Abstract
Heat transfer coefficients are known to decrease in a drag-reducing surfactant solution flow. Therefore, it is necessary to develop effective heat transfer enhancement methods for a surfactant solution flow. The objective of this study is to examine the heat transfer enhancement effect when microbubbles are injected into a drag-reducing surfactant solution flow. Previous experimental results have suggested that the effects of microbubble injection are greater as the surfactant concentration is close to the critical micelle concentration (CMC). Therefore, concentrations of the test fluid were set at around 180 ppm or more. The diameter of the microbubble injected into the test fluid was around 70 μm. As a result, the heat transfer coefficient was enhanced by microbubble injection. The heat transfer enhancement effect depends on the air-surfactant solution flow ratio and the microbubble size. That is, an increase in the air-surfactant solution flow ratio or decrease in the microbubble size leads to a greater heat transfer enhancement effect.
