Fluid flow and heat transfer on a falling liquid film with surfactant from a heated vertical surface

Abstract

The addition of surface active agent to a failing liquid film affects the flow characteristics of the falling film. In this study, the flow and heat transfer characteristics for a failing liquid film have been investigated by addition of the surfactant. The failing liquid film was formed on a vertical flat plate. Contact angle of a liquid droplet above a plate surface can be substantially reduced with an increase in the surfactant concentration. The results obtained indicate that not only the wetted area of falling liquid film is increased but also the film thickness is decreased as the surfactant concentration is increased. It is also found that heat transfer rate is significantly increased while the heat transfer coefficient is almost constant value with an increase in the surfactant concentration at a given mass flow rate.