Parametric optimization of direct injection CI engine to improve combustion characteristics

Abstract

To achieve emission standard norms and higher fuel efficiency conversion are the main concerns in diesel engines. The single parametric study approach might not attain the optimal combustion characteristics. In order to overcome this issue, multi objective study has been carried out to achieve the higher performance and simultaneously reduction of emissions. The main objective of present article is identifying the optimum set of the engine parameters for diesel fuel, which gives better performance and emissions. Numerical analysis was carried out by using CONVERGE CFD software. Numerical analysis were carried out by varying the Compression Ratio (CR) (12–16.5), Start of Injection (SOI) (0–25° bTDC), Fuel Injection Pressure (FIP) (500–1,400), and Exhaust Gas Recirculation (EGR) (0–40%). Response surface methodology was used for optimization. The parameters are optimized for minimizing the NOx, soot, and ISFC by using the Response Surface Methodology (RSM). Regression equations were developed for the responses such as ISFC, NOx, and soot. It was observed that the interaction effects also play a major role in determining the performance and emission characteristics of the engine. The optimum combination of operating parameters was found to be CR 14.55, SOI 16.29° bTDC, FIP 855 bar, and EGR 26.15% with a composite desirability of 0.94. The corresponding NOx and soot emissions are reduced by 40.3% and 52.38%, respectively, and a marginal reduction in the ISFC is accomplished. Mixture homogeneity (TFDI) was improved 27% for optimum case compared to baseline configuration.

Effect of injection system parameters on overall performance of a small diesel engine

“…Equation (1) shows the mathematical formula to calculate uncertainty based on the considered combustion characteristics:…”

“…The formation of NOx emission and dissociation of gases were mainly dependent on the mean gas temperature. 1,15 NOx formation was generally taking place at a higher temperature. Figure 9 shows the behavior of MGT with respect to CA for different IP and SOMI.…”

“…Such engines have advantages like high thermal efficiency, durability, compactness, robust, and less maintenance. 1 However, exhaust gases emitted from these engines polluted most of the cities in the country. 2,3 Uptil now, all the small diesel engines use conventional mechanical systems for supplying the appropriate fuel quantity at the end of the compression stroke.…”