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

Pan L, Fisher SA, Jayanti S, Hewitt GFet al., 1995, Measurement and prediction of temperature rise following sudden compression in a high-pressure pipeline, Process Safety and Environmental Protection: Transactions of the Institution of Chemical Engineers, Part B, Vol: 73, Pages: 18-20, ISSN: 0957-5820

Theoretical and experimental studies were carried out on a possible compression ignition problem arising in an air supply line of 50.8 mm (2 inch) ID. A valve was used to close one end of the line and another valve located at a distance of 2.2m and connected to a high pressure air source was opened suddenly. The temperature of the air near the closed end was measured using a fast response thermocouple for a range of pressures. It was found that the measured temperature rise was much lower than that calculated thermodymically assuming isentropic compression of the low pressure air, but higher than that assuming complete mixing of the high and the low pressure air streams. Calculations using a transient flow simulation code (PLAC) also predicted values which were much higher than the measured ones. It is concluded that partial mixing of the two streams follows a sudden compression and that this effect must be properly accounted for in calculations to get an accurate estimate of temperature rises.

Journal article

PAN L, FISHER SA, JAYANTI S, HEWITT GFet al., 1995, MEASUREMENT AND PREDICTION OF TEMPERATURE RISE FOLLOWING SUDDEN COMPRESSION IN A HIGH-PRESSURE PIPELINE, PROCESS SAFETY AND ENVIRONMENTAL PROTECTION, Vol: 73, Pages: 18-20, ISSN: 0957-5820

Journal article

Manolis IG, MendesTatsis MA, Hewitt GF, 1995, The effect of pressure on slug frequency in two-phase horizontal flow, 2nd International Conference on Multiphase Flow, Publisher: ELSEVIER SCIENCE PUBL B V, Pages: 347-354

Conference paper

ROBERTS IF, HEWITT GF, HALL ARW, 1995, Simulation of transient three-phase flow, 7th International Conference on Multiphase Production, Publisher: MECHANICAL ENGINEERING PUBL, Pages: 219-239

Conference paper

PAN L, FISHER SA, JAYANTI S, HEWITT GFet al., 1995, MEASUREMENT AND PREDICTION OF TEMPERATURE RISE FOLLOWING SUDDEN COMPRESSION IN A HIGH-PRESSURE PIPE LINE, 1st European Conference for Young Researchers in Chemical Engineering - The 1995 IChemE Research Event, Publisher: INST CHEMICAL ENGINEERS, Pages: 74-76

Conference paper

MANOLIS IG, MENDESTATSIS MA, HEWITT GF, 1995, THE EFFECT OF PRESSURE ON FLOW PATTERN TRANSITION AND PRESSURE GRADIENT ON 2-PHASE HORIZONTAL SLUG FLOW, 1st European Conference for Young Researchers in Chemical Engineering - The 1995 IChemE Research Event, Publisher: INST CHEMICAL ENGINEERS, Pages: 847-849

Conference paper

KURBAN APA, MENDESTATSIS MA, HEWITT GF, 1995, OIL-WATER FLOWS IN HORIZONTAL TUBES, 1st European Conference for Young Researchers in Chemical Engineering - The 1995 IChemE Research Event, Publisher: INST CHEMICAL ENGINEERS, Pages: 757-759

Conference paper

KURBAN APA, ANGELI PA, MENDESTATSIS MA, HEWITT GFet al., 1995, Stratified and dispersed oil-water flows in horizontal pipes, 7th International Conference on Multiphase Production, Publisher: MECHANICAL ENGINEERING PUBL, Pages: 277-291

Conference paper

Hewitt GF, Delhaye JM, Zuber N, 1995, Multiphase Science and Technology, Publisher: Hemisphere Publishing Corporation

Book

DOUEK RS, LIVINGSTON AG, JOHANSSON AC, HEWITT GFet al., 1994, HYDRODYNAMICS OF AN EXTERNAL-LOOP 3-PHASE AIRLIFT (TPAL) REACTOR, CHEMICAL ENGINEERING SCIENCE, Vol: 49, Pages: 3719-3737, ISSN: 0009-2509

Journal article

PICKERING PF, LAHEY RT, HEWITT GF, 1994, AN EXPERIMENTAL STUDY OF INSTABILITIES IN A SUBATMOSPHERIC THERMOSYPHON LOOP, 10th International Heat Transfer Conference, Publisher: INST CHEMICAL ENGINEERS, Pages: 241-246

Conference paper

SUN G, WADEKAR VV, HEWITT GF, 1994, HEAT TRANSFER IN HORIZONTAL SLUG FLOW, 10th International Heat Transfer Conference, Publisher: INST CHEMICAL ENGINEERS, Pages: 271-276

Conference paper

Hewitt GF, Shires G, Bott TR, 1994, Process Heat Transfer, Publisher: Begell House Inc./CRC Press

Book

HALL ARW, HEWITT GF, 1993, APPLICATION OF 2-FLUID ANALYSIS TO LAMINAR STRATIFIED OIL-WATER FLOWS, INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, Vol: 19, Pages: 711-717, ISSN: 0301-9322

Journal article

HEWITT GF, JAYANTI S, 1993, TO CHURN OR NOT TO CHURN, INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, Vol: 19, Pages: 527-529, ISSN: 0301-9322

Journal article

JAYANTI S, HEWITT GF, LOW DEF, HERVIEU Eet al., 1993, OBSERVATION OF FLOODING IN THE TAYLOR BUBBLE OF COCURRENT UPWARDS SLUG FLOW, INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, Vol: 19, Pages: 531-534, ISSN: 0301-9322

