Heat Transfer in Pool Boiling with Surfactants
Engineering and Technology Journal,
2010, Volume 28, Issue 17, Pages 5421-5439
AbstractBoiling 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.
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