Influence on Diesel Injection Characteristics and Behavior Using Biodiesel Fuels

The aim of this paper is to present an experimental study of the influence of using biodiesel blended fuels on a standard injection system taken from a DI commercial Diesel engine. The effects have been evaluated through injection rate measurements, spray momentum and spray visualization at ambient temperature (non-evaporating condition). These tests have been done using five different injection pressures, from 300 to 1600 bar, and three back pressures: 20, 50 and 80 bar.

It is well known that fuel properties like density or kinematic viscosity are higher in vegetable oils and strongly affect how injection system operates. The tests showed that the use of biodiesel fuels leads to a higher mass flow when the injector is fully open. The spray pattern is also affected, biodiesel penetrates more and the spray is narrower. Some explanations are provided in this paper in order to understand better the injection process when vegetable oils are used.