Experimental analysis of boiling enhancement from surfactant addition with electric fields

Abstract

This thesis consists of an experimental investigation of the effect of surfactants on the boiling curve of water. Via adsorbtion to the boiling surface, surfactants alter the surface energy interaction during bubble formation at nucleation sites. The surfactants initially enhance the heat transfer coefficient at the onset of nucleate boiling due to higher nucleation density and higher bubble departure frequency. The critical heat flux, on the other hand, generally dropped by nearly 50% in the presence of surfactants. As these surfactants are charged molecules, the application of an electric field was used to increase or decrease adsorption of surfactants on the boiling surface, thereby tuning the level of boiling enhancement during the onset of nucleate boiling and further illustrating the role of surfactants in the boiling process.