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Among the new low temperature combustion modes, Reactivity-Controlled Compression Ignition (RCCI) offers a low NOx-soot trade off (keeping a relatively high engine efficiency). Also, RCCI permits the introduction of a renewable fuel with a lower CO2 direct emission such as short-chains alcohols. For this work, methanol and diesel fuel were used as low and high reactivity fuels, respectively. A 1.3 L single-cylinder engine, with a cylinder volume usual in medium- and heavy-duty truck and bus engines, was used in this work. The engine was operated at an engine speed of 1600 rpm and 25% load (representing one of the 13-mode test on medium duty trucks), which results in an indicated mean effective pressure of 5.2 bar. The effects of methanol substitution ratio (MSR) at 20 and 35% on performance and pollutant emissions was investigated and compared to conventional diesel combustion (CDC).

In order to reduce the pollutant emissions (NOx and PM) of diesel engines, the addition of small gaseous fuel amounts or dual mode operation have been proved as potential techniques. This paper is focused on a detailed characterization of the particles emitted from a single cylinder diesel engine when part of the diesel fuel (5 to 20% by energy) is replaced by a gaseous fuel (producer gas, mainly composed by H2, CO, CH4 and inert compounds) coming from biomass steam gasification. The engine was run at constant speed and torque and different EGR rates. Particle samples were collected by means of fiber glass filters placed in a dilution mini-tunnel. Simultaneously, during tests, part of the exhaust gas was conducted to an SMPS to determine the particle size distribution.