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Influence of cetane-detergent additives to diesel fuel with RME content increased to 10% on the parameters of indicator diagrams and rate of heat release in a diesel engine

The proposed publication is the second part of the article „The influence of cetane-detergent additives in diesel fuel increased to 10% of RME content on energy parameters and exhaust gas composition of a diesel engine” and is a cause-effect analysis of the phenomena related to the impact of 3 additive packages used in diesel oil with RME content increased to 10%. In the studies described in the first article, it was found that the first fuel additive package reduces the NOx concentration in a beneficial, though the insignificant way in the exhaust gases only at low engine loads. The second additive package quantitatively influenced the reduction of the NOx concentration in the engine exhaust in a similar way as the first additive. However, the effect of this additive was the more effective (from the point of view of reducing the NOx concentration) the higher the engine load. Because then the engine control switches off the EGR system, and in addition, due to the rising combustion temperatures, the amount of nitrogen oxides formed in the cylinder increases, it was found that the mode of operation of the second additive package is more beneficial than the first package. Due to the fact that the second additive package has been practically too small, it was decided to increase the amount of cetane additive in package 3 by a factor of 2. Thanks to this, the delay of self-ignition (s) for fuel with the third additive package was reduced by as much as 30% compared to the comparative fuel. Reducing s leads to a reduction in the amount of fuel accumulated in the combustion chamber at the time of its self-ignition. This, in turn, leads to the reduction of the maximum kinetic combustion rate ((Qk/)max), lower rate of pressure ((dp/d)max) in the engine cylinder just after the self-ignition of the fuel, lower maximum combustion pressure ((psp)max) and max temperature of combustion ((Tsp)max). Because in the conditions of processes taking place during the combustion of fuel in the engine cylinder, it is the reduction in the combustion temperature that is the main reason for the reduction of the amount of NOx formed, the use of the third additive package, which shortens s the most, is associated with the lowest NOx concentration in the engine exhaust (in comparison to the engine fueled by the comparative fuel). The article analyses the correlation between the number and proportions of additives used in packages 1, 2 and 3, and the parameters of indicator diagrams, as well as parameters of heat release graphs (including the maximum rate of kinetic and diffusion heat release), NOx concentration and smoke opacity. This operation allowed both the determination of the right direction of quantitative and qualitative changes in relation to the value of engine energy parameters and the composition of the exhaust for the engine fuelled by tested additive packages.
Topic: Alternative fuels
Author: Winicjusz STANIK
Co-authors: Jerzy CISEK