| EPSRC Reference: |
GR/M89034/01 |
| Title: |
NUCLEATE BOILING HEAT TRANSFER:EFFECT OF WALL PROPERTIES & SURFACE CONDITION |
| Principal Investigator: |
Kenning, Professor DBR |
| Other Investigators: |
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| Researcher Co-Investigators: |
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| Project Partners: |
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| Department: |
Engineering Science |
| Organisation: |
University of Oxford |
| Scheme: |
Standard Research (Pre-FEC) |
| Starts: |
01 November 1999 |
Ends: |
31 July 2003 |
Value (£): |
293,430
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| EPSRC Research Topic Classifications: |
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| EPSRC Industrial Sector Classifications: |
| Aerospace, Defence and Marine |
Chemicals |
| Electronics |
Energy |
| Transport Systems and Vehicles |
No relevance to Underpinning Sectors |
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| Panel History: |
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Summary on Grant Application Form |
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Boiling heat transfer occurs in a wide range of industrial activities: power generation, refrigeration, chemical processing and cooling systems for highly rated equipment such as electronics. Boiling bubbles nucleate at microcavities in the surface of the heated wall that are stable traps for vapour. Heat transfer coefficients depend strongly on the density of these nucleation sites but conventional roughness measurements are a poor guide to their activity. The thickness and thermal properties of the heated wall can also have large effects. The inadequate treatment of these influences causes large uncertainty in the correlation of experimental data currently used to design boiling equipment. This project will use a combination of recent developments in experimental methods and in computer modelling of boiling to develop improved design correlations, using measurements of wall conditions that can be made under industrial conditions.Paderborn University has studied boiling on heaters with specially prepared surfaces specified by additional analysis of roughness measurements. Oxford University can detect nucleation sites by the local temperature disturbances that they cause, measured by liquid crystal thermography, and by simple experiments on the nucleation of bubbles from unheated supersaturated gas solutions (a fizzy drink effect). First the relationship between boiling and gas nucleation and roughness measurements will be established in experiments on walls with laboratory-prepared surfaces. Then gas nucleation and roughness measurements will be made on a wide range of industrial boiling surfaces, on which it is often impossible to perform accurate boiling experiments. The results will be interpreted using large-scale computer models for boiling developed at Los Alamos National Laboratory and Ljubljana University. The models will be improved progressively and used in numerical experiments to explore the sensitivity of boiling to wall conditions over a wide range of conditions.The conditions in nucleate boiling are conductive to chaotic behaviour. It is not yet known whether this is of practical significance. Pioneering studies at Oxford over the last three years will be extended, drawing on the novel methods of non-linear analysis developed in the Mathematical Institute, Oxford for a wide range of systems with spatio-temporal variations.
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Key Findings |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Potential use in non-academic contexts |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Impacts |
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| Description |
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk |
| Summary |
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| Date Materialised |
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Sectors submitted by the Researcher |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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| Project URL: |
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| Further Information: |
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| Organisation Website: |
http://www.ox.ac.uk |