Towards an understanding of mass transfer and hydrodynamics in packed bed reactors using Nuclear Magnetic Resonance
type: CreativeWork
description: This thesis presents the implementation and development of nuclear magnetic resonance (NMR) techniques to study mass transfer and hydrodynamic phenomena that govern the performance of packed bed reactors. The aim of this work is to gain insight into factors that affect the process of fines deposition and mass transfer inside packed beds to ultimately enable optimisation of these processes. Although mass transfer correlations exist for pure components and mixtures, previous studies have failed to measure the mass transfer coefficient in situ without extensive pre-calibration. In this thesis, the T2-T2 method is used to measure in situ mass transfer coefficients for single components and mixtures without any prior calibration. For mixtures, the standard T2-T2 method was modified to achieve chemical selectivity. Both single component and mixture mass transfer coefficients were found to be in accordance with a semi-theoretical correlation. Moreover, depending on the Reynolds (𝑅𝑒) and Schmidt (𝑆𝑐) numbers characterising the systems, it was illustrated that traditional mass transfer correlations can under-predict mass transfer coefficients in excess of 96% due to incorrect assumptions. For accurate design or modelling of packed beds characterised by low 𝑅𝑒 and 𝑆𝑐, this highlights the need for reconsidering the use of traditional mass transfer correlations. In addition, despite mass transfer correlations existing for mixtures, none address the non-ideal mixture effects upon the mass transfer coefficient. Although the chemically selective T2-T2 method was validated using ideal gas mixtures, some suggestions were offered for non-ideal mixtures that this pulse sequence can study in the future. Despite a plethora of existing studies on fines deposition, none have experimentally validated the pore-scale nature of deposits in realistic packed beds; neither have they considered how the mass transfer rate is affected by deposits. For the first time, through the combination of NMR …
abstract: This thesis presents the implementation and development of nuclear magnetic resonance (NMR) techniques to study mass transfer and hydrodynamic phenomena that govern the performance of packed bed reactors. The aim of this work is to gain insight into factors that affect the process of fines deposition and mass transfer inside packed beds to ultimately enable optimisation of these processes. Although mass transfer correlations exist for pure components and mixtures, previous studies have failed to measure the mass transfer coefficient in situ without extensive pre-calibration. In this thesis, the T2-T2 method is used to measure in situ mass transfer coefficients for single components and mixtures without any prior calibration. For mixtures, the standard T2-T2 method was modified to achieve chemical selectivity. Both single component and mixture mass transfer coefficients were found to be in accordance with a semi-theoretical correlation. Moreover, depending on the Reynolds (𝑅𝑒) and Schmidt (𝑆𝑐) numbers characterising the systems, it was illustrated that traditional mass transfer correlations can under-predict mass transfer coefficients in excess of 96% due to incorrect assumptions. For accurate design or modelling of packed beds characterised by low 𝑅𝑒 and 𝑆𝑐, this highlights the need for reconsidering the use of traditional mass transfer correlations. In addition, despite mass transfer correlations existing for mixtures, none address the non-ideal mixture effects upon the mass transfer coefficient. Although the chemically selective T2-T2 method was validated using ideal gas mixtures, some suggestions were offered for non-ideal mixtures that this pulse sequence can study in the future. Despite a plethora of existing studies on fines deposition, none have experimentally validated the pore-scale nature of deposits in realistic packed beds; neither have they considered how the mass transfer rate is affected by deposits. For the first time, through the combination of NMR …
author: Klotz, Adeline Rachelle
language: en
keywords: mass transfer, hydrodynamics, nuclear magnetic resonance, packed bed reactor
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/913d3bcf-c53e-4591-8861-c4652d5f7729/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2019-07-19
date modified: 2026-07-22T22:24:10Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.41546