Conceptual models for partially premixed low-temperature diesel combustion

Musculus, Mark P.; Miles, Paul C.; Pickett, Lyle M.

doi:10.1016/j.pecs.2012.09.001

Cited by 577 publications

(295 citation statements)

References 36 publications

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“…The CO formed in relatively high ф conditions will likely be oxidized along the combustion process; because combustion temperatures are high enough to assure proper CO-CO2 conversion. However, the slower reacting, over-lean mixtures located in the squish region and in the central part of the cylinder, with temperatures lower than 1500 K, will not be properly oxidized; thus, becoming the main source of CO and HC emissions, as reported by Musculus et al [60]. Figure 14 also confirms how the soot formation is concentrated primarily in the zones with ф over 1 and 2 in the inner side of the sprays, as it was expected, close to the bowl walls where combustion develops and temperatures are the highest.…”

Section: Analysis Of Local Conditions Operating With the Gasoline Ppcmentioning

confidence: 95%

Investigation on Multiple Injection Strategies for Gasoline PPC Operation in a Newly Designed 2-Stroke HSDI Compression Ignition Engine

Benajes

Lima

Tribotté

2015

SAE Int. J. Engines

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Partially Premixed Combustion (PPC) of fuels in the gasoline octane range has proven its potential to achieve simultaneous reduction in soot and NOX emissions, combined with high indicated efficiencies; while still retaining proper control over combustion phasing with the injection event, contrary to fully premixed strategies. However, gasoline fuels with high octane number as the commonly available for the public provide a challenge to ensure reliable ignition especially in the low load range, while fuel blends with lower octane numbers present problems for extending the ignition delay in the high load range and avoid the onset of knocking-like combustion. Thus, choosing an appropriate fuel and injection strategy is critical to solve these issues, assuring successful PPC operation in the full engine map.In this framework, the objective of the present investigation consists of evaluating the use of multiple injection strategies for achieving stable PPC operation, attaining low NOX and soot emissions together with high efficiencies. This research was carried out in a singlecylinder DOHC 2-stroke HSDI CI engine using 95 Research Octane Number (RON) gasoline fuel. Three different operating conditions in terms of indicated mean effective pressure (IMEP) and speed were investigated: 3.1 bar IMEP and 1250 rpm, 5.5 bar IMEP and 1500 rpm and 10.4 bar IMEP and 1500 rpm. Parametric variations of injection timings, at different rail pressures and different fuel split between injections were experimentally performed to analyze the effect of the injection strategy over the combustion process, exhaust emissions and efficiency levels.Experimental results confirm how using an appropriate injection strategy helps to achieve stable PPC operation in the selected operating conditions; with competitive combustion stability, lower NOX and soot levels, and moderate CO and HC emissions with combustion efficiency over 96%, compared to Conventional Diesel Combustion (CDC).Finally, a detailed analysis of the local cylinder conditions was performed by means of 3D-CFD simulations in order to provide guidelines for further optimization of the gasoline PPC concept, when using multiple injection strategies in the 2-stroke engine under development.

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Section: Analysis Of Local Conditions Operating With the Gasoline Ppcmentioning

confidence: 95%

Investigation on Multiple Injection Strategies for Gasoline PPC Operation in a Newly Designed 2-Stroke HSDI Compression Ignition Engine

Benajes

Lima

Tribotté

2015

SAE Int. J. Engines

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“…Part of this research effort has been performed by means of optical techniques, which has produced a deep understanding of fundamental processes that have been summarized in conceptual models, such as the ones by Dec [1] or more recently by Musculus et al [2].…”

Section: Introductionmentioning

confidence: 99%

An experimental analysis on the evolution of the transient tip penetration in reacting Diesel sprays

Desantes

Pastor

García-Oliver

et al. 2014

Combustion and Flame

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Schlieren imaging has helped deeply characterize the behavior of diesel spray when injected into an oxygen-free ambient. However, when considering the transient penetration of the reacting spray after autoignition, i.e. the Diesel flame, few studies have been found in literature. Differences among optical setups as well as among experimental conditions have not allowed clear conclusions to be drawn on this issue. Furthermore, soot radiation may have a strong effect on the image quality, which cannot be neglected.The present paper reports an investigation on the transient evolution of Diesel flame based upon schlieren imaging. Experimental conditions have spanned values of injection pressure, ambient temperature and density for typical Diesel engine conditions. An optimized optical setup has been used, which makes it possible to obtain results without soot interference. Based on observations for a long injection event (4 ms Energizing Time), the analysis has resorted to extensive comparison of inert and reacting sprays parameters, which have made it possible to define different phases after autoignition.Shortly after autoignition, axial and radial expansion of the spray have been observed in terms of axial penetration and radial cone angle. After that, during a stabilization phase, the reacting spray penetrates at a similar rate as the inert one. Later, the reacting spray undergoes an acceleration period, where it penetrates at a faster rate than the inert one. Finally, the flame enters a quasi-steady penetration phase, where the ratio of reacting and inert penetration stabilizes at a nearly constant value. The duration of the reacting spray penetration stages shows modifications when varying engine parameters such as air temperature, air density, injection pressure, and nozzle diameter. However, the proportionality between reacting and inert penetration has been observed to depend mainly on temperature, in agreement with observed reductions in entrainment when shifting from inert to reacting conditions.

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“…As it can be seen, the higher maximum local equivalence ratios are obtained for the lowest PER as a result of the higher diesel amount injected in these cases. Even in these conditions, the value of the maximum local equivalence ratio is around φL=2, which confirm the non-formation of soot [44][45] [46]. Moreover, it is interesting to remark how an E85/air ambient enhances the mixing process for the diesel fuel.…”

Section: Soot Emissionsmentioning

confidence: 75%

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

Benajes

Molina

García

et al. 2015

Energy

123

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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.

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Conceptual models for partially premixed low-temperature diesel combustion

Cited by 577 publications

References 36 publications

Investigation on Multiple Injection Strategies for Gasoline PPC Operation in a Newly Designed 2-Stroke HSDI Compression Ignition Engine

Investigation on Multiple Injection Strategies for Gasoline PPC Operation in a Newly Designed 2-Stroke HSDI Compression Ignition Engine

An experimental analysis on the evolution of the transient tip penetration in reacting Diesel sprays

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

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