Application of binary mixed surfactant additives in jet impingement cooling of a hot steel plate

The current research aims at investigating role of three different types of surfactants and their binary mixtures in producing high cooling rate during jet impingement on a hot steel plate (100 mm × 100 mm × 6 mm) having initial surface temperature above 900 °C. The surfactants used are Sodium dodecyl sulphate (anionic), cetyltrimethylammonium bromide (cationic) and Polysorbate 20 (Tween 20, non-ionic). The surface tension values of the surfactants and their mixed systems have been measured and it has been observed that the binary mixtures at specific compositions show lower surface tension compared to the pure ones mainly due to synergism. The cooling results reveal that the mixture of cationic and non-ionic surfactants produces the highest cooling rate amongst all the systems. The maximum cooling rate achieved is 182 °C/s for the composition of 25 vol% CTAB and 75 vol% Tween 20 and it is 67% more than that of pure water, 23% more compared to pure CTAB and and 7.7% more than that of pure Tween 20. Thus it can be seen that ultrafast cooling of a 6 mm thick steel plate can be achieved by using optimized concentrations of mixed surfactant additives and this leads to improvement of quality of steel produced.