FLUID MOTION AND HEAT TRANSMISSION IN A HORIZONTAL LIQUID-LASER HEATED LOCALLY FROM FREE-SURFACE

Heat transfer from a heated wire and a heated vertical plate, located just below a liquid surface, was studied experimentally. The curve rep resenting the heat transfer coefficient as a function of the temperatu re difference between the heaters and a cooled tray could be divided i nto four parts. The range of each part depended strongly upon the size of the heaters, the depth of the tray and the liquid properties. The mechanism of heat transfer from the heaters in each part was discussed . The following observations were made. In the first part, where the t emperature difference was the smallest, convective heat transfer was o bscured by conduction. The heat transfer was mainly due to natural con vection in the second part, and was mainly due to Marangoni convection in the fourth part. The third part could be considered as a transitio n regime. Furthermore, it was found that the transition was suppressed by the meniscus of the liquid surface which was in contact with the h eaters.