Experimental study on injection characteristics of diesel and biodiesel fuel blends with common rail injection system

Abstract

The limited fossil fuel reserves and the ecological aspects encourage the scientists to conduct the research on a new alternative renewable energy resource. In the European Union diesel – powered transport machines produce approximately 21 % of the total emissions causing the greenhouse effect and this tendency is in a constant progress. The transport and agriculture sectors are among the largest consumers of the mineral fuels contributing to the environment pollution. The EU directives promote the production and consumption of biofuels, therefore, the member-states have committed to the promotion of biofuels and other renewable fuels instead of using fossil-origin gasoline or diesel fuel. The article presents the experimental test results of the fuel injection processes of diesel and biodiesel fuel blends, when using high-pressure common rail injection system. The injection characteristics were determined using the injection rate measuring instrumentation. The aim of the study was to get insight in the changing behaviour of the injection rate, amount of the fuel injected per cycle, actual injection delay and the duration of the process over the whole variation range of both the injection pressure and the energizing time. The test results showed that the maximum injection rate of diesel – biodiesel fuel blends was lower than that of a neat diesel fuel case. It was observed that density and viscosity of the fuel have a significant effect on the form of injection characteristics. The injection process has significant influence on the combustible mixture formation inside the cylinder of a diesel engine, auto-ignition, combustion, and exhaust emissions.