Experimental Study of Biodiesel Blends' Effects on Diesel Injection Processes

This paper presents an experimental comparison of three biodiesel blends on DI diesel injection process using a standard injection system derived from a 4-stroke DI commercial diesel engine. Specifically, this work relies on several experiments carried out over a commercial diesel fuel, with 5.75% of rape methyl ester called B5, another with 30% of RME (1330), and a pure rape methyl ester fuel (called RME). Analyses on injection rate shape, spray force, spray tip penetration, and cone angle in nonevaporative conditions have been performed and studied to compare the effect of those different fuels over the injection process. A better understanding of injection process will be useful to achieve a better comprehension of mixing process which determines combustion and emissions in a compression ignition engine. It is well-known that fuel properties like density or kinematic viscosity are higher in vegetable oils and strongly affect how injection system operates. An increase in the hydraulic delay and a higher mass flow rate have been observed in injection rate measurements, when using biodiesel; macrovisualization showed that the biodiesel fuel has slightly longer penetration and narrower cone angle that leads to smaller spray volumes.