Effect of surfactants on flow boiling heat transfer and bubble dynamic: an experimental study

Abstract

Compared with pure water, aqueous surfactant solutions of have more outstanding boiling heat transfer performance. However, most of the relevant studies in the literature are limited to saturated pool boiling, while the research on subcooled flow boiling is very scarce. In this study, we experimentally investigated the influence of adding surfactants on the heat transfer performance and bubble dynamics of flow boiling. Under the dual effects of inhibition of bubble coalescence by surfactant and subcooled condensation, it exhibits a special periodic bubble cluster behavior on the wall. The aqueous solution of the surfactant shows a higher boiling heat transfer coefficient than pure water, with the maximum increase reaching 45 %. A new empirical correlation has been developed to quantitatively express the increase in the heat transfer coefficient. Furthermore, the research also found that when the subcooling degree is low, the surfactants will reduce the flow boiling critical heat flux. However, as the subcooling degree increases, this reducing effect will gradually weaken and even reverse into a promoting effect. The results of this study indicate that the aqueous surfactant solutions could be a potentially beneficial alternative to water for better flow boiling heat transfer performances.