Heat transfer from a small heater to a falling liquid film

Experimental investigation of convective heat transfer from two heaters of height 6.5 mm and 13 mm to a freely falling film of a 25%-solution of ethyl alcohol in water is carried out. The Reynolds number of the film varied from 14 to 106. The instability and formation of a dry patch on the lower part of the heater wag observed for the 13 mm-high heater at the heat flux of more than 5 W/cm². For the 6.5 mm-high heater such an instability was not observed even for heat fluxes up to 14 W/cm².