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The aim of this paper is to analyse the main concerns related to on board hydrogen catalytic production of fuel cell electric vehicles, starting from different gaseous and liquid fuels. In particular, limits and potentialities of hydrocarbons and alcohols have been examined, considering steam reforming and partial oxidation reactions with reference to emission and efficiency implications. Preliminary results of an experimental investigation on steam reforming of natural gas and liquid hydrocarbons are reported. Furthermore, a mono-dimensional mathematical model of methane steam reformer based on first order kinetics has been developed to simulate the experimental results.

A chemical and physical characterization of particulate emitted in undiluted exhaust of single cylinder direct injection (D.I.) diesel engine was made by an optical technique. On-line scattering and extinction measurements in the spectral range from 200 to 500nm were carried out in the exhaust ofthe engine operating under steady-state conditions. These measurements provided a useful tool for the comprehension of chemical and physical structure of the particulate. They allowed the evaluation in real time of the size, the concentration and also the optical properties. Preliminary results of size and mass concentration of particulate are presented. A good agreement was observed comparing the results with those obtained by gravimetric measurements, TEM and X-ray diffraction. HIGH EFFICENCY OF DIESEL ENGINES and their ability to burn heavy fuels make them ofgreat interest in the transportation field.

The development of combustion system of a multipurpose utility single cylinder d.i. diesel engine for low emissions is discussed. Engine tests, using two shallow re-entrant combustion bowls, four nozzles with reduction sac volume and different holes diameter and spray angle, have been carried out. Shallow re-entrant bowls with high compression ratio give low smoke emissions. Nozzles with reduced sac volume decrease the hydrocarbon emissions while NOx emissions can be limited operating at more retarded start of combustion.

Improvement of combustion system for low emissions of a single cylinder diesel engine is presented. In particular the effects of spray angle, holes diameter and number, compression ratio and combustion chamber geometry on engine performance and emissions are evaluated. The fluid-dynamic behaviour of combustion system is analyzed by LDA technique. Engine tests have been carried out at two engine speed and at different start of combustion. The particulate matter has been analyzed in terms of soluble organic fraction and dry soot.