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Modelling of multiphase multicomponent chemically reacting flows through packed beds

Modelling of multiphase multicomponent chemically reacting flows through packed beds
Modelling of multiphase multicomponent chemically reacting flows through packed beds
Currently used rocket propellants such as hydrazine, monomethylhydrazine, unsymmetrical dimethylhydrazine and nitrogen tetroxide are carcinogenic and toxic to the environment and therefore special protective measures are required when producing, transporting, storing and handling them. Employing alternatives could possibly save costs and this has revived the research interest in so called green propellants. Hydrogen peroxide is such a possible alternative. It requires a catalyst bed to decompose the liquid peroxide into steam and oxygen. The purpose of this work is to design numerical tools that describe the processes in the catalyst bed and subsequently employ these tools to predict the performance of the catalyst bed and investigate the influence of design choices on the performance. In contrast to the models described in the literature, the tools developed in this thesis are two fluid models. In order to test the reliability of the tools results are compared with experimental data. A single control volume two-fluid model has been developed to investigate the pressure drop over the catalyst bed and the influence of the shape and size of catalyst pellets on the pressure drop. Parametric studies with this model revealed that the Tallmadge equation gives a better prediction of the pressure gradient than the more traditionally employed Ergun equation. It was also found that for a given bed length cylindrical pellets with a diameter to length ratio of 2 or more give a lower pressure drop than cylindrical pellets, while achieving the same level of decomposition. A one-dimensional two-fluid model has been developed to obtain longitudinal variations of fluid properties. This model revealed that the catalyst bed can be divided into 3 sections: a pre-boiling region, rapid conversion region and a dry-out region. It was shown that most of the mass transfer takes place due to evaporation. A sensitivity analysis showed that the gas-liquid interfacial area hardly influences the results.
Koopmans, Robert-Jan
9ed266aa-63dd-451c-b52e-54cb4b464e1e
Koopmans, Robert-Jan
9ed266aa-63dd-451c-b52e-54cb4b464e1e
Roberts, Graham
deaf59ac-e4ee-4fc2-accf-df0639d39368

(2013) Modelling of multiphase multicomponent chemically reacting flows through packed beds. University of Southampton, Faculty of Engineering and the Environment, Doctoral Thesis, 200pp.

Record type: Thesis (Doctoral)

Abstract

Currently used rocket propellants such as hydrazine, monomethylhydrazine, unsymmetrical dimethylhydrazine and nitrogen tetroxide are carcinogenic and toxic to the environment and therefore special protective measures are required when producing, transporting, storing and handling them. Employing alternatives could possibly save costs and this has revived the research interest in so called green propellants. Hydrogen peroxide is such a possible alternative. It requires a catalyst bed to decompose the liquid peroxide into steam and oxygen. The purpose of this work is to design numerical tools that describe the processes in the catalyst bed and subsequently employ these tools to predict the performance of the catalyst bed and investigate the influence of design choices on the performance. In contrast to the models described in the literature, the tools developed in this thesis are two fluid models. In order to test the reliability of the tools results are compared with experimental data. A single control volume two-fluid model has been developed to investigate the pressure drop over the catalyst bed and the influence of the shape and size of catalyst pellets on the pressure drop. Parametric studies with this model revealed that the Tallmadge equation gives a better prediction of the pressure gradient than the more traditionally employed Ergun equation. It was also found that for a given bed length cylindrical pellets with a diameter to length ratio of 2 or more give a lower pressure drop than cylindrical pellets, while achieving the same level of decomposition. A one-dimensional two-fluid model has been developed to obtain longitudinal variations of fluid properties. This model revealed that the catalyst bed can be divided into 3 sections: a pre-boiling region, rapid conversion region and a dry-out region. It was shown that most of the mass transfer takes place due to evaporation. A sensitivity analysis showed that the gas-liquid interfacial area hardly influences the results.

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More information

Published date: 1 May 2013
Organisations: University of Southampton, Faculty of Engineering and the Environment

Identifiers

Local EPrints ID: 355889
URI: http://eprints.soton.ac.uk/id/eprint/355889
PURE UUID: ce5bb2b8-cef4-4f4d-bc5b-77ebea219849

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Date deposited: 18 Nov 2013 12:01
Last modified: 18 Jul 2017 03:43

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Contributors

Author: Robert-Jan Koopmans
Thesis advisor: Graham Roberts

University divisions

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