A System to Enable Mixing ControlledCombustion With High Octane FuelsUsing a Prechamber andHigh-Pressure Direct Injector

摘要

The demand for transportation energy is growing and thus improving the efficiency andreducing the pollutant emissions from this energy sector is critical. Transportation hashistorically been powered by the internal combustion engine (ICE). Many alternativetechnologies are being evaluated to replace the ICE, such as hydrogen fuel cells andbattery electrics. These technologies appear attractive at the vehicle-level but have manychallenges regarding life cycle emissions and lack of infrastructure. A more pragmaticapproach would be to use the current liquid fuels infrastructure with cleaner burning,renewable fuels that have the potential to be carbon neutral, such as low carbon alcohols(e.g., methanol, ethanol, propanol, and butanol). These alternative fuels tend to have ahigh-octane number, making them great candidates for conventional spark ignition (SI)engines. However, SI engines are plagued by several challenges when it comes to highload operation, such as pre-ignition, knock-limited peak torque, poor snap torqueresponse, high levels of cyclic variability, and sensitivity to varying fuel properties. Theobjective of this research is to develop a technology that will allow high octane fuels to beutilized in engines and utilize robust mixing controlled combustion. The proposedtechnology is a system which utilizes an active prechamber in the shape of an annulusand a high-pressure direct fuel injector. The active prechamber and the high-pressuredirect injector use the same liquid fuel, which could be any fuel that has relatively highvolatility and high resistance to autoignition (i.e., high-octane number). The activeprechamber is fired late in the compression stroke and hot jet flames are ejected fromthe prechamber. These jets ignite the direct injected fuel sprays near top dead center,establishing a mixing controlled combustion event. This will allow for robust operationacross the full engine operating space with clean burning renewable fuels, without theshortcomings of SI engines regarding knock-limited operation and part load efficiency.