Condensation On Low-Finned Tubes

Completed

Energy Efficiency(Residential and commercial)

Basic and strategic applied research

ENGINEERING AND TECHNOLOGY (Mechanical, Aeronautical and Manufacturing Engineering)

Not Cross-cutting

Professor J Rose
Engineering and Materials Science
Queen Mary University of London

Standard

EPSRC

01 July 2005

30 September 2006

15 months

£70,774

Energy

London

Engineering science: flow -- Process Environment and Sustainability

Professor J Rose, Engineering and Materials Science, Queen Mary University of London

Dr H Wang, Engineering and Materials Science, Queen Mary University of London

Refrigeration and air conditioning account for a substantial proportion of the energy consumption of the UK and other developed counties. Efforts have been made in recent years to improve plant performance for fuel economy and reduction in carbon dioxide emissions. The problem has been exacerbated by the necessity to discontinue use of ozone depleting fluids. Several replacement refrigerants are now in wide use but some have significant global warming potential and their long-term future is indoubt. The condenser is a major component of refrigeration plant and for design purposes it is necessary to predict accurately the heat transfer performance of enhanced condenser tubes for any given fluid.Low integral fin condenser tubes are now widely used in modern plant. Design calculations are presently based on correlations of experimental data for former ozone-depleting fluids and their current replacements. Theoretical solution is problematic owing to the crucial role played by surfacetension and curvature of the condensate surface which various in a complicated way over the fin and tube surface.Theoretical efforts to provide methods valid for any fluid have been partially successful but to date no wholly-theoretical and complete solution has been achieved. One of the present investigators (JWR) has proposed a theoretically-based method which is now widely used and has been adopted as the recommended design method by ESDU International plc. Before joining Professor Rose atQMUL the second investigator, Dr Wang, worked for three years with Professor Honda at Kyushu University. Professor Honda's earlier theoretical work on this problem is accepted as the most complete to date but suffers from acknowledged deficiencies. While at Kyushu, Dr Wang worked with Professor Honda on an unsuccessful attempt to overcome significant theoretical problems. In the course of their (EPSRC supported) work on condensation in microchannels, methods have been developed by the present investigators which should be adaptable for solution of the problem of condensation on integral fin tubes. We believe that we are uniquely placed to provide a complete theoretical solution to the problem in approximately one year. The results will be valid for any new refrigerants which may be developed to satisfy both ozone depletion and global warming constraints. If time permits we shall extend the solution to mixtures of vapours and effects of vapour velocity

01/01/07