Heat transfer enhancement in turbulent drag reducing surfactant solutions by agitated heat exchangers

In this study, three different rotating agitators were installed inside the inner tube of a concentric tube heat exchanger to enhance heat transfer in a surfactant drag reducing solution. An earlier mathematical model for heat transfer in scraped surface heat exchangers was adapted for this application so that the effectiveness of agitators with different geometries could be compared quantitatively. In addition, an enhancement efficiency factor was defined to compare power efficiency with previous methods. It was found that agitation can increase the effective inner heat transfer coefficient to exceed that of pure water; heat transfer reduction compared to water was reduced from 60% to −20%. In addition, the enhancement can be more energy-efficient than that of previously studied static mixers.