In-Cylinder Soot Particle Distribution in Squish Region of a Direct Injection Diesel Engine

International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:14 No:05 51 In-Cylinder Soot Particle Distribution in Squish Region of a Direct Injection Diesel Engine Muhammad A. Zuber, Wan Mohd F. Wan Mahmood, Zulkhairi Zainol Abidin. and Zambri Harun., Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, Bangi, Malaysia Abstract— The size and distribution of in-cylinder soot [9], sulfation of building stones [10] and damage the engine. particles affect the sizes of soot particles emitted from exhaust Soot damage the engine by increase the engine wear by tailpipes as well as the soot in oil. The simulation work reported degrading the oil that reduces the flow ability of the oil and in this paper focuses on the study of soot formation and cause the need to change the oil frequently [11]-[14]. Thus it movement inside a diesel engine with in-depth analysis of soot particles in the squish region. Soot particles in the squish region is important to understand soot formation, behavior and have high potential to be deposited onto the cylinder wall, and movement inside the engine cylinder until emission so counter subsequently penetrate into engine lubrication system and measure action can be taken to reduce the soot and exhaust contaminate the oil. The prediction of a soot particle pathline and gases emission. size distribution was performed using post-processed in-cylinder Exhaust gas emission from a direct injection diesel engines combustion data from Kiva-3v computational fluid dynamics consist of carbon monoxide (CO), nitrogen oxide (NOx), (CFD) simulations with a series of Matlab routines. Only soot oxidation and soot surface growth process were considered in this sulfur dioxide (SO2), unburned hydrocarbons (UHC) [15] and study. Coagulation and agglomeration of soot particles were not particulate matter (PM) [16], [17]. Particulate matter taken into account. Soot particles were tracked from 8 crank composed of 10 % of fuel, 16 % of oil, 10 % of combination angle (CA) degree after top dead center (ATDC) as soot starts to sulfuric acid and water and, 64 % of soot [18]. form in high concentration until 120 CA degree ATDC at exhaust A modelling of soot formation with detailed chemistry and valve opening (EVO). The soot particle size and its distribution physics had been conducted by [1] and a series of model were analyzed at different crank angles. In the squish region, the most dominant soot particle size was 20-50 nm at earlier crank containing the gas-phase reaction, aromatic chemistry, soot angle and in 10-20 nm range at 120 CA ATDC. The percentage of particle coagulation, soot particle aggregation and surface soot loss in the squish region was analyzed to be 23.2 % and the growth were produce. According to [19] the soot formation soot loss was higher at earlier crank angle until 10 CA degree can divided to four major processes: homogeneous nucleation ATDC due to high rate of oxidation. of soot particles, particle coagulation, particle surface reactions and particle agglomeration. On the other hand, some Index Term— soot, particle tracking, squish region, in- cylinder soot size researcher focus on the soot properties [20], soot mechanism [2], [4], in-cylinder soot particle movement [3] and soot size I. INTRODUCTION [21]. While [22] characterize the soot formation reaction by The study and investigation of combustion and soot inside a four steps: 1.Particle nucleation, 2.Particle surface growth, diesel engine cylinder had been conducted by researcher via 3.Particle surface oxidation, 4.Particle coagulation 5.PAH experiment [1], [2] and simulation [3], [4]. This research deposition on the particle surface. gains the attention of the researcher due to the rule, restriction Various experimental studies had been conducted by [1], and regulation enforcement to reduce the exhaust gas emission [2], [20], [21], [23]-[25] to understand the formation and produce by diesel engine [5]. The exhaust gases produced can behavior of soot inside engine cylinder. An in-cylinder soot lead the severe health complication to human [6]-[8] and plant formation and oxidation had been carried out by [23] using the two-dimensional Laser-Induced Incandescence (LII) and the result showed that at 2° CA ATDC the soot start to form and This work was supported in part by the the Ministry of Higher Education soot concentration start to increase at 6° to 12° CA ATDC. of Malaysia and Universiti Kebangsaan Malaysia under FRGS/1/2013/TK01/UKM/02/2 and GGPM-2011-055 research grants. But after 12° CA ATDC soot concentration intensity start to Muhammad Ahmar Zuber. is with Department of Mechanical and decrease. An experiment was conducted to study the Materials Engineering, National University of Malaysia 43600 Bangi, hygroscopic properties of carbon and diesel soot particles by Malaysia (e-mail: [email protected]). Wan Mohd Faizal Wan Mahmood is with Department of Mechanical and [20]. They use diesel engine to produce soot particle and spark Materials Engineering, National University of Malaysia 43600 Bangi, discharge between two graphite electrodes to produce carbon Malaysia (e-mail: [email protected]). particle. The particle size found to be at 20-500 nm and the Zulkhairi Zainol Abidin is with Department of Mechanical and Materials Engineering, National University of Malaysia 43600 Bangi, Malaysia (e-mail: primary carbon particle at 10 nm and primary soot particle at [email protected]). 