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Measuring the liquid-solid mass transfer coefficient in packed beds using T2-T2 relaxation exchange NMR

Accepted version
Peer-reviewed

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Authors

Elgersma, SV 
Mantle, MD 
Gladden, LF 

Abstract

Direct measurement of the liquid–solid mass transfer coefficient in packed beds is achieved using T2-T2 relaxation exchange NMR. This method directly probes molecular exchange between intra- and inter-pellet fluid, rather than requiring a net flux between phases as in conventional methods. Mass transfer coefficients measured using the NMR method are compared with literature values and two widely used correlations. For Reynolds number, Re, less than 0.2, the mass transfer coefficients measured using NMR show excellent agreement with the correlations over the flow conditions for which they were developed. The approach also enables the quantification of mass transfer in the limit of, and at, zero flow. At Re= 0, the Sherwood number in packed beds with voidage of 0.41 determined by NMR is found to approach 9, in good agreement with previously reported results, but significantly greater than that predicted by extrapolating well-known correlations beyond their range of validity to Re= 0.

Description

Keywords

Liquid-solid mass transfer, Packed bed, Exchange NMR

Journal Title

Chemical Engineering Science

Conference Name

Journal ISSN

0009-2509
1873-4405

Volume Title

248

Publisher

Elsevier BV