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ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

DRAG-REDUCTION AND HEAT TRANSFER CHARACTERISTICS OF A NOVEL ZWITTERIONIC SURFACTANT SOLUTION

Get access (open in a dialog) DOI: 10.1615/IHTC13.p20.200
9 pages

要約

Addition of small amounts of surfactants into turbulent flow can reduce friction drag greatly. A new approach to saving energy in district cooling systems is to use surfactant solution at subzero temperatures as the cooling fluids. However, a serious drawback usually accompanying with the drag reduction is a larger turbulent heat transfer reduction. Therefore, it is of significant importance to study the drag and heat transfer characteristics of the surfactant drag-reducing flow and the corresponding heat transfer enhancement methods for developing efficient district cooling systems. In this paper, experiments were conducted to study the drag-reduction and heat transfer performances of a newly synthesized zwitterionic surfactant solution (Oleyl trimethylaminimide) in a two-dimensional channel. For testing the drag-reduction at subzero temperatures, a 20% ethylene glycol aqueous solution (EG/W) was used as solvent. It was found that the novel zwitterionic surfactant solution showed both drag and heat transfer reduction characteristics, which were affected by concentration and temperature. The maximum drag reduction was 83% at 25 °C for 200 ppm surfactant solution. The effects of addition of NaNO2 to the surfactant solution were also investigated. For enhancing heat transfer of the surfactant drag-reducing flow, a destructive device, named Block, was designed and used in the experiments. The Block device has two contracting-expanding flow passages on both sides respectively with the central part blocked. It was found that the Block device can enhance the heat transfer performance of the novel zwitterionic surfactant solution to some extent while having a very small pressure drop penalty compared with other researcher’s destructive devices.