Drag-reducing and heat transfer characteristics of a novel zwitterionic surfactant solution

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. The surfactant concentration ranged from 50 to 1000 ppm and the temperature was -5 and 25 °C, respectively. 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 due to the dominant action of elongational stress.