Numerical analysis of the mixture stratification, combustion and heat losses in an engine with passive TJI pre-chamber operating with hydrated ethanol

The land transport sector currently faces a scenario of increasing participation of electrified vehicles in the global fleet composition, with prospects for evolution in the coming years. This fact has been stimulating a rapid shift in the automotive industry towards research and development initiatives focused on electrification. Foreseeing a period of revolution in vehicle propulsion systems, many automakers are redirecting from investing in new concepts of internal combustion engines to other technologies, such as hybrid and electric vehicles, batteries, and fuel cells. Technologies that take advantage of the potential of the local energy matrix, considering the geographic, demographic and social characteristics of each country and the increase of solutions diversity for the sustainable future of the transport sector are indispensable. Advanced ignition systems, such as pre-chamber ignition, can improve the combustion process of engines, increasing fuel conversion efficiency and reducing the emission of polluting gases. Therefore, the present work developed and optimized a pre-chamber ignition system applied in a single-cylinder research engine operating in stoichiometric condition and fueled with hydrated ethanol. The experiments were carried out on the AVL 5495 single-cylinder research engine, while numerical simulations were performed using the 3D software CONVERGE. The impact of the pre-chamber’s volume in the jet ejection delay, as well its influence on the convective heat transfer to the wall, were extensively discussed. The smaller pre-chamber volumes produced shorter ejection delay due to the larger flame area, producing higher flame burn rate. Reducing the pre-chamber volume ratio from 2.5% to 1% produced a reduction up to 59% in the flame ejection delay. In addition to that, decreasing internal area due to the volume reduction caused a reduction of about 53% in convective heat transfer, leading the engine towards higher thermal efficiency.