Abstract
KEYWORDS Soot, Exhaust emission, Hiroyasu-NSC, Particulate Mimic model, Methods of moment
ABSTRACT
The undisputable advantages in terms of time and cost saving for soot emission study have made the computational analyses become more preferable. Current development of computer programs with higher precision of mathematical models brings simulation works closer to the real engine combustion environment. The objective of this study was to investigate the soot particles formation using different level of complexity of soot models available. This investigation of in-cylinder soot concentration has been carried out using relatively recent commercial Computational Fluid Dynamic (CFD) software, CONVERGE CFD. In conjunction with exploring its full capabilities, studies on in-cylinder soot formation has been performed using a detailed soot model of Methods of Moment and its results were compared with that of a simple two-step soot model of Hiroyasu-NSC model. The combustion process of a 493 cc, single-cylinder direct injection diesel engine was simulated for a close-cycle combustion environment which is from inlet valve closing (IVC) to exhaust valve opening (EVO). Results show that simpler soot model gives higher soot mass peak value while detailed soot model with lower soot mass value provides extra information of soot size, number density, volume fraction and soot mass for every related soot formation process. An important limitation of the current study is that it was all conducted only by simulation process without any validation by experimental work, and the maximum number of cells generated was set to 500,000 for the computational analyses purposes. The analysis and comparison of soot particles using different level of complexity of soot models in this paper specifically performed by this particular software is considered new and have not been reported before. Overall, CONVERGE-CFD software is an attractive computational tool to study various soot models as it has the ability to analyze soot formation process using detailed as well as simpler soot models.