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The present paper is focused on the application of the Low Temperature Combustion (LTC) systems to modern diesel engines. Aim of the work was to assess the possibility to optimize LTC systems performances in terms of both engine efficiency and pollutant emissions. In particular, the results of a study of the effects of highly cooled Exhaust Gas Recirculation (EGR) on a diesel engine running at LTC condition, will be presented and discussed. The engine employed for the experimental activity was a FIAT JTD 4 cylinder CR diesel engine, EURO 4 version. The EGR layout was modified with respect to the production one, in order to obtain lower temperatures of the recirculated exhaust gases. The performed tests evidence the advantages offered by the strong EGR cooling (and so the lower intake air temperature) in reducing NOx emissions, leaving very low Soot emissions, typical of premixed low temperature combustion.

Aim of the present paper was an evaluation of the importance of some engine parameters (intake gas flow and injection parameters) on the approach of Premixed Low Temperature Combustion (PLTC) conditions with the same efficiency of a conventional diesel cycle and ultra-low pollutant emissions. The results have demonstrated that the control of PLTC mode is very difficult and the engine parameters play a critical role on the exhaust pollutant emissions, indicating that further massive research activities are needed to reach reliable practical applications.

This paper reports some results on the emission performance of a CR DI diesel engine burning five model diesel fuels. The fuels were prepared by Agip Petroli S.p.A within the PNRA research program, sponsored by Italian Ministry of Environment and were a base fuel, a synthetic fuel and three oxygenated fuels. The engine employed in the tests was a prototype derived from Fiat M724 1910 cc, installed on Fiat Group class C Cars (1350 kg of mass). The prototype complies with EURO3 regulations. Two test points representative of two zones of ECE15+EUDC test cycle were chosen. Thermodynamic variables, emissions and injection systems parameters were recorded. Tests show the further potential of advanced fuels, obtained by blends of reformulated and oxygenated components, in reducing pollutants emissions.