Correction to ‘Unsteady convective diffusion with interphase mass transfer’

1974 ◽  
Vol 341 (1626) ◽  
pp. 407-408 ◽  
Keyword(s):  
Mass Transfer ◽  
Convective Diffusion ◽  
Interphase Mass Transfer

In the above-specified paper (Sankarasubramanian & Gill 1973), equations (48 a ) and (75) should read I ( j, l ) = I ( l, j )= ∫ 1 0 y 3 J 0 ( μ j y ) J 0 ( μ l y d y = 2(2 β 2 + μ 2 j + μ 2 l / ( μ 2 j – μ 2 l ) 2 J 0 ( μ j ) J 0 ( μ l ) ( j ≠ l ), K 2 ≈ 1/( Pe ) 2 + 64(1+6/ β ) λ 2 1 Ʃ ∞ l =1 λ 2 l +1 / ( λ 2 l +1 – λ 2 1 ) 5∙

On the convective diffusion under partial slip at wall

1989 ◽  
Vol 54 (4) ◽  
pp. 967-980 ◽  
Author(s):  
Ondřej Wein ◽  
Petr Kučera
Keyword(s):  
Mass Transfer ◽  
Numerical Solution ◽  
Analytic Solution ◽  
Convective Diffusion ◽  
Linear Velocity ◽  
Partial Slip ◽  
Accurate Calculation ◽  
Transfer Coefficients ◽  
Empirical Formulas ◽  
Mass Transfer Coefficients

Extended Leveque problem is studied for linear velocity profiles, vx(z) = u + qz. The existing analytic solution is reconsidered and shown to be inapplicable for the accurate calculation of mean mass-transfer coefficients. A numerical solution is reported and its accuracy is checked in detail. Simple but fairly accurate empirical formulas are suggested for the calculating of local and mean mass-transfer coefficients.

scholarly journals Interpolation of Boundary Condition at Time-Interval of Unknown Lenghth for the Problem of Convective Diffusion in a Three-Layered Water Filter

2019 ◽  
pp. 25-28
Author(s):  
Olha Chernukha ◽  
Yurii Bilushchak
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Boundary Condition ◽  
Boundary Value Problem ◽  
Convective Diffusion ◽  
Lower Boundary ◽  
Time Interval ◽  
Water Filter ◽  
The Right

On the basis of mathematical model of convectivediffusion in a three-layered filter it is formulated a contactinitial-boundary value problem for description of mass transferof pollution accompanying the sorption processes. It is proposedthe algorithm for establishing the estimation of values of soughtfunction (concentration of pollution) at the lower boundary of thefilter on the basis of the interpolation of experimental data. It istaken into account that the right end of the interpolation segmentis unknown. It is determined the exact solutions of contact-initialboundaryvalue problems of mass transfer with provision forboth diffusive and convective mechanisms of transfer as well assorption processes, which is based on integral transformationsover space variables in the contacting regions. Is it designedsoftware and established regularities of convective diffusionprocess in the three-layered filter.

Intraphase diffusion and interphase mass transfer effects during the catalytic oxidation of CO in a tube wall reactor

1995 ◽  
Vol 448 (1933) ◽  
pp. 321-334 ◽  
Keyword(s):  
Activation Energy ◽  
Mass Transfer ◽  
Tube Wall ◽  
Catalyst Layer ◽  
Catalytic Conversion ◽  
Small Element ◽  
Transfer Effects ◽  
Transfer Resistance ◽  
Interphase Mass Transfer ◽  
Diffusive Resistance

Chemical kinetics of catalytic reactions are often obscured by intraphase diffusion and interphase mass transfer effects. Such complexities are especially true of catalytic combustion reactions effected within multichannel monoliths whose channel walls are coated with a catalyst layer. Assessment of the extent of intraphase and interphase resistances to the catalytic conversion of low concentrations of carbon monoxide in air were achieved by conducting experiments in a tube wall reactor, the walls of which were coated with a platinum-alumina deposit. Results indicated that, for a 1.34% CO in air mixture, kinetics below 610 K were less than first order with an activation energy of 30.4 kJ mol -1 . Above 610 K there was strong evidence of both intraphase and interphase resistances to catalytic conversion, the overall kinetics displaying an apparent activation energy of 11.7 kJ mol -1 . Near to the reactor tube entrance where the temperature was about 650 K, the mass transfer resistance from fluid to tube wall was only one-sixth that of the diffusive resistance within the thin catalyst washcoat, increasing to one half of the diffusive resistance at the tube exit where the temperature was about 820 K. Computer estimations of the performance of the tube wall reactor, using measured kinetic data for a small element of reactor containing catalyst deposited on the wall and interphase heat and mass transfer data estimated from first principles assuming laminar flow, are in satisfactory agreement with the measured performance of the whole tube wall reactor.

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