Potential of Thermal Stratification and Combustion Retard for Reducing Pressure-Rise Rates in HCCI Engines, Based on Multi-Zone Modeling and Experiments

Sjöberg, Magnus; Dec, John E.; Cernansky, Nicholas P.

doi:10.4271/2005-01-0113

Cited by 207 publications

(97 citation statements)

References 32 publications

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“…The explanation to the stratification was found in the in high area to volume ratio in combination with slow gas flow inside the bowl resulting in a heater effect. The strong effects of temperature stratification on HCCI combustion rate with the potential of increasing the maximum load have also been studied by other researchers like Sankaran et al [ 8] and Sjöberg et al [ 9].…”

Section: Prior Workmentioning

confidence: 83%

Study on Combustion Chamber Geometry Effects in an HCCI Engine Using High-Speed Cycle-Resolved Chemiluminescence Imaging

Vressner¹,

Hultqvist²,

Johansson³

2007

SAE Technical Paper Series

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The aim of this study is to see how geometry generated turbulence affects the Rate of Heat Release (ROHR) in an HCCI engine. HCCI combustion is limited in load due to high peak pressures and too fast combustion. If the speed of combustion can be decreased the load range can be extended. Therefore two different combustion chamber geometries were investigated, one with a disc shape and one with a square bowl in piston. The later one provokes squish-generated gas flow into the bowl causing turbulence. The disc shaped combustion chamber was used as a reference case. Combustion duration and ROHR were studied using heat release analysis. A Scania D12 Diesel engine, converted to port injected HCCI with ethanol was used for the experiments. An engine speed of 1200 rpm was applied throughout the tests. The effect of air/fuel ratio and combustion phasing was also studied. The behavior of the heat release was correlated with high speed chemiluminescence imaging for both combustion chamber geometries. Optical access was enabled from beneath by a quartz piston and a 45 degree mirror. It was found that the square bowl in piston generates higher turbulence levels resulting in half the ROHR and twice as long combustion duration as the disc shaped combustion chamber. By using a resolution of 3 images per CAD, the fast gas movements during the entire HCCI combustion process could be studied inside the bowl.

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Section: Prior Workmentioning

confidence: 83%

Study on Combustion Chamber Geometry Effects in an HCCI Engine Using High-Speed Cycle-Resolved Chemiluminescence Imaging

Vressner¹,

Hultqvist²,

Johansson³

2007

SAE Technical Paper Series

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“…HCCI yanmasının önemli bir karakteristiği silindir içerisinde neredeyse aynı anda meydana gelen kendiliğinden tutuşma nedeniyle çok hızlı bir yanmanın meydana gelmesidir. Literatürde HCCI motorlar üzerine yapılmış birçok çalışma bulunmaktadır [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. HCCI motorlarda katalitik dönüştürücülere gerek olmaksızın çok düşük NOx emisyonlarının meydana geldiği görülmektedir.…”

Section: Gi̇ri̇ş (Introduction)unclassified

Homojen Karışımlı Sıkıştırma Ateşlemeli (HCCI) Bir Motorun Tek Bölgeli Modelleme Yöntemi Kullanılarak Analizi

Yaşar¹

2016

SAUFenBilDer

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ÖZHCCI motorların modellenmesinde sıfır-boyutlu modeller yaygın olarak kullanılmaktadır. Bu modeller tek veya çok bölge içerebilirler. Bununla birlikte, en basit yaklaşım yanmış ve yanmamış gazı içeren tek bölge yaklaşımıdır. Bu tip sıfır-boyutlu modellerde yanma olayı Wiebe fonksiyonu ile modellenmektedir. Bu makalede, HCCI prensibine göre çalışan tek silindirli bir Ricardo Hydra motoru tek bölge yaklaşımı kullanılarak modellenmiştir. Analiz çalışmalarında SPICE (Simulated Petrol Internal Combustion Engine) yazılımının modifiye edilmiş bir versiyonu olan TRICE yazılımı kullanılmıştır. Yanma analizlerinde, HCCI yanma modellerinde standart Wiebe fonksiyonu kullanımının maksimum silindir basıncının yüksek olarak tahmin edilmesi sonucunu doğurması nedeniyle, standart Wiebe fonksiyonunun modifiye edilmiş bir şekli olan Double-Wiebe fonksiyonu kullanılmıştır. Analizler, n-Heptan-Toluen karışımı için üç hava fazlalık katsayısı değerinde gerçekleştirilmiş ve elde edilen sonuçlar bir Avrupa Komisyonu Marie Curie destek programı (FP-6) projesi kapsamında Shell Araştırma Merkezine ait motor test laboratuvarında ölçülen deneysel verilerle karşılaştırılmıştır.Anahtar Kelimeler: HCCI motor, tek-bölgeli modelleme, net ısı yayılımı, dilindir basıncı Analysis of a Homogeneous Charge Compression Ignition (HCCI) engineby using a single-zone modelling method ABSTRACT Zero-dimensional models are commonly used to model HCCI engines. These models may contain single or multi zones. However, the simplest approach is the single-zone containing burned and unburned gases. In these type models, combustion progress is modelled by Wiebe function. In this article, a single-cylinder Ricardo Hydra engine, which is running in HCCI mode, was modelled by using single-zone method. In the analysis, a modified Shell SI engine code called TRICE was used. This code is a modified version of SPICE (Simulated Petrol Internal Combustion Engine) and modified for HCCI engine. In the combustion analysis, a modified Wiebe function called double-Wiebe function was used since standard Wiebe-function tends to over-predict the peak cylinder pressure in HCCI combustion models. The analses were performed for n-Heptane-Toluene blend with three excess air ratios and the results were compared to the experimental data measured in the engine test laboratuary of Shell Research Centre within an European Commission Marie Curie Transfer of Knowledge Scheme (FP6) project.

