Convective mass transfer coefficient for a hydrodynamically developed airflow in a short rectangular duct

An approximate approach was formulated to estimate the coefficient of convective mass transfer from small preshaped rectangular fragments of oil sands when subjected to hot streams of products of combustion of lean mixtures to hydrogen in air at low Reynolds number and at temperatures up to 1000 K. A simple expression which was derived to correlate the mass transfer coefficient in terms of the connective stream temperature was shown to fit the experimental data well.

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Effective diffusivity and convective mass transfer coefficient during the drying of bananas

Engenharia Agrícola ◽

10.1590/s0100-69162012000200014 ◽

2012 ◽

Vol 32 (2) ◽

pp. 342-353 ◽

Cited By ~ 8

Author(s):

Cleide M. D. P. da S. e Silva ◽

Wilton P. da Silva ◽

Vera S. de O. Farias ◽

Josivanda P. Gomes

Keyword(s):

Experimental Data ◽

Mass Transfer ◽

Boundary Condition ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Effective Diffusivity ◽

Convective Boundary Condition ◽

Drying Kinetics ◽

Convective Mass Transfer ◽

Convective Boundary

In this article, a methodology is used for the simultaneous determination of the effective diffusivity and the convective mass transfer coefficient in porous solids, which can be considered as an infinite cylinder during drying. Two models are used for optimization and drying simulation: model 1 (constant volume and diffusivity, with equilibrium boundary condition), and model 2 (constant volume and diffusivity with convective boundary condition). Optimization algorithms based on the inverse method were coupled to the analytical solutions, and these solutions can be adjusted to experimental data of the drying kinetics. An application of optimization methodology was made to describe the drying kinetics of whole bananas, using experimental data available in the literature. The statistical indicators enable to affirm that the solution of diffusion equation with convective boundary condition generates results superior than those with the equilibrium boundary condition.

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Convective Mass Transfer Coefficient at Wooden Surface in Jet Drying of Veneer

Holzforschung ◽

10.1515/hf.1999.034 ◽

1999 ◽

Vol 53 (2) ◽

pp. 204-208 ◽

Cited By ~ 4

Author(s):

Antti Hukka ◽

Olli Oksanen

Keyword(s):

Mass Transfer ◽

Moisture Content ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Heat And Mass Transfer ◽

Correction Factor ◽

Average Moisture Content ◽

Correction Coefficient ◽

Convective Mass Transfer ◽

Wooden Surface

Summary The relationship between heat and mass transfer at wooden surface is investigated experimentally by drying 1.6 mm thick birch veneers in constant conditions in a laboratory-scale roller dryer. By intermediate weighing of the samples a drying curve is established for each specimen. The drying curves are formulated in a functional form to produce the drying rate as a function of wood moisture content. Based on that and the measured heat-transfer coefficient a correction factor is calculated for the mass transfer coefficient predicted by the boundary layer theory. The results show that the convective mass transfer coefficient for wooden surfaces substantially deviates from that given by the analogy between heat and mass transfer. The correction factor describing the internal resistance for evaporation is strongly dependent on wood temperature within the range 50–90°C, but for practical purposes not dependent on the average moisture content of the veneer (range 40–70%). The numerical value of the correction coefficient established is somewhat lower than published earlier by other researchers.

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