Experimental studies of water-in-diesel emulsions in electric fields

M. Kraut*, P. Kopp, MAHLE Filtersysteme Austria GmbH, R. Woschitz, Graz University, Austria; E.D.L. Böndel, MAHLE Industriefiltration GmbH; P. Ripperger, Kaiserslautern University; B. Renz, MAHLE Filtersysteme GmbH, Germany

Free water can be found in fuel supply systems of diesel engines due to different reasons. Possible ways of water entering the system are for example a disadvantageous mounting of the fuel tank ventilation valve and its exposure to splash water, inadequate care regarding the storage of the fuel by the fuel providers or the condensation of humid air in the fuel tank due to temperature differences. In the fuel supply system the free water and the diesel undergo multiple circulations passing states of low and high system pressure. At this spots energy is induced into both fluids and therefore a stable water-in-diesel emulsion is generated. The presence of free water has a detrimental impact on the fuel supply components. As a consequence corrosion is induced, reduced fuel lubricity causes wear, cavitation damages can be found and the growth of microorganisms leads to covered system parts. Hence it is indispensable to efficiently protect the fuel supply system components by separating the water phase from the diesel fuel. This liquid-liquid separation process can be realized with filter elements arranged in two steps. Coalescer fibers accomplish the merge of the dispersed water droplets and after that a hydrophobic material layer is responsible for final water separation.

Within this work an alternative possibility of realizing accelerated droplet-droplet coalescence is examined. The capability of the physical principle of electrocoalescence to induce coalescence of dispersed water droplets surrounded by a coherent diesel phase under the impact of an applied electric field is surveyed. The motivation for investigating a different method to affect droplet-droplet coalescence is to receive a constant coalescing performance over the lifetime of the coalescer that is fairly independent of the fuel quality. The main objective is to experimentally derive the optimum parameter configuration of the electric field which causes the maximum increase of droplet size distribution within shortest period of time. ...

Session: L18 - Fuel Filtration II - Water Separation
Day: 13 October 2016
Time: 13:00 - 14:15 h

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