Effects of Fuel Property Changes on Heavy-Duty HCCI Combustion

Molina

Energy Conversion and Management

et al. 2015

154

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.

Section: Introductionmentioning

confidence: 99%

Effects of direct injection timing and blending ratio on RCCI combustion with different low reactivity fuels

Molina

Energy Conversion and Management

et al. 2015

154

“…Thus, when increasing engine load not enough mixing time before the start of combustion is provided. On this regard, Bessonette et al [13] suggested that different in-cylinder reactivity is required for the proper HCCI operation under different operating conditions. Specifically, high cetane fuels are required at low load and a low cetane fuels are needed at medium-high load.…”

Section: Introductionmentioning

confidence: 99%

The role of the in-cylinder gas temperature and oxygen concentration over low load reactivity controlled compression ignition combustion efficiency

Desantes

et al. 2014

Energy

101

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

“…It has been demonstrated its potential to produce virtually no soot or NOx emissions while maintaining high efficiency [1][2] [3], but in return, new challenges regarding combustion control [4] [5] and mechanical engine stress were also identified [6]. Thus, Bessonette et al [7] suggested that different in-cylinder reactivity is required for proper HCCI operation under different operating conditions. In particular, high cetane fuels are required at low load and a low cetane fuels are needed at medium-high load.…”

Section: Homogeneous Charge Compression Ignition (Hcci) Is a Widely Imentioning

confidence: 99%

Effects of low reactivity fuel characteristics and blending ratio on low load RCCI (reactivity controlled compression ignition) performance and emissions in a heavy-duty diesel engine

Molina

et al. 2015

Energy

126

ElsevierBenajes Calvo, JV.; García Martínez, A.;Monsalve Serrano, J. (2015). Effects of low reactivity fuel characteristics and blending ratio on low load RCCI (reactivity controlled compression ignition) performance and emissions in a heavy-duty diesel engine. Energy. 90:1261Energy. 90: -1271Energy. 90: . doi:10.1016Energy. 90: /j.energy.2015.088.Effects of low reactivity fuel characteristics and blending ratio on low load RCCI (reactivity controlled compression ignition) performance and emissions in a heavy-duty diesel engine Energy, Volume 90, October 2015, Pages 1261-1271. http://dx.doi.org/10.1016/j.energy.2015 Jesús Benajes, Santiago Molina, 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 effect of low reactivity fuel characteristics and blending ratio on low load RCCI performance and emissions using four different low reactivity fuels: E10-95, E10-98, E20-95 and E85 (port fuel injected) while 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 tests were carried out at 1200 rev/min and constant CA50 of 5 CAD ATDC. For this purpose, the premixed energy was equal for the different blends and the EGR rate was modified as required, keeping constant the rest of engine settings. In addition, a detailed analysis of air/fuel mixing process has been developed by means of a 1-D spray model.Results suggest that in-cylinder fuel reactivity gradients strongly affect the engine efficiency at low load. Specifically, a reduced reactivity gradient allows an improvement of 4.5% in terms of gross indicated efficiency when the proper blending ratio is used. In addition, EURO VI NOx and soot emission levels are fulfilled with a strong reduction in CO and HC compared with the case of the higher reactivity gradient among the low and high reactivity fuel.