Thermal imaging study of falling liquid films

The characteristics of heated/cooled liquid films flowing over a vertical solid plate were experimentally investigated with a highly sensitive infrared camera,Therma CAM ? SC3000(FLIR Systems,Inc.,Portland,OR).For different heating conditions,the temperature profile of the falling liquid film over a heated/cooled solid plate and the effect of heating temperature difference on the liquid distribution were determined.By using the infrared camera,the film width and the interfacial transfer area could be conveniently obtained.It was found that the transverse temperature gradient was much larger than that in the streamwise direction,resulting in significant Marangoni effect that drove the liquid particles from hot(low surface tension) to cold points(high surface tension),inducing novel shrinkage/expansion of the heated/cooled film.The lateral Marangoni effect could therefore strongly affect the interfacial area and thus the transfer process of falling liquid films.