In order to explore the mechanism of microbubble emission boiling with high heat transfer performance

numerical simulations were conducted for the velocity field around a single film on the heating surface with the software of FLUENT

and then compared with experimental results. Experimental results indicate that there exists the collapse of film on the heating surface as for water when microbubble emission boiling occurs

and the increase of subcooling and wall superheat would enhance the collapse of film. However

as for ethanol

microbubble emission boiling hardly occurs. Simulation results indicate that there exists marangoni convection around the film under subcooled condition. Moreover

increase of subcooling and surface superheat could enhance marangoni convection around film of water. However

marangoni convection is rather weak near the film of ethanol. Therefore

the disturbance caused by strong marangoni convection near the film at the interface of air and liquid may lead to the collapse of film. This may be one of the reasons triggering microbubble emission boiling.