Heat transfer in pool boiling with surfactants

Abstract EN

Boiling with surfactant is important in many key industrial applications such as the petrochemical processing, refining, refrigeration, hygiene and personal care, pharmaceutical, and food processing, among others.

The aims of this study are experimental determination of the heat transfer coefficient with and without the addition of surfactants to pure water and quantify the effects of surfactant concentration, ionic nature, its ethoxylation, and molecular weight on the nucleate boiling performance of water on vertical cylindrical heater.

Several different surfactants were employed : [SDS (Sodium Dodecyl Sulfate), SLES (Sodium Lauryl Ether Sulfate) (anionic) ] and [Triton X-100 (Octylphenol Ethoxylate) (nonionic)], they have different molecular weights, ionic nature and number of ethylene oxide EO groups attached to its polar head.

The boiling results show that with the addition of small amounts of surfactants, the saturated nucleate pool boiling heat transfer coefficient of water is found to be altered due to reduction in the surface tension and this enhances the heat transfer.

The enhancement in nucleate pool boiling depends upon wall heat flux (or temperature difference), concentration of surfactant, ionic nature, molecular weight and number of (EO) group.

The heat transfer coefficient is found to increase by as much as (81.9 %) over that for pure water for SDS solutions while (53 %) for SLES and (45 %) for Triton X-100 at CMC (critical micelle concentration).

The enhancement increases with concentration and the enhanced solutions are found to be with C ≤ CMC.

The optimum enhancement is at or near the CMC of surfactants.

However, the maximum heat transfer enhancement is in the order of SDS > SLES > Triton X-100, this is also, in the reverse order of their molecular weights and number of (EO) groups.