(440e) Antifoams in Diesel Fuels: Thin Liquid Film Dynamics and Antifoam Mechanisms

Foaming in diesel fuels is detrimental for many industrial applications. To combat the deleterious effects of foaming, diesel fuel formulations often include additives called antifoams. Existing fuel-antifoam formulations, unfortunately, are inherently ash-containing and may result in negative environmental implications when combusted. Because of this, these ash-containing chemistries are not allowed by some legislations, and hence there is a pressing need to identify alternative antifoam chemistries, yet still offer superior antifoaming characteristics. Accomplishing this goal requires a systematic characterization of foam stabilization and antifoaming mechanisms with different fuel-antifoam chemistries.

Motivated by this goal, here we investigate foaming and antifoam mechanics of diesel fuels, when mixed with two different families of antifoam additives (Organo-modified Silicone and an ashless chemistry) at different antifoam concentrations and droplet size distributions. These ashless antifoams are a potential replacement for ash containing silicones. We utilize a custom experimental technique that allows us to study thin film dynamics and foam stability on a single bubble level, and which correlates to bulk foam behavior. Our results indicate that solutocapillary flows, specifically those caused by evaporation of individual components, are important in stabilizing diesel fuel foams. In addition, these single bubble analyses lead to insights into mechanism of action for foam destabilization and rupture, allowing better understanding of foaming dynamics for each diesel-antifoam combination.