Effect of Surfactant Molecular Structure on Turbulent Drag Reduction.

Drag reduction and degradation of nonionic surfactant solutions with organic acid in turbulent pipe flow

“…At the solution temperature T ' 20 C, both the maximum drag reduction ratio and the critical Reynolds number become larger due to the addition of salicylic acid. At the lower temperature T ' 10 C, the drag-reducing performance becomes better due to the addition of salicylic acid, in which the degree of the improvement is smaller than that of T ' 20 C. Usui et al [39] reported that the improvement of dragreducing performance due to the addition of NaSal to the ODMAO solution could be obtained at the solution temperature of 25°C, not at 10 and 40°C. In order to improve the drag-reducing performance of ODMAO solutions in the relatively low-temperature region, therefore, the addition of the salicylic acid is superior to that of NaSal.…”

“…At C ¼ 100 ppm and T ' 20 C, the mixture of the ODMAO solution and the salicylic acid with the molar ratio n ¼ 0:2 shows the best drag-reducing ability tested here. Usui et al [39] considered that the negatively-charged counterion encourages the formation of micelles since the amineoxide type surfactant is very weakly positively-charged in water, so that the performance of the drag reduction could be enhanced due to the addition of sodium salicylate (NaSal) as a counterion to the ODMAO solution. The same mechanism can elucidate the present measurements obtained here, but the reason behind the difference between the kinds of organic acids remains unknown at this moment.…”

“…For the typical dragreducing nonionic surfactant (SPE95285, AKZO-Nobel Chemicals, [15][16][17]) which consists of ethoxylated unsaturated fatty alcohols (mainly oleyl alcohol) and the other of ethoxylated unsaturated fatty acid ethanolamides, where the main component of the fatty acids is oleic acid, the rheological property [18], the heat transfer reduction [2], the diameter effect [11], and the temporary degradation and recovery [12] have been clarified so far. Usui et al [41,39] reported the drag reduction of another kind of the nonionic surfactant (Aromox, LION AKZO Co., Ltd.), which mainly consisted of oleyldimethylamine oxide (ODMAO). Recently, Tamano et al [34,35] and Cai et al [6] clarified the fundamental properties of the drag reduction such as the effects of concentration and temperature of ODMAO solutions.…”

“…To overcome the degradation of nonionic surfactant solution, we propose the addition of organic acids such as the salicylic and cuminic acids to the nonionic surfactant (ODMAO) solution with the small molar ratio. This is motivated by the leading study of Usui et al [41,39], who showed the effectiveness of the mixture of the nonionic surfactant solution and the sodium salicylate as drag-reducing additives, in which the available data were restricted and the degradation property remained an open question. The studies on the drag-reducing ability of the mixture of the amineoxide nonionic and betaine zwitterion surfactants have been also reported [3,7].…”

Flow Properties and Heat Transfer of Drag-Reducing Surfactant Solutions

“…However, it was found that the solution lost its solubility in water at temperatures lower than 7 °C, and some ions dissolved in tap water affected the drag reduction caused by CTAC. Therefore, screening tests of surfactants had been conducted (Ohlendorf et al, 1986;Chou et al, 1989;Usui et al, 1998). At the present, oreyl-bishydroxyethyl-methyl-ammonium 3 Cl -) was also selected as a drag-reducing surfactant for higher-temperature use, and a surfactant having an alkyl group carbon number of 22 shows effective drag reduction even over 100 °C (Chou et al, 1989 et al (2000) measured the flow characteristics of a drag-reducing surfactant by using particle tracer velocimetry (PTV) to study the mechanism of drag reduction.…”