Zinc oxide incorporated water-in-diesel emulsion fuel: Formulation, particle size measurement, and emission characteristics assessment

The use of W/D emulsion fuel has a positive influence on the performance and emission characteristics of diesel engines, especially on NOx and PM emissions. The prolonged ignition delay of W/D emulsion fuel resulting in rough engine operation is a critical factor that has to be focused on in emulsion fuel studies. ZnO, a metal-based nanoparticle that can act as a catalyst for chemical reactions during combustion process, is adopted in the present study in an attempt to shorten the ignition delay. The problems associated with nanofluid synthesis are agglomeration of nanoparticles and measurement of particle size in base fluid. The present study focuses on the previously-mentioned issues with experiments conducted in two phases. In the first phase, ZnO nanoparticles with mass fraction of 50 ppm and 100 ppm are incorporated in 10W/D emulsion fuel and stabilized using suitable surfactant and its physiochemical properties measured. To measure the ZnO particle size in emulsion fuel, milky form of ZnO incorporated in W/D emulsion fuel is turned into transparent form using DME as a solvent and UV-visible absorption spectroscopy analysis is performed. From the results obtained, it is noted that the properties of 10W/D emulsion fuel meet the standard diesel fuel properties requirement and the incorporation of nanoparticles change the fuel properties marginally. In addition, ZnO particles size in emulsion fuel is confirmed to be at nanolevel. In the second phase, IDP and emission characteristics are studied for 50ZnO10W/D and 100ZnO10W/D, and compared with BD and 10W/D. It is observed that ZnO incorporated W/D emulsion fuel blends have a shorter IDP and lesser emission levels over BD and 10W/D.