An experimental apparatus for testing biodiesels based on a CFR engine – Setup and validation with different methyl ester blends

A CFR engine was modified and instrumented in order to control operating conditions and to measure engine parameters and in-cylinder pressure diagrams. Aiming at the comparison of different alternative fuels, an experimental procedure was defined, including Cetane Number evaluation and the definition of engine operating quantities in different working points, for fixed levels of compression ratio and injection advance. An investigation was made considering several blends of methyl-esters of rapeseed oil and of a mix of vegetable oils with conventional diesel oil. The defined experimental procedure was applied to assess Cetane Number, engine brake thermal efficiency and exhaust emissions. Results show that the biodiesel content has a positive influence on soot emissions, with strong reduction, while thermal efficiency and NOX emissions are negatively affected, which can be justified taking into account fuel properties and changes in combustion process. As observed outcomes are generally in line with those presented in literature, the facility proved to be a suitable tool for basic investigations on alternative fuels to be used in specific applications.