Taguchi-Grey relational-based multi-response optimization of the water-in-diesel emulsification process

The use of water-in-diesel emulsion fuel positively influences the performance and emission characteristics of diesel engines. The problem associated with the introduction of such fuel into existing diesel engines is the lack of favorable emulsion qualities, such as a high stability period, nominal heating value, medium density and low kinematic viscosity. The traditional Taguchi method has been applied to determine the optimal condition for single responses only; to overcome this limitation, the Taguchi-Grey relational-based multiresponse optimization method is adopted in the present study to obtain such beneficial emulsion fuel qualities. Experiments are conducted based on the L9 orthogonal array suggested in Taguchi's quality concept, and the output responses are recorded. The emulsification process control parameters viz., surfactant concentration, stirrer speed and water concentration are identified as input parameters. Results show that all the process parameters significantly influence emulsion quality. An optimal parametric setting is determined according to S/N ratio and verified through confirmation experiments. This setting effectively improves emulsion quality. Furthermore, the properties of the W/D emulsion fuel prepared at the optimal parametric setting meet the diesel fuel requirements prescribed by the European standard of automotive fuel requirements (EN 590:2009).