Imperial College London

Emeritus ProfessorGeoffreyHewitt

Faculty of EngineeringDepartment of Chemical Engineering

Emeritus Professor
 
 
 
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Contact

 

+44 (0)20 7594 5562g.hewitt

 
 
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Assistant

 

Mrs Sarah Payne +44 (0)20 7594 5567

 
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Location

 

507aACE ExtensionSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

224 results found

Angeli P, Hewitt GF, 1998, Pressure gradient in horizontal liquid-liquid flows, INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, Vol: 24, Pages: 1183-1203, ISSN: 0301-9322

Journal article

King MJS, Hale CP, Lawrence CJ, Hewitt GFet al., 1998, Characteristics of flowrate transients in slug flow, INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, Vol: 24, Pages: 825-854, ISSN: 0301-9322

Journal article

Pattison MJ, Martini R, Banerjee S, Hewitt GFet al., 1998, Modelling of dispersion of two-phase releases: Part I - Conservation equations and closure relationships, PROCESS SAFETY AND ENVIRONMENTAL PROTECTION, Vol: 76, Pages: 31-40, ISSN: 0957-5820

Journal article

Douek RS, Clerc AX, Hewitt GF, Livingston AGet al., 1998, Hydrodynamics of three-phase airlift(TPAL) reactors using viscous fluids, CHEMICAL ENGINEERING COMMUNICATIONS, Vol: 167, Pages: 205-225, ISSN: 0098-6445

Journal article

Soleimani A, Lawrence CJ, Hewitt GF, 1998, Effect of mixers on flow pattern and pressure drop in horizontal oil-water pipe flow, International Symposium on Liquid-Liquid 2 Phase Flow and Transport Phenomena, Publisher: BEGELL HOUSE, INC, Pages: 51-61

Conference paper

Kandlbinder T, Wadekar VV, Hewitt GF, 1998, Mixture effects for flow boiling of a binary hydrocarbon mixture, 11th International Heat Transfer Conference, Publisher: TAYLOR & FRANCIS LTD, Pages: 303-308

Conference paper

Pattison MJ, Martini R, Banerjee S, Hewitt GFet al., 1998, Modelling of dispersion of two-phase releases: Part 1 - Conservation equations and closure relationships, Process Safety and Environmental Protection, Vol: 76, Pages: 31-40, ISSN: 0957-5820

This paper presents a methodology for the prediction of the dispersion of a two-phase release from a chemical or process plant. A set of one-dimensional conservation equations for modelling such a release is derived, by taking an approach analogous to the boundary-layer integral method, in which the instantaneous conservation equations are averaged over a volume slice transverse to the direction of predominant plume/cloud motion. Averaging, which makes the problem computationally tractable, removes information regarding local gradients that govern transport of momentum, heat and mass - this information must then be supplied in the form of 'closure relationships'. An appropriate set of closure relationships is then discussed, covering models for interfacial heat and mass transfer, entrainment of air, and interactions with the wind field. Particular features of the approach are that it is flexible enough to deal with condensation of water vapour, thermal non-equilibrium between the phases, sloping terrain, and can handle both elevated and ground-bounded releases. Suitable formulations for the initial and source boundary conditions, for both instantaneous and continuous releases, are also presented. © Institution of Chemical Engineers.

Journal article

Hewitt GF, 1998, From gas-liquid to liquid-liquid two-phase flow: A difficult journey, International Symposium on Liquid-Liquid 2 Phase Flow and Transport Phenomena, Publisher: BEGELL HOUSE, INC, Pages: 3-19

Conference paper

Hewitt GF, 1998, Heat Exchanger Design Handbook, Publisher: Begell House

Book

Douek RS, Hewitt GF, Livingston AG, 1997, Hydrodynamics of vertical co-current gas-liquid-solid flows, CHEMICAL ENGINEERING SCIENCE, Vol: 52, Pages: 4357-4372, ISSN: 0009-2509

Journal article

Khor SH, MendesTatsis MA, Hewitt GF, 1997, One-dimensional modelling of phase holdups in three-phase stratified flow, INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, Vol: 23, Pages: 885-897, ISSN: 0301-9322

Journal article

Jayanti S, Hewitt GF, 1997, Hydrodynamics and heat transfer in wavy annular gas-liquid flow: A computational fluid dynamics study, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, Vol: 40, Pages: 2445-2460, ISSN: 0017-9310

Journal article

Hewitt GF, 1997, Keynote speech: Gas-liquid-liquid flow: A phase too far?, 8th International Conference on Multiphase 97, Publisher: MECHANICAL ENGINEERING PUBL, Pages: 215-240

Conference paper

Hewitt GF, Shires GL, Harrison PS, Parry SJet al., 1997, The MIXMETER flowmeter - another step towards routine multiphase flow measurement?, 8th International Conference on Multiphase 97, Publisher: MECHANICAL ENGINEERING PUBL, Pages: 385-406

Conference paper

King MJS, Hale CP, Fisher SA, Lawrence CJ, MendesTatsis MA, Hewitt GF, Roberts IFet al., 1997, Experimental investigations of flowrate transients in horizontal pipes, 8th International Conference on Multiphase 97, Publisher: MECHANICAL ENGINEERING PUBL, Pages: 419-435

Conference paper

Jayanti S, Hewitt GF, 1997, Hydrodynamics and heat transfer of wavy thin film flow, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, Vol: 40, Pages: 179-190, ISSN: 0017-9310

Journal article

Hewitt GF, 1997, International Encyclopaedia of Heat and Mass Transfer, Publisher: CRC Press

Book

Angeli P, Hewitt GF, 1996, Pressure gradient phenomena during horizontal oil-water flow, Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE, Vol: 5, Pages: 287-291

