, the effects of furnace temperature, porosity and radius of pellet on the reduction were investigated. The calculated results revealed that the furnace temperature and the radius of pellet have significant effect while porosity has only a little. Thus it can be inferred that the rate-determining step for direct reduction in the pellet containing zinc oxide and carbon is heat transfer.

A Numerical Study of the Flame Stabilization Mechanism Being Determined by Chemical Reaction Rates Submitted to Heat Transfer Processes

2015 ◽  
Vol 229 (5) ◽  
Author(s):  
Guido Kuenne ◽  
Matthias Euler ◽  
Anja Ketelheun ◽  
Amer Avdić ◽  
Andreas Dreizler ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Chemical Reaction ◽  
Numerical Study ◽  
Three Dimensional ◽  
Thermal Conditions ◽  
Reaction Rates ◽  
Flame Stabilization ◽  
Detailed Chemistry ◽  
Physical Mechanisms ◽  
Chemical Reaction Rates

AbstractLarge Eddy Simulations of a turbulent lean premixed stratified burner are conducted in order to determine the physical mechanisms that dominate the flame stabilization close to burner walls. The purpose of this work is both to provide insight into the underlying physics as well as to check whether the deficiencies found in previous simulations are related to an inappropriate heat transfer treatment. The simulation utilizes a three-dimensional detailed chemistry database in order to capture the chemical reaction rates based on local mixing and thermal conditions. The study is supplemented by very accurate wall temperature measurements to remove the large uncertainty revealed in the past for this configuration. The results obtained from the simulations are evaluated by means of a qualitative illustration of the different flame stabilizations and comparisons with experimental data.

Research on Direct Reduction Dynamic Model of Carbon-Bearing Pellet Containing Zinc

2011 ◽  
Vol 214 ◽  
pp. 369-373
Author(s):  
Jing Song Wang ◽  
Xiu Wei An ◽  
Wan Hua Yu ◽  
Xue Feng She ◽  
Yin Gui Ding ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Direct Reduction ◽  
Reduction Process ◽  
Reduction Temperature ◽  
Coupled Heat Transfer ◽  
Reducing Gas ◽  
Metallization Rate ◽  
Process Factors

Base on reduction experimental data, considering the reduction process factors like carbon content, reductive removal of ZnO, changing size of pellet, and partial pressure of reducing gas, also coupled heat transfer, mass transfer and chemical reactions, a direct reduction mathematical model on carbon-bearing pellet containing zinc has been established. The reliability of the model was testified by programming and experiments. Experiments showed that, under the reduction conditions that carbon and oxygen mole ratio at 1.0 and reduction temperature 1603K, metallization rate 87% and dezincification rate 99% were observed after 15 minutes of heating.

scholarly journals The effects of gravitational potential on chemical reaction rates

2021 ◽  
Vol 2090 (1) ◽  
pp. 012034
Author(s):  
Paola Lecca
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
General Relativity ◽  
Gravitational Field ◽  
Rate Constants ◽  
Reaction Rates ◽  
Collision Theory ◽  
Kinetic Rate ◽  
Kinetic Rate Constants ◽  
Chemical Reaction Rates

Abstract This study aims to answer through a mathematical model and its numerical simulation the question whether the kinetic rate constants of chemical reactions are influenced by the strength of gravitational field. In order to calculate the effects of gravity on the kinetic rate constants, the model of kinetic rate constants derived from collision theory is amended by introducing the mass and length corrections provided by general relativity. Numerical simulations of the model show that the rate constant is higher where the gravitational field is more intense.

Low Temperature Deposition of Zinc Oxide Films

2003 ◽  
Vol 763 ◽  
Author(s):  
H. W. Lee ◽  
Y. G. Wang ◽  
S. P. Lau ◽  
B. K. Tay
Keyword(s):  
Zinc Oxide ◽  
Carrier Concentration ◽  
Vacuum Arc ◽  
Zno Films ◽  
Al Alloy ◽  
Pure Zinc ◽  
Zinc Oxide Films ◽  
Alloy Target ◽  
Temperature Deposition ◽  
Filtered Cathodic Vacuum Arc

AbstractA detailed study of zinc oxide (ZnO) films prepared by filtered cathodic vacuum arc (FCVA) technique was carried out. To deposit the films, a pure zinc target was used and O2 was fed into the chamber. The electrical properties of both undoped and Al-doped ZnO films were studied. For preparing the Al-doped films, a Zn-Al alloy target with 5 wt % Al was used. The resistivity, Hall mobility and carrier concentration of the samples were measured. The lowest resistivity that can be achieved with undoped ZnO films was 3.4×10-3 Ωcm, and that for Al-doped films was 8×10-4 Ωcm. The carrier concentration was found to increase with Al doping.

Design of the Blast Furnace Wall Structure Made of Efficient Materials. Part 4. Calculation Examples

2020 ◽  
Vol 786 (11) ◽  
pp. 30-34
Author(s):  
A.M. IBRAGIMOV ◽  
◽  
L.Yu. GNEDINA ◽  
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Blast Furnace ◽  
Boundary Value Problems ◽  
Transfer Process ◽  
Rational Design ◽  
Boundary Value ◽  
Heat Transfer Process ◽  
Furnace Wall ◽  
Time Interval

This work is part of a series of articles under the general title The structural design of the blast furnace wall from efficient materials [1–3]. In part 1, Problem statement and calculation prerequisites, typical multilayer enclosing structures of a blast furnace are considered. The layers that make up these structures are described. The main attention is paid to the lining layer. The process of iron smelting and temperature conditions in the characteristic layers of the internal environment of the furnace is briefly described. Based on the theory of A.V. Lykov, the initial equations describing the interrelated transfer of heat and mass in a solid are analyzed in relation to the task – an adequate description of the processes for the purpose of further rational design of the multilayer enclosing structure of the blast furnace. A priori the enclosing structure is considered from a mathematical point of view as the unlimited plate. In part 2, Solving boundary value problems of heat transfer, boundary value problems of heat transfer in individual layers of a structure with different boundary conditions are considered, their solutions, which are basic when developing a mathematical model of a non-stationary heat transfer process in a multi-layer enclosing structure, are given. Part 3 presents a mathematical model of the heat transfer process in the enclosing structure and an algorithm for its implementation. The proposed mathematical model makes it possible to solve a large number of problems. Part 4 presents a number of examples of calculating the heat transfer process in a multilayer blast furnace enclosing structure. The results obtained correlate with the results obtained by other authors, this makes it possible to conclude that the new mathematical model is suitable for solving the problem of rational design of the enclosing structure, as well as to simulate situations that occur at any time interval of operation of the blast furnace enclosure.

scholarly journals Mass and Heat Transfer Coefficients in Automotive Exhaust Catalytic Converter Channels

Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 507
Author(s):  
Chrysovalantis C. Templis ◽  
Nikos G. Papayannakos
Keyword(s):  
Heat Transfer ◽  
Flow Reactor ◽  
Catalytic Converter ◽  
Reaction Rates ◽  
Cfd Model ◽  
Automotive Exhaust ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Wide Range ◽  
Mass And Heat Transfer

Mass and heat transfer coefficients (MTC and HTC) in automotive exhaust catalytic monolith channels are estimated and correlated for a wide range of gas velocities and prevailing conditions of small up to real size converters. The coefficient estimation is based on a two dimensional computational fluid dynamic (2-D CFD) model developed in Comsol Multiphysics, taking into account catalytic rates of a real catalytic converter. The effect of channel size and reaction rates on mass and heat transfer coefficients and the applicability of the proposed correlations at different conditions are discussed. The correlations proposed predict very satisfactorily the mass and heat transfer coefficients calculated from the 2-D CFD model along the channel length. The use of a one dimensional (1-D) simplified model that couples a plug flow reactor (PFR) with mass transport and heat transport effects using the mass and heat transfer correlations of this study is proved to be appropriate for the simulation of the monolith channel operation.

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