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“…by wrinkling the flame fronts; however, the effect of turbulence on HCCI combustion can be rather problem dependent. It is generally accepted that temperature stratification plays an important role in HCCI combustion [14][15][16]. With large temperature stratification the combustion duration can be longer and the pressure-rise-rate can be lower for a given combustion phasing.…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of Turbulent Combustion in a Spark-Assisted Homogenous Charge Compression Ignition Engine

Joelsson

Bai

2012

Combustion Science and Technology

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A large eddy simulation (LES) model was developed to simulate the combustion process in a spark-assisted homogeneous charge compression ignition (SACI) engine. First, an ignition and flame propagation model based on a reaction progress variable is presented. The reaction progress variable is defined based on the normalized cumulative heat release. Transport equation for the progress variable is derived where the source terms due to flame propagation and auto-ignition are modelled. The model is then applied to simulate the SACI combustion process with special focus on the interaction between the flame propagation introduced by the spark and the auto-ignition of the homogeneous charge. The engine simulated is a 0.5 litre experimental HCCI engine, with operation conditions ranging from spark-ignition controlled flame propagation to auto-ignition controlled HCCI combustion. In the first stage of SACI combustion, between the spark-ignition and the onset of HCCI auto-ignition, turbulence field governs the heat release rate and pressure-rise-rate in the cylinder. Increasing turbulence promotes the contribution of SI flame to the overall heat release. The second stage combustion, which is in the HCCI auto-ignition mode, is rather sensitive to the temperature field. The numerical results showed that with low initial temperature the SI flame mode prevails; with high initial temperature the HCCI mode prevails. With moderate initial temperature SI flame and HCCI ignition interact more closely, which results in higher sensitivity to the initial temperature and turbulence conditions. This may be the reason of having high cyclic variation found in the previous experiments. IntroductionIn light of today's public concern on green house gas (CO 2 ) emission and air pollution from combustion of fossil fuels, modern internal combustion engines are developed to have high efficient with low emissions. The benefits and shortfalls of the two major combustion concepts, spark ignition (SI) and compression ignition (CI), have over the past decades led to the development of homogenous charge compression ignition (HCCI) engines that can achieve high efficiency and low emissions of NOx and soot by using high compression ratio and excessive air or exhaust gas recirculation (EGR) in the fuel/air mixtures [1][2][3][4].In HCCI engines the combustion phasing is controlled by the auto-ignition of the lean charge. As the ignition delay time is sensitive to temperature of the charge the combustion phasing becomes rather sensitive to the initial flow and intake flow conditions. Furthermore, in HCCI engines the reaction fronts propagate at a velocity typically of an order of magnitude higher than the turbulent flame speed, the combustion duration in HCCI engine can be short if care is not taken to generate a suitable flow and temperature field in the cylinder. This is especially a serious problem when the engine runs at high load, where the pressure-rise-rate can be rather high, resulting in high noise level [5]. A recent review on HCCI combus...

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Potential of Thermal Stratification and Combustion Retard for Reducing Pressure-Rise Rates in HCCI Engines, Based on Multi-Zone Modeling and Experiments

Cited by 207 publications

References 32 publications

Study on Combustion Chamber Geometry Effects in an HCCI Engine Using High-Speed Cycle-Resolved Chemiluminescence Imaging

Study on Combustion Chamber Geometry Effects in an HCCI Engine Using High-Speed Cycle-Resolved Chemiluminescence Imaging

Homojen Karışımlı Sıkıştırma Ateşlemeli (HCCI) Bir Motorun Tek Bölgeli Modelleme Yöntemi Kullanılarak Analizi

Large Eddy Simulation of Turbulent Combustion in a Spark-Assisted Homogenous Charge Compression Ignition Engine

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