Ignition and combustion development for high speed direct injection diesel engines under low temperature cold start conditions

Pastor, Javier; García-Oliver, José M; Ramírez-Hernández, J.G.

doi:10.1016/j.fuel.2011.01.008

Cited by 79 publications

(42 citation statements)

References 23 publications

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“…All the engine tests were developed following a parametrical scheme on a single cylinder engine, in order to attain a better control of the operating conditions [13]. In this work, a single-cylinder, four-stroke, compression ignition research engine, representative of commercial truck engines, has been used.…”

Section: Experimental Set-upmentioning

confidence: 99%

An investigation on RCCI combustion in a heavy duty diesel engine using in-cylinder blending of diesel and gasoline fuels

Benajes

Molina

García

et al. 2014

Applied Thermal Engineering

162

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ElsevierBenajes Calvo, JV.; Molina Alcaide, SA.; García Martínez, A.; Belarte Mañes, E.; Vanvolsem, M. (2014). An investigation on RCCI combustion in a heavy duty diesel engine using in-cylinder blending of diesel and gasoline fuels. Applied Thermal Engineering. 63 (1) AbstractAn experimental and numerical study has been carried out to understand mixing and auto-ignition processes in RCCI combustion conditions, using gasoline and diesel as low and high reactivity fuels, respectively. Three parametrical studies have been developed using a heavy duty compression ignition engine equipped with a direct injector and a port fuel injector, to be able to vary the in-cylinder fuel blending ratio. Besides, a detailed analysis in terms of air/fuel mixing process has also been performed by means of a 1-D spray model. It is found that combustion starts with the auto-ignition of the diesel injection and the air and gasoline entrained. Then, the temperature and pressure raise starts the flame propagation across the lean diesel and gasoline zones of the combustion chamber. As the Diesel/Gasoline fuel ratio is reduced, the ignition delay increases extending the mixing time and the first combustion stage gets lowered while the second one is enhanced. The advance of the diesel injection timing enlarges the mentioned effects over the combustion process. With respect to conventional neat diesel combustion, a slight reduction in terms of NOx and a very important reduction in terms of soot were achieved with the RCCI combustion.

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Section: Experimental Set-upmentioning

confidence: 99%

An investigation on RCCI combustion in a heavy duty diesel engine using in-cylinder blending of diesel and gasoline fuels

Benajes

Molina

García

et al. 2014

Applied Thermal Engineering

162

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“…The values calculated from this expressions are also shown in Figures 2.4 and 2.5. The first part of the penetration is linear mostly due to the transient state of the initial injection rate [32], which is consistent with the results presented in [33], where a triangular injection rate (increasing velocity linearly with time) lead to a linear spray penetration along time. And as concluded in [13], the first part of the penetration (linear) is dominated by the injected fuel, while the second part (square root) is by the entrained air.…”

Section: Spray Penetrationsupporting

confidence: 90%

An experimental study of the effects of fuel properties on diesel spray processes using blends of single-component fuels

Fajardo¹,

Martin²

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Resumen.Estosúltimos años, la tendencia en motores diesel ha sido la de emplear distintos tipos de combustibles para identificar su influencia y comportamiento sobre las emisiones y rendimiento. Dentro de la amplia variedad de combustibles empleados están los llamados combustibles de referencia (PRFs ingl. Primary Reference Fuels), los cuales representan el comportamiento del diesel y la gasolina en lo que respecta a propiedades de encendido, ya que se encuentran en ambos extremos de la escala del número de octano y también poseen números de cetano muy distintos. Una de las desventajas de utilizar gasolina pura o mezclas de diesel-gasolina en motores diesel es el tiempo que toma la mezcla en encender y quemar completamente el combustible. Esto generalmente requiere trabajar con cargas parciales o cargas premezcladas.Para poder aislar los efectos del combustibles sobre los procesos de un chorro y que sea capaz estudiar los parámetros característicos de tiempo de retraso de encendido, longitud de despegue de llama, penetración de líquido y vapor, entre otros, se han realizado distintos experimentos bajo variaciones paramétricas de condiciones de motor diesel. Los ensayos han sido realizados bajo condiciones inertes y reactivas en un motoróptico de dos tiempos y una instalación de alta presión y alta temperatura de flujo continuo a presión constante (CPF ingl. Constant-Pressure Flow ) empleando toberas mono-orificio, con aplicación de diversas técnicaś opticas. Para estudiar la influencia de las propiedades de los combustibles se utilizaron distintos mono-componentes, así como mezclas binarias y un sustituto de diesel conformado por seis componentes, el cual fuel comparado con diesel convencional. Adicionalmente, los resultados han sido contrastados con un modelo unidimensional para ayudar a explicar los valores y tendencias encontrados.Los resultados presentaron una fuerte dependencia de las propiedades de los combustibles en los ensayos realizados bajo condiciones inertes y reactivas. La diferencia entre las propiedades físicas del n-decano y n-hexadecano mostraron una reducción casi lineal sobre la longitud líquida estabilizada hasta aproximadamente un 60 % bajo ciertas condiciones. Adicionalmente, debido a la composición del combustible de sustitución, el n-hexadecano puro demostró tener características de evaporación prácticamente idénticas, probándose a sí mismo como un buen candidato para ser un sustituto mono-componente del diesel convencional. De una manera similar, las propiedades químicas de los PRFs n-heptano e iso-octano también probaron tener influencia sobre el desarrollo del chorro y radiación emitida. Se obtuvieron valores de tiempo de retraso con diferencias de hasta un orden de magnitud entre ambos extremos del rango de las mezclas, así como longitudes de despegue de llama hasta tres veces más largas. La radiación emitida por la incandescencia del hollín presentó las variaciones más altas, ya que algunas condiciones mostraron reducciones de hasta cuatroórdenes de magnitud dentro del rango de mezc...

