Enhanced boiling heat transfer by surfactant additives

Small amount of surfactants in aqueous solution have been known to enhance the rate of nucleate boiling heat transfer of water significantly. However, the mechanism of this enhancement is still not clear. In this work, boiling incipience and vapor bubble growth dynamics of aqueous surfactant solutions of sodium lauryl sulfate at identified sites were studied in a pool boiling apparatus with tubular heater by determining the incipient superheat and by high speed photography. Fundamental information about the effects of surfactant additive on incipient superheat, bubble period, waiting period, growth period, and bubble departure size were obtained. Among these, incipient superheat and bubble waiting period are explained with good success by taking into consideration of surface tension depression and contact angle variation in Hsu's (1962) theory.