Grant: Discovery Grants Program - Individual

To make mobile propulsion systems more efficient and cleaner to pave the way towards a carbon neutral transition, the proposed research focuses on clean and efficient combustion of low- and zero-carbon fuels in optically accessible combustion chambers, rapid compression machine systems, and engine prototyping platforms. An emphasis is made to identify the leading challenges of ignition and burn-out control of the low-carbon fuels and thus to improve the energy efficiency and exhaust emissions. In line with worldwide efforts to tackle the combustion pollutants, CO2 production, and energy sustainability in mobile propulsion, the applicant has realized reactivity-modulated combustion using fuels of renewable sources with lower-carbon footprints. The energy sustainability by adapting the fuel suitability effectively in combustion control is thus expanded, and by lowering the flame temperature with mixture dilution, the ultra clean combustion that is applicable to plug-in hybrid electric vehicles is achieved. The applicant's research achievements benefited the industry by adapting low- and zero-carbon fuels, which are invaluable for transportation scenarios that are difficult to electrify completely, such as large commercial trucks, ocean marine vessels, and long-haul aircraft. To understand the fundamental differences of zero carbon fuels, i.e., neat ammonia and hydrogen, between the high and low temperature combustion systems, the proposed research also focuses on exploring the ignition and flame propagation criteria, including ammonia and hydrogen blends; and to study the effectiveness of low temperature combustion on ultra low NOx emissions across wide air-fuel ratio and inert gas dilution. An emphasis is given to the leading challenge, i.e., the trade-off between the NOx reduction and NH3 slip; an approach of high volumetric-power intensity is to be devised to affect ammonia combustion, through the assistance of power modulated ignition and early flame promotion techniques. To target broad mobile propulsion applications, the proposed research will correlate the ignition and combustion processes with transient electric signals, e.g., as provided by the ion current detection or active plasma probing for on-the-fly diagnostics to enable flex-mode combustion control dynamically with low- and zero-carbon fuels. The overall research is to be implemented under independently controlled fuel-air mixture temperature, pressure, strength, and homogeneity, in addition to precisely modulated oxygen concentration and turbulence intensity prior to ignition. Cutting-edge ignition strategies are to be devised to suit the specific empirical conditions. Owing to the tireless efforts made by the applicant's team, the required experimental apparatus and expertise have already been well established and will be further enhanced to excel in the proposed research. The HQPs will gain the relevant technical skills for future workforce in industry and academia.