Pressure gradients were measured during the cocurrent dispersed flow of oil (1.6 mPa s viscosity) and water in two 1 inch nominal bore horizontal test sections made from stainless steel and acrylic resin. Measurements were made for mixture velocities above 1.1 m/s in the steel pipe and above 1.7 m/s in the acrylic pipe and up to 3.9 m/s, where fully dispersed flow exists (Angeli, 1996). Water volume fractions ranged from 5% to 85%, while phase inversion appeared between 37% and 40% water volume fraction in both pipes. Analysis of the results showed that the homogeneous model, where the mixture of the two fluids is treated as one 'pseudofluid' with properly averaged physical properties, cannot satisfactorily predict the pressure gradients occurring during the dispersed flow. Pressure gradients increased suddenly at the phase inversion point, while the experimental friction factors, especially in the oil continuous flows, appeared to be lower than the predictions of the homogeneous model or sometimes even lower than the single phase oil and water flow friction factors.

Journal article

Angeli P, Hewitt GF, 1996, Phase distribution measurements in liquid-liquid pipeline flows using an impedance probe, American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, Vol: 334, Pages: 149-153, ISSN: 0272-5673

A high frequency impedance probe was used for volume fraction distribution measurements and flow pattern identification in oil-water flow. The signal processing technique was based on a method by van der Welle (1985) that attributes to the beginning of the signal rise or fall the contact of the interface with the probe tip. The experiments were performed in two 1 inch nominal bore horizontal test sections made from stainless steel and acrylic resin. Measurements were made for mixture velocities from 1.3 m/s to 1.7 m/s and input oil volume fractions from 25% to 85%. Under these conditions different complex flow patterns exist, whose discrimination with visual observation is difficult. The results revealed that the mixing of the liquid phases is much greater in the rougher steel pipe than in the acrylic pipe under the same conditions and also helped to clearly identify the three layer, the stratified mixed and the fully mixed flow patterns.

Journal article

Hewitt GF, 1996, Multiphase flow: the gravity of the situation, NASA Conference Publication, Pages: 3-23, ISSN: 0191-7811

A brief survey is presented of flow patterns in two-phase, gas-liquid flows at normal and microgravity, the differences between them being explored. It seems that the flow patterns in zero gravity are in general much simpler than those in normal gravity with only three main regimes (namely bubbly, slug and annular flows) being observed. Each of these three regimes is then reviewed, with particular reference to identification of areas of study where investigation of flows at microgravity might not only be interesting in themselves, but also throw light on mechanisms at normal earth gravity. In bubbly flow, the main area of interest seems to be that of bubble coalescence. In slug flow, the extension of simple displacement experiments to the zero gravity case would appear to be a useful option, supplemented by computational fluid dynamics (CFD) studies. For annular flow, the most interesting area appears to be the study of the mechanisms of disturbance waves; it should be possible to extend the region of investigation of the onset and behaviour of these waves to much low gas velocities where measurements are clearly much easier.

Journal article

Hewitt GF, 1996, In search of two-phase flow, JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME, Vol: 118, Pages: 518-527, ISSN: 0022-1481

Journal article

Jayanti S, Tokarz A, Hewitt GF, 1996, Theoretical investigation of the diameter effect on flooding in countercurrent flow, INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, Vol: 22, Pages: 307-324, ISSN: 0301-9322

Journal article

Wolf A, Jayanti S, Hewitt GF, 1996, On the nature of ephemeral waves in vertical annular flow, INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, Vol: 22, Pages: 325-333, ISSN: 0301-9322

Journal article

Jayanti S, Hewitt GF, 1996, Response of turbulent flow to abrupt changes in surface roughness and its relevance in horizontal annular flow, APPLIED MATHEMATICAL MODELLING, Vol: 20, Pages: 244-251, ISSN: 0307-904X

Journal article

King MJS, Hale CP, MendesTatsis MA, Hewitt GFet al., 1996, An experimental investigation of flowrate transients within the slug flow regime in horizontal pipes, 7th International Conference on Pressure Surges and Fluid Transients in Pipelines and Open Channels, Publisher: MECHANICAL ENGINEERING PUBL, Pages: 29-46

Conference paper

Jayanti S, Kandlbinder T, Hewitt GF, 1996, Turbulent flow in a pipe with intermittent rough patches: An analogue of annular two-phase flow, CHEMICAL ENGINEERING COMMUNICATIONS, Vol: 141, Pages: 237-259, ISSN: 0098-6445

Journal article

Hewitt GF, 1996, Pheomenological issues in forced convective boiling, International Conference on Convective Flow Boiling, Publisher: TAYLOR & FRANCIS LTD, Pages: 3-14

Conference paper

Sun G, Chan WHGT, Hewitt GF, 1996, A general heat transfer model for two-phase annular flow, International Conference on Convective Flow Boiling, Publisher: TAYLOR & FRANCIS LTD, Pages: 193-198

Conference paper

DOUEK RS, LIVINGSTON AG, HEWITT GF, 1995, INSTABILITY PHENOMENON IN AN EXTERNAL-LOOP 3-PHASE GAS-LIQUID-SOLID AIRLIFT REACTOR, AICHE JOURNAL, Vol: 41, Pages: 2508-2511, ISSN: 0001-1541

Journal article

DOUEK RS, HEWITT GE, LIVINGSTON AG, 1995, A HYDRODYNAMIC STUDY OF THE RISER ZONE IN A 3-PHASE AIRLIFT (TPAL) REACTOR, 2nd International Conference on Gas-Liquid-Solid Reactor Engineering, Publisher: INST CHEMICAL ENGINEERS, Pages: 336-340, ISSN: 0263-8762

Conference paper

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