Alexander Santamaría

Chemical Characteristics of the Soot Produced in a High-Speed Direct Injection Engine Operated with Diesel/Biodiesel Blends

The aim of this work is to study the influence of the molecular structure of fatty acid esters present in biodiesel and their blends with diesel on the chemical characteristics of the emitted particulate matter. Biodiesel produced from palm oil, jatropha, castor oil and sachainchi was blended at 5% and 20% by volume with diesel. These fuels were used for the operation of a four-cylinder direct injection automotive diesel engine. The equivalent ratio was kept between 0.36 and 0.40, and the engine was operated at the point of minimum air–fuel ratio and maximum smoke opacity. The amount of particulate matter emitted was evaluated by opacity index. A marked reduction in soot formation was observed when the concentration of unsaturated methyl esters in the fuel was at low concentrations. This was accompanied by a reduction of the aliphatic carbon content in the particulate matter.

Effect of early stages of coal oxidation on its reaction with elemental sulphur

Abstract The present research shows how mild oxidation of coal mostly affects the evolution of H 2 S produced in the reaction of coal with elemental sulphur. Coal samples oxidized at 30, 50, 80 and 150°C were reacted with sulphur in a temperature-programmed reactor. The H 2 S produced in the reaction is very sensitive to the initial stage of the oxidation of coal. The strongest reduction in the amount of H 2 S evolved was observed in the samples oxidized at 30°C. This temperature is lower than the one found in most coal storage places. The reaction with elemental sulphur could be used to monitor the initial stages of coal oxidation, which otherwise would be difficult to follow by conventional analytical methods.