Application of micro-genetic algorithms to optimize piston bowl geometries for heavy-duty engines running on diesel and 1-Octanol fuels

Abstract

This study presents the developments in piston bowl geometry and renewable fuels for a heavy-duty diesel engine to approach the CO2 emission targets set by the European Union. 3D computational fluid dynamics were performed within the framework of a micro-genetic algorithm which was used as a global optimization method to evolve piston bowl geometries. Furthermore, this paper discusses using 1-Octanol as a renewable substitute for fossil diesel fuel. 1-Octanol’s oxygenated nature and straight-chain structure demonstrate high potential in improving combustion and engine efficiency.The results of the numerical investigations show that the optimized piston bowl geometry from a micro-genetic algorithm for diesel fuel improved the indicated specific fuel consumption and reduced indicated specific CO2 emissions by up to ∼5% and ∼2% respectively. This is achieved due to improved air utilization with the optimized piston bowl geometry. The optimized piston bowl geometry results in increased air utilization in the squish region and reduced loss in spray movement due to bowl design. 1-Octanol as fuel demonstrates up to ∼1.8% increase in indicated thermal efficiency and ∼2% reduction in indicated specific CO2 emissions when compared to diesel fuel for base piston bowl shape. The oxygen content and lower C / H ratio in 1-Octanol fuel lead to faster and improved combustion, which helps increase indicated thermal efficiency compared to diesel fuel. The diesel-optimized piston bowls for 1-Octanol show minor improvement in fuel consumption, air utilization, and emissions.