Abstract
It is known that small quantities of surfactant additives can greatly reduce the friction factors during the flow of a heat transfer medium. This is because the generation of turbulent vortexes is suppressed by the formation of rod-like micelles, and the flow remains laminar in the larger Reynolds number range. However, the values of the heat transfer coefficients decrease during flow laminarization ; this would result in a requirement for heat exchangers with a larger heat transfer area. The research objective is to examine heat transfer enhancement effects by air injection. This paper presents an experimental investigation on the heat transfer characteristics in an air-surfactant solution two-phase flow through a vertical tube. Heat transfer coefficients were enhanced drastically with the injection of air into a drag-reducing surfactant solution flow. The enhancement rates were much larger for the surfactant solution than for water. However, heat transfer coefficients were smaller for an air-surfactant solution flow than for an air-water flow due to the drag-reducing effects. As the gas quality increased, the heat transfer coefficients for air-surfactant solution flow approached those for air-water flow.
