Measurements of particle-to-gas mass transfer coefficients from chromatographic adsorption experiments

Wakao, Noriaki; Tanaka, Kenji; Nagai, Hiroaki

doi:10.1016/0009-2509(76)85020-8

Cited by 41 publications

(7 citation statements)

References 7 publications

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“…[14] lies between the value of 0.33 reported for mass transfer in liquids (7-9) and 0.6 reported for mass transfer in gases (10,11) at comparable Reynolds numbers. Since supercritical fluids have physical and transport properties which fall between those of liquids and gases, the exponent of 0.54 in Eq.…”

Section: Modelling Supercritical Co~ Extractionmentioning

confidence: 72%

“…Rapid convergence in the integration of Eqs. [11] and [12] is assured by using the modified Euler method and appropriate choices of At and Az (5). In our solution, which was obtained using a computer program designed to solve partial differential equations (6), typical values of At and Az were 60 s and 2 mm, respectively.…”

Section: Mathematical Model Of Fixed-bed Extractormentioning

confidence: 99%

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Modelling of supercritical carbon dioxide extraction of canola oilseed in fixed beds

Lee

Bulley

Fattori

et al. 1986

J Americ Oil Chem Soc

125

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Supercritical carbon dioxide extraction of oil from fixed beds (4.8 mm, 24.5 and 12.7 mm I.D.) of crushed canola seeds is described. Experiments were performed to obtain equilibrium data and extraction rates at 55 C, 36 MPa using solvent velocities ranging from 0.04 to 2.8 mm/s. A one‐dimensional, unsteady state mathematical model was used to obtain the oil concentration profiles in both the solvent and solid phases, and to determine the overall volumetric mass transfer coefficients. The calculated concentrations and extraction rates are in good agreement with experimental results. The overall volumetric mass transfer coefficient for the initial, constant rate extraction was correlated with interstitial velocity.

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Section: Modelling Supercritical Co~ Extractionmentioning

confidence: 72%

Section: Mathematical Model Of Fixed-bed Extractormentioning

confidence: 99%

Modelling of supercritical carbon dioxide extraction of canola oilseed in fixed beds

Lee

Bulley

Fattori

et al. 1986

J Americ Oil Chem Soc

125

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show abstract

“…All these correlations, based on results obtained from steady state experiments and various theoretical approaches, may give Sherwood estimates which differ from 1 to 4 orders of magnitude. Wakao and Tanisho [1974], Wakao et al [1976], and Wakao [1976] studied the external mass transfer coefficient in the transient state by the chromatographic method. They found Sherwood numbers as low as 0.01 suggesting a very slow external mass transfer rate.…”

Section: Discussionmentioning

confidence: 99%

Solute transport in porous media with solid‐liquid mass transfer limitations: Application to ion exchange

Nicoud¹,

Schweich²

1989

Water Resources Research

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Assuming that exchange equilibrium can be described by mass action laws, we show how to properly model the kinetic process with external and internal diffusion limitations using average concentrations and characteristic diffusion times. These characteristic diffusion times are defined as those used to describe linear interactions whereas the overall process is nonlinear due to the equilibrium constraints. The characteristic times are expressed in terms of the diffusion coefficients, characteristic dimensions of the exchanging aggregates, and relevant parameters of the flow regime. These expressions allow one to extrapolate laboratory measurements to field scale systems. The internal diffusion time is shown to be related to the selectivity factor. The analysis shows that external diffusion prevails in most situations, and specially at trace levels. A new criterion incorporating the nonlinear equilibrium law is proposed to determine whether the rate‐limiting step is internal or external diffusion.

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“…diffusion from the bulk fluid to the adsorbent surface (external diff.usion), diffusion within the porous particle (internal diffusion) and unsteadystate adsorption have been derived. The correlation of 1 tracer distribution, exiting the packed bed, with the model has been performed in the· time or Laplace domains (39,80,93,94,114,115,116) or by applying Fourier analysis 08,34,50,51,113). frequency response (23) order moments which grossly over-weight the scattered tail segment of the measured peak.…”

Section: Effective Diffusivitymentioning

confidence: 99%

“…The conversions listed. in Tables 3-6 were calculated by metho~s based on weight loss (equation113) and on analysis of the product gas mixture (equations [114][115][116]. The disagreement between the two methods suggests further pyrolysis may have occurred during the time the char was heated to reaction temperature or during gasification.…”

Section: Reaction Of Charmentioning

confidence: 99%

Influence of changing particle structure on the rate of gas-solid gasification reactions. Final report, July 1981-March 1984

1984

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Measurements of particle-to-gas mass transfer coefficients from chromatographic adsorption experiments

Cited by 41 publications

References 7 publications

Modelling of supercritical carbon dioxide extraction of canola oilseed in fixed beds

Modelling of supercritical carbon dioxide extraction of canola oilseed in fixed beds

Solute transport in porous media with solid‐liquid mass transfer limitations: Application to ion exchange

Influence of changing particle structure on the rate of gas-solid gasification reactions. Final report, July 1981-March 1984

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