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Methyl esters obtained from the most interesting Spanish oleaginous crops for energy use -sunflower and cynara cardunculus- were both used as diesel fuels in this work, pure and in 25% blends with a reference commercial fuel which was also used pure. A stationary engine test bed, together with the appropriate instrumentation for chemical and morphological analysis, allowed to evaluate the effect of these fuels on the engine emissions, particularly in the main particulate matter characteristics, such as soluble organic fraction, origin of adsorbed hydrocarbons, sulphate content, particle number per unit filter surface, and mean particle diameter. Both the consideration of the main thermochemical properties of the tested fuels and the computations of a chemical equilibrium model were helpful for the analysis of the experimental results.

With the objective of optimising the measurement procedure, the influence of different operating parameters of a certification-like dilution mini-tunnel, such as the dilution ratio and the filtering temperature, is firstly presented in this paper. By means of an environmental chamber, both blank and charged filters were subjected to a range of different temperature and humidity conditions, as well as to different conditioning time periods. In all cases the weighted filters from the mentioned tests were subjected to a soxhlet extraction method, which permitted the chemical analysis of both the soluble organic fraction by gas chromatography and mass spectrometry, and the insoluble one by high performance liquid chromatography (HPLC) and infrared spectrography. Also the contribution of fuel and lubricant to the particulate matter was determined. All this information was related to the mini-tunnel operating parameters and to the ambient conditions.