EAGER: Biodiesel / Ethanol RCCI Combustion Exploration at Multiple Engine Loads and Speeds

Texas A&M Engineering Experiment Station, College Station TX

Investigators

Abstract

Current combustion systems predominantly are ?single-fuel? devices. For example, the ubiquitous spark ignition engine routinely uses gasoline as a fuel, while the typical compression ignition engine uses diesