(372q) Separation of Dispersed Water from ULSD Using a Wire Mesh Electrowet Coalescer

Dispersed water drops in diesel fuel can cause undesirable emulsions, acting as a contaminant and can diminish the lifetime and performance of diesel engines. Therefore, separating dispersed water from diesel fuel is crucial and is of high importance. However, existing separation methods pose efficiency limitations as well as environmental and safety challenges. This work presents the performance of a compact electrical coalescer, in coalescing fine dispersed water drops in Ultra Low Sulfur Diesel (ULSD) to from larger drops that are easily separated using gravity settling. The coalescer is comprised of stainless-steel mesh electrodes separated at a relatively close distance from each other to benefit from electrode surface coalescence enhanced by electrowetting. The main objectives of this work were to select the most appropriate operating and geometrical parameters for optimum results. Laboratory tests based on a 2ⁿ factorial design to determine the variables that have the most significant effect on the coalescence and separation performance, as well as finding the optimum conditions. The variables considered were voltage, face velocity, mesh size, and electrode gap distance, while water separation efficiency and average water drop size were the response variables. The proof of concept of the wire mesh electrowet coalescer (EWC) was conducted and showed the EWC could enlarge drops from 30 micron to about 2 mm and required minimal energy to perform. The EWC was also able to achieve a maximum of 91% separation efficiency at the the optimum conditions;150 V, 0.5mm gap distance and a 2cm/min face velocity. Having a smaller pore inlet mesh and larger pore outer mesh showed better performance.