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“…First, segmentation was performed for every image by calculating a threshold value, which is equal to the minimum digital level in the image plus 15% of the difference between the maximum and the minimum. This percentage was set, based on previous experience, as a compromise to remove light reflected off the liquid spray and the chamber walls without losing much information from the combustion event [31,32]. After segmentation, the flame area is defined as the summation of the number of pixels which belong to the flame (above the threshold).…”

Section: Image Processing Toolsmentioning

confidence: 99%

Impact of Spark Assistance and Multiple Injections on Gasoline PPC Light Load

Benajes¹,

Tormos²,

García³

et al. 2014

SAE Int. J. Engines

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Along the last years, engine researchers are more and more focusing their efforts on the advanced low temperature combustion (LTC) concepts with the aim of achieving the stringent limits of the current emission legislations. In this regard, several studies based on highly premixed combustion concepts such as HCCI has been confirmed as a promising way to decrease drastically the most relevant CI diesel engineout emissions, NOx and soot. However, the major HCCI drawbacks are the narrow load range, bounded by either misfiring (low load, low speed) or hardware limitations (higher load, higher speeds) and the combustion control (cycle-tocylce control and combustion phasing). Although several techniques have been widely investigated in order to overcome these drawbacks, the high chemical reactivity of the diesel fuel remains as the main limitation for the combustion control.The attempts of the researchers to overcome these disadvantages are shifting to the use of fuels with different reactivity. In this sense, gasoline PPC has been able to reduce emissions and improve efficiency simultaneously, but some drawbacks regarding controllability and stability at low load operating conditions still need solution. In this field, previous researches have been demonstrate the multiple injection strategy as an appropriate technique to enhance the combustion stability. However, PPC combustion has been found limited to engine loads higher than 5 bar BMEP when using fuels with octane number greater than 90. In this regard, previous work from the authors showed the capability of the spark plug to provide combustion control in engine loads below this limit even using 98 ON gasoline.The main objective of the present work is to couple the control capability of the spark assistance together with an appropriate mixture distribution by using double injection strategies with the aim of evaluating performance and engine-out emissions at low load PPC range using a high octane number gasoline. For this purpose the optical and metal version of a compression ignition single-cylinder engine, to allow high compression ratio, has been used during the research. A common rail injection system enabling high injection pressures has been utilized to supply the 98 octane number gasoline. An analysis of the incylinder pressure signal derived parameters, hydroxyl radical (OH*) and natural luminosity images acquired from the transparent engine as well as a detailed analysis of the air/fuel mixing process by means of a 1-D in-house developed spray model (DICOM) has been conducted. Results from both analysis methods, suggest the spark assistance as a proper technique to improve the spatial and temporal control over the low load gasoline PPC combustion process. A noticeable increase in the cycle to cycle repeatability (5% versus 15.1% CoV IMEP at 2 bar load) as well as a reduction in the knocking level (20.5 versus 33.6 MW/m 2 at 7 bar load) is observed. In addition, the combination of the spark assistance with the use of the double injection strategy ...

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Ignition and combustion development for high speed direct injection diesel engines under low temperature cold start conditions

Cited by 79 publications

References 23 publications

An investigation on RCCI combustion in a heavy duty diesel engine using in-cylinder blending of diesel and gasoline fuels

An investigation on RCCI combustion in a heavy duty diesel engine using in-cylinder blending of diesel and gasoline fuels

An experimental study of the effects of fuel properties on diesel spray processes using blends of single-component fuels

Impact of Spark Assistance and Multiple Injections on Gasoline PPC Light Load

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