Abstract
We have carried out measurement of velocity and temperature for warm water containing cool immiscible droplets of hydrofluoroether in a vertical transparent duct. The hydrofluoroether has low global warming potential and zero ozone-depletion potential, which is a major advantage when applying to direct-contact heat exchanger. The droplets descend in the water due to the high specific weight. A particle tracking velocimetry method is applied to obtain the velocity field. A planar laser-induced fluorescence method is applied to measure the temperature distribution. It is found that the temperature decreases noticeably in the wake flow region of the descending droplets. This shows that the heat transfer is enhanced by the wake flow.