25 nm. Zambri Harun is with Department of Mechanical and Materials Soot particle mass, size and distribution were effected by Engineering, National University of Malaysia 43600 Bangi, Malaysia (e-mail: [email protected]). engine load, operation mode and type of fuel. A study by [21] 144105-2929-IJMME-IJENS © October 2014 IJENS I J E N S International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:14 No:05 52 on the particle size distribution during emission concluded that particle diameter found in the literature and typical diesel the engine that operate at higher load produce larger soot engine. At earlier combustion in engine, soot formation in the particle size with wider size distribution. This happened due to head of spray can be neglected due to high temperature and the nucleation process, condensation in exhaust emission, soot formation is limited to the beginning of diffusion burn coagulation and agglomeration of soot particle with water phase but after that oxidation will take place. content in exhaust gases. At higher engine load, more soot Work on the soot formation in the diesel engine and their were produce because of the increase of sulfur, ash, heavy interest is in the crevice near the cylinder wall were studied by hydrocarbon and aromatic content. While [24] recorded that [31], [33], [34]. At start of the ignition the soot and at the end soot embedding with hydrocarbon (e.g., Polycyclic Aromatic of expansion stroke the soot more likely to be transported to Hydrocarbon, PAH) can produce soot particle with smaller the wall liner and crevice region by the squish motion. The size. The different in-size of soot particle by different soot transport to the wall liner is depended on the soot density researcher is due to the different type of measurement and recirculation of charge this can be reduced by early techniques or machines use. Each measurement technique or injection of fuel [34]. machines has its own merit. The prediction the soot particle size and distribution in this As oppose to the experimental method, some of the paper was achieved by post processing the result obtained researcher [1], [3], [4], [22], [25]-[34] study the soot formation from simulation using CFD software, Kiva-3v. Kiva-3v and behavior by conducting a simulation with mathematical software was chosen due to its flexibility to be adapted and modeling. Pang et al. [30] conducted a simulation on the soot modified according to the user preference model. The Kiva-3v precursor formation mechanism using CFD software Ansys- CFD code has open architecture that allows researchers to Fluent with chemistry solver, Chemkin-CFD. A detailed understand, investigate and amend the codes [29]. Kiva-3v can chemistry soot models for internal combustion engine were be used to simulate air flow, fuel sprays, and combustion in used in a CFD simulation using Kiva reported by [1]. As PAH practical combustion devices. Originally, Kiva was intended was treated as a soot precursor in the simulation and the soot for three dimensions simulation for modelling flows in particle size was 2 nm with 667200 numbers of soot particle gasoline and diesel engine. It was then expanded on other were recorded at 60° CA ATDC. Another research by [4] was combustion devices such as turbines and furnaces. Kiva performed with various injections timing model result shown features the ability to calculate air flows in complex that the soot concentration is high at 0-30° CA ATDC for all geometries with fuel spray dynamics and evaporation, mixing cases and the multidimensional model they used was very of fuel and air, and combustion with resultant heat release and helpful. Puduppakkam et al. [28] use moment method with exhaust-product formation [35]. Hong et al. [36] used Kiva-3v FORTE CFD software to track soot formation and evolution to develop soot model using realistic physical and chemical inside a direct injection diesel engine. The findings showed equations as bases with reasonable cost and produced that the density of soot particle was peak at 10° CA ATDC excellent agreement with experiment. and decrease afterward. While at 30-40° CA ATDC soot with This simulation is in the limit of expansion stroke using a larger size were found and the size decrease afterward. The series of algorithm to predict it size and pathline.

Load more