scholarly journals Homogeneous–Heterogeneous Reactions in Boundary-Layer Flow of a Nanofluid Near the Forward Stagnation Point of a Cylinder

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Qingkai Zhao ◽  
Hang Xu ◽  
Longbin Tao
Keyword(s):  
Stagnation Point ◽  
Diffusion Coefficients ◽  
Multiple Solutions ◽  
Heterogeneous Reaction ◽  
Heterogeneous Reactions ◽  
Homogeneous Reaction ◽  
First Order ◽  
First Order Kinetics ◽  
Layer Flow ◽  
Cubic Autocatalator

A mathematical model describing the homogeneous–heterogeneous reactions in the vicinity of the forward stagnation point of a cylinder immerged in a nanofluid is established. We assume that the homogeneous reaction is given by isothermal cubic autocatalator kinetics, while the heterogeneous reaction is chosen as first-order kinetics. The existence of multiple solutions through hysteresis bifurcations is discussed in detail for the various diffusion coefficients of reactant and autocatalyst.

scholarly journals Stagnation Flow of a SWCNT Nanofluid towards a Plane Surface with Heterogeneous-Homogeneous Reactions

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Sohail Ahmed ◽  
Hang Xu ◽  
Qiang Sun
Keyword(s):  
Plane Surface ◽  
Heterogeneous Reaction ◽  
Heterogeneous Reactions ◽  
Physical Parameters ◽  
Nanofluid Flow ◽  
Flow Models ◽  
First Order ◽  
Bulk Reaction ◽  
Layer Flow ◽  
Walled Carbon Nanotubes

The homogeneous-heterogeneous reaction in the boundary layer flow of a water-based nanofluid in the stagnation-point region of a plane surface is investigated. The type of small particles explored here is the single-walled carbon nanotubes. The homogeneous nanofluid model is employed for description of behaviours of nanofluids. Here, the homogeneous (bulk) reaction is isothermal cubic autocatalytic, while the heterogeneous (surface) reaction is single, isothermal, and first order. The steady state of this system is analysed in detail, with equal diffusion coefficients being considered for both reactants and autocatalysts. Multiple solutions of the reduced system are captured for some particular sets of physical parameters, which seem to be overlooked in all previous published works with regard to studies of homogeneous-heterogeneous reactions modeled by homogeneous nanofluid models. Besides, we discover the significant limitation of previous conclusion about that the solutions by homogeneous nanofluid flow models can be recovered from those by regular fluids.

Homogeneous–Heterogeneous Reactions of Blasius Flow in a Nanofluid

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Hang Xu
Keyword(s):  
Mathematical Model ◽  
Diffusion Coefficients ◽  
Multiple Solutions ◽  
Transport Mechanism ◽  
Heterogeneous Reactions ◽  
Nonlinear Ordinary Differential Equations ◽  
Blasius Flow ◽  
Homogeneous And Heterogeneous Reactions ◽  
Heterogeneous Chemical ◽  
Heterogeneous Chemical Reactions

An investigation is made to study the Blasius flow of a nanofluid in the presence of homogeneous–heterogeneous chemical reactions. Here, the diffusion coefficients of the reactant and autocatalyst are considered to be in comparable sizes. The Buongiorno's mathematical model is applied in describing the behavior of nanofluids. Multiple solutions of the steady-state system of nonlinear ordinary differential equations are obtained. Results show that nanofluids significantly participate in the transport mechanism of the homogeneous–heterogeneous reactions, which play different roles in the procedures of homogeneous and heterogeneous reactions.

Heterogeneous reaction of nitric acid with methyl sulfide

1985 ◽  
Vol 63 (10) ◽  
pp. 2805-2807
Author(s):  
Donald L. Singleton ◽  
Robert S. Irwin ◽  
Donald J. McKenney ◽  
George Paraskevopoulos
Keyword(s):  
Gas Chromatography ◽  
Infrared Spectroscopy ◽  
Nitric Acid ◽  
Initial Rate ◽  
Heterogeneous Reaction ◽  
Zero Order ◽  
Homogeneous Reaction ◽  
Gaseous Mixtures ◽  
First Order ◽  
Upper Limit

The reaction of gaseous mixtures of CH3SCH3 and HNO3, studied by infrared spectroscopy and gas chromatography, was found to occur heterogeneously. The products detected were NO2 and CH3S(O)CH3, and approximately one NO2 was formed for each CH3SCH3 consumed. The initial rate of formation of NO2 was first order in CH3SCH3 and zero order in HNO3. The mechanism is discussed, and an upper limit is determined for the rate constant of the homogeneous reaction.

Effects of Homogeneous–Heterogeneous Reactions on the Viscoelastic Fluid Toward a Stretching Sheet

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
W. A. Khan ◽  
I. M. Pop
Keyword(s):  
Boundary Layer ◽  
Viscoelastic Fluid ◽  
Diffusion Coefficients ◽  
Stretching Sheet ◽  
Equations Of Motion ◽  
Heterogeneous Reactions ◽  
Viscoelastic Parameter ◽  
Implicit Finite Difference ◽  
Layer Flow ◽  
Basic Boundary

The effects of homogeneous–heterogeneous reactions on the steady viscoelastic fluid toward a stretching sheet are numerically investigated in this paper. The model developed by Chaudhary and Merkin for homogeneous–heterogeneous reactions in stagnation-point boundary-layer flow with equal diffusivities for reactant and autocatalyst is used for present stretching sheet problem in a viscoelastic fluid. The basic boundary layer partial differential equations of motion and concentration are reduced to ordinary differential (similarity) equations, which then are numerically solved using an implicit finite difference method in the case when the diffusion coefficients of both reactant and autocatalyst are equal. It is found that the concentration at the surface decreases with an increase in the viscoelastic parameter and strengths of the homogeneous, while heterogeneous reactions increase.

THE KINETICS OF THE THERMAL DECOMPOSITION OF DISULPHUR DECAFLUORIDE

1951 ◽  
Vol 29 (6) ◽  
pp. 508-525 ◽  
Author(s):  
W. R. Trost ◽  
R. L. McIntosh
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Heterogeneous Reaction ◽  
Homogeneous Reaction ◽  
Chain Reaction ◽  
First Order ◽  
Reaction Proceeds ◽  
Total Process ◽  
A Chain ◽  
Kinetics Of

The thermal decomposition of the gas disulphur decafluoride has been studied in a metal reactor. Analytical evidence showed that the reaction proceeds according to the equation S2F10 = SF6 + SF4.The reaction was found to be largely homogeneous, as the heterogeneous reaction accounted for less than 5% of the total process. The homogeneous reaction was shown to be first order, and in the temperature range investigated the rate is given by ln k = 47.09 − 49,200/RT. A chain reaction is postulated to explain the observed rate of the reaction. The effect of nitric oxide and acetylene dichloride on the rate and products of the reaction was investigated.

scholarly journals Bödewadt Flow Over a Permeable Disk with Homogeneous-Heterogeneous Reactions: A Numerical Study

2019 ◽  
Vol 9 (19) ◽  
pp. 4046 ◽  
Author(s):  
Talat Rafiq ◽  
Meraj Mustafa Hashmi
Keyword(s):  
Chemical Reaction ◽  
Numerical Study ◽  
Exact Formula ◽  
Heterogeneous Reactions ◽  
Concentration Boundary ◽  
First Order Kinetics ◽  
Mass Transfer Parameter ◽  
Bulk Reaction ◽  
Self Similar ◽  
Cubic Autocatalator

We analyzed the onset of homogeneous-heterogeneous reactions in Bödewadt flow occurring over an isothermal and permeable surface. This research is based on the assumption that the homogeneous (bulk) reaction follows isothermal cubic autocatalator kinetics, whereas the surface reaction is governed by first-order kinetics. The heat energy released during the chemical reaction is assumed to be negligible. The governing equations are reducible to a set of self-similar equations, which are handled numerically. Asymptotic analysis was conducted, which revealed that the existence of a concentration boundary layer on the disk is possible only when the disk is subjected to a sufficient amount of suction. In a large suction situation, an exact formula for concentration profile ϕ was derived that strongly supports the obtained numerical solution. Our results demonstrate the mass transfer parameter considerably alters flow fields. The concentration at the wall varies substantially when the chemical reaction proceeds at a faster rate.

Multiple Solutions of an Unsteady Stagnation-Point Flow with Melting Heat Transfer in a Darcy–Brinkman Porous Medium

2016 ◽  
Vol 0 (0) ◽  
Author(s):  
M Khalid Aurangzaib ◽  
Bhattacharyya Krishnendu ◽  
Shafie Sharidan
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Differential Equations ◽  
Stagnation Point ◽  
Multiple Solutions ◽  
Melting Heat ◽  
Similarity Transformations ◽  
Melting Heat Transfer ◽  
Self Similar ◽  
Layer Flow

AbstractThe characteristics of the unsteady boundary layer flow with melting heat transfer near a stagnation-point towards a flat plate embedded in a DarcyBrinkman porous medium with thermal radiation are investigated. The governing partial differential equations are transformed into self-similar ordinary differential equations by similarity transformations. The transformed self-similar equations are solved numerically using bvp4c from Matlab for several values of the flow parameters. The study reveals that the multiple solutions exist for the decelerating (

Heat and Mass Transfer Analysis in the Stagnation Region of Maxwell Fluid With Chemical Reaction Over a Stretched Surface

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Tasawar Hayat ◽  
Muhammad Ijaz Khan ◽  
Maria Imtiaz ◽  
Ahmed Alsaedi
Keyword(s):  
Maxwell Fluid ◽  
Deborah Number ◽  
Ambient Fluid ◽  
Stagnation Region ◽  
Heterogeneous Process ◽  
First Order ◽  
First Order Kinetics ◽  
Heterogeneous Processes ◽  
Physical Quantities ◽  
Cubic Autocatalator

A simple model of homogeneous–heterogeneous process for Maxwell fluid flow in stagnation region past a stretched surface is constructed. It is assumed that the homogeneous process in the ambient fluid is governing by first-order kinetics and the heterogeneous process on the wall surface is given by isothermal cubic autocatalator kinetics. Flow by stretched surface with homogeneous–heterogeneous processes studied. Present problem is reduced to ordinary differential equations through appropriate transformation. Resulting problems have been solved for convergent solutions. Intervals of convergence for the obtained series solutions are explicitly determined. Behavior of important variables on the physical quantities is analyzed. Velocity is found decreasing function of Deborah number.

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