ElsevierBenajes Calvo, JV.; García Martínez, A.; Monsalve Serrano, J. (2015). Effects of direct injection timing and blending ratio on RCCI combustion with different low reactivity fuels. Energy Conversion and Management. 99:193-209. doi:10.1016/j.enconman.2015.04.046. Effects of Direct injection timing and Blending Ratio on RCCI combustion with different Low Reactivity FuelsEnergy Conversion and Management, Volume 99, 2015, Pages 193-209. http://dx.doi.org/10.1016/j.enconman.2015 AbstractThis work investigates the effects of the direct injection timing and blending ratio on RCCI performance and engine-out emissions at different engine loads using four low reactivity fuels: E10-95, E10-98, E20-95 and E85 (port fuel injected) and keeping constant the same high reactivity fuel: diesel B7 (direct injected). The experiments were conducted using a heavy-duty single-cylinder research diesel engine adapted for dual-fuel operation. All the tests were carried out at 1200 rpm. To assess the blending ratio effect, the total energy delivered to the cylinder coming from the low reactivity fuel was kept constant for the different fuel blends investigated by adjusting the low reactivity fuel mass as required in each case. In addition, a detailed analysis of the air/fuel mixing process has been developed by means of a 1-D in-house developed spray model.Results suggest that notable higher diesel amount is required to achieve a stable combustion using E85. This fact leads to higher NOx levels and unacceptable ringing intensity. By contrast, EURO VI NOx and soot levels are fulfilled with E20-95, E10-98 and E10-95. Finally, the higher reactivity of E10-95 results in a significant reduction in CO and HC emissions, mainly at low load.

Achieving clean and efficient engine operation up to full load by combining optimized RCCI and dual-fuel diesel-gasoline combustion strategies. Energy Conversion and Management.

Several studies carried out with the aim of improving the RCCI concept in terms of thermal efficiency conclude that the main cause of the reduced efficiency at light loads is the reduced combustion efficiency. The present study used both a 3D computational model and engine experiments to explore the effect of the oxygen concentration and intake temperature on RCCI combustion efficiency at light load. The experiments were conducted using a single-cylinder heavy-duty research diesel engine adapted for dual fuel operation.Results suggest that it is possible to achieve an improvement of around 1.5% in the combustion efficiency with both strategies studied; the combined effect of intake temperature and in-cylinder fuel blending as well as the combined effect of oxygen concentration and incylinder fuel blending (ICFB). In addition, the direct comparison of both strategies suggests that the combustion losses trend is mainly associated to the in-cylinder equivalence ratio stratification, which is determined by the diesel to gasoline ratio in the blend since the injection timing is kept constant for all the tests. Moreover, the combined effect of the intake temperature and ICFB promotes a slight improvement in the combustion losses over the combined effect of the oxygen concentration and ICFB. KEYWORDS

Recent emission legislation in the marine sector has emphasized the need to reduce nitrogen oxides (NO x) emissions as well as sulphur emissions. Certain special sea areas, regulated by the MARPOL Convention, are provided with a higher level of protection due to their oceanographical and ecological conditions.

ElsevierBenajes Calvo, JV.; Pastor Soriano, JV.; García Martínez, A.;. The potential of RCCI concept to meet EURO VI NOx limitation and ultra-low soot emissions in a heavy-duty engine over the whole engine map. Fuel. 159:952-961. doi:10.1016Fuel. 159:952-961. doi:10. /j.fuel.2015.064.The potential of RCCI concept to meet EURO VI NOx limitation and ultra-low soot emissions in a heavy-duty engine over the whole engine map Fuel, Volume 159, 1 November 2015, Pages 952-961. http://dx.doi.org/10.1016/j.fuel.2015 Jesús Benajes, José V. Pastor, Antonio García* and Javier Monsalve-Serrano CMT -Motores Térmicos, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain (*) Corresponding author: angarma8@mot.upv.es (Antonio García Martínez) AbstractThis work investigates the potential of RCCI concept to achieve ultra-low NOx and soot emissions over a wide range of engine speed and loads. For this purpose, a detailed experimental methodology has been defined and applied in a heavy-duty single-cylinder engine fueled with diesel and gasoline. In addition, to assess the influence of the engine compression ratio on RCCI capabilities two different compression ratios, 14.4:1 and 11:1, have been tested.Results suggest that a low compression ratio allows to fulfill all the self-imposed constraints (maximum cylinder pressure rise rate of 25 bar/CAD, NOx< 0.4 g/kWh and soot*< 0.01 g/kWh) from idle to full load and engine speeds from 900 to 1800 rpm. However, the use of higher compression ratio requires a delayed injection strategy to avoid excessive knocking levels, which results in unacceptable soot emissions at loads higher than 50%, even when gasoline fractions around 90% are used.