Journal article

HEWITT GF, 1993, FLUID-DYNAMICS AND HEAT-TRANSFER IN ANNULAR 2-PHASE FLOW, 6th International Symposium on Transport Phenomena in Thermal Engineering (ISTP-VI), Publisher: BEGELL HOUSE, INC, Pages: 34-45

Conference paper

ZHANG Q, HEWITT GF, LESLIE DC, 1993, NUCLEAR SAFETY CODE MODELING OF CONDENSATION IN STRATIFIED FLOW, NUCLEAR ENGINEERING AND DESIGN, Vol: 139, Pages: 1-15, ISSN: 0029-5493

Journal article

Govan AH, Hewitt GF, 1992, Prediction of dryout using phenomenological models, Heat and Technology, Vol: 10, Pages: 1-43, ISSN: 0392-8764

It is well known that the phenomenon of dryout (used here to indicate any boiling crisis irrespective of the mechanism involved) may be caused by different mechanisms depending on the flow conditions, in particular the dryout quality. A great deal of research has been carried out on the annular two-phase flow regime and this has resulted in a rather successful model (see Hewitt and Govan) for high quality dryout in which a liquid film is completely evaporated and entrained. However, this model is unable to predict critical heat flux under subcooled or low quality conditions where the flow regime is not annular. Furthermore, some published work has suggested that at intermediate qualities there is a direct effect of heat flux on entrainment which is not included in the current annular flow model. This paper describes recent work aimed at modelling the dryout phenomenon over the entire range of conditions. A published model for low quality dryout (the DNB model of Weisman and Pei has been extended into the low quality annular flow regime by assuming that there is no re-entrainment of vapour from the gas core into the liquid film. The effect of nucleate boiling in annular flow was simulated in an air-water experiment and it was concluded that at low pressures boiling has no direct effect on entrainment. At higher pressures, on the other hand, data in the literature has shown such an effect and so a correlation was included in the annular flow model. The annular flow model was also modified to incorporate improved initial conditions. The ranges of applicability of the two (modified) models overlap, and it is shown that a combination of the two models can be used to obtain realistic predictions in a wide range of circumstances.

Journal article

JAYANTI S, HEWITT GF, 1992, PREDICTION OF THE SLUG-TO-CHURN FLOW TRANSITION IN VERTICAL 2-PHASE FLOW, INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, Vol: 18, Pages: 847-860, ISSN: 0301-9322

Journal article

HEWITT GF, JAYANTI S, 1992, PREDICTION OF FILM INVERSION IN 2-PHASE FLOW IN COILED TUBES, JOURNAL OF FLUID MECHANICS, Vol: 236, Pages: 497-511, ISSN: 0022-1120

Journal article

JAYANTI S, HEWITT GF, 1992, A NUMERICAL STUDY OF BIFURCATION IN LAMINAR-FLOW IN CURVED DUCTS, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Vol: 14, Pages: 253-266, ISSN: 0271-2091

Journal article

Hewitt GF, Delhaye JM, Zuber N, 1992, Post Dryout Heat Transfer, Publisher: CRC Press

Book

JAYANTI S, HEWITT GF, 1991, PREDICTION OF ONSET OF NUCLEATE BOILING, NET VAPOR GENERATION AND SUBCOOLED CHF IN COILED TUBES, WARME UND STOFFUBERTRAGUNG-THERMO AND FLUID DYNAMICS, Vol: 26, Pages: 301-305, ISSN: 0042-9929

Journal article

HEWITT GF, 1991, RESEARCH EVENT, CHEMICAL ENGINEERING RESEARCH & DESIGN, Vol: 69, Pages: 177-178, ISSN: 0263-8762

Journal article

JAYANTI S, HEWITT GF, 1991, ON THE PARADOX CONCERNING FRICTION FACTOR RATIO IN LAMINAR-FLOW IN COILS, PROCEEDINGS OF THE ROYAL SOCIETY-MATHEMATICAL AND PHYSICAL SCIENCES, Vol: 432, Pages: 291-299, ISSN: 0962-8444

Journal article

Hewitt GF, Mayinger F, Risnic JR, 1991, Phase-Interface Phenomena in Multiphase Flow, Publisher: Hemisphere Publishing Corporation

Book

Hewitt GF, Govan AH, 1990, Phenomena and prediction in annular two-phase flow, American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED, Vol: 99, Pages: 41-56

A survey is presented of recent experimental and analytical work carried out under a joint programme at the Harwell Laboratory and Imperial College, placing the new work into the context of earlier developments. The basic balance equations for annular flow are introduced and the well-known triangular relationship reiterated. Then, interfacial waves and interfacial friction are reviewed, including some new results in both areas. A key feature in annular flow is the prediction of deposition and entrainment and recent developments are described. The various studies have led to a new framework for predictions of annular flow systems and the application of this framework to adiabatic flows, evaporating flows, steady-state dryout and transient dryout is described. Finally, new models covering the full range of dryout (CHF) ranging from subcooled conditions to high quality conditions are described; here dryout is limited by either film dryout (in annular flow) or by bubble wall crowding (at low quality) and the new modelling structure allows a natural transition between the two.

Journal article

HEWITT GF, JAYANTI S, HOPE CB, 1990, STRUCTURE OF THIN LIQUID-FILMS IN GAS-LIQUID HORIZONTAL FLOW, INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, Vol: 16, Pages: 951-957, ISSN: 0301-9322

Journal article

JAYANTI S, HEWITT GF, WHITE SP, 1990, TIME-DEPENDENT BEHAVIOR OF THE LIQUID-FILM IN HORIZONTAL ANNULAR-FLOW, INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, Vol: 16, Pages: 1097-1116, ISSN: 0301-9322

Journal article

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