Development of a Turbulent Jet-Controlled Compression Ignition Engine Concept Using Spray-Guided Stratification for Fueling a Passive Prechamber

Improving thermal efficiency of an internal combustion engine is one of the most cost-effective ways to reduce life cycle-based CO₂ emissions for transportation. Lean burn technology has the potential to reach high thermal efficiency if simultaneous low NOx, HC, and CO emissions can be achieved. Low NOx can be realized by ultra-lean (λ ≥ 2) spark-ignited combustion; however, the HC and CO emissions can increase due to slow flame propagation and high combustion variability. In this work, we introduce a new combustion concept called turbulent jet-controlled compression ignition, which utilizes multiple turbulent jets to ignite the mixture and subsequently triggers end gas autoignition. As a result, the ultra-lean combustion is further improved with reduced late-cycle combustion duration and enhanced HC and CO oxidation. A low-cost passive prechamber is innovatively fueled using a DI injector in the main combustion chamber through spray-guided stratification. This concept has been experimentally demonstrated as detailed in this article to achieve 47.7% peak indicated efficiency and below 1 g/kWh engine-out NOx emission with initial single-cylinder engine hardware. Further systematic combustion system optimization is underway to demonstrate state-of-the-art efficiency and emissions at a wider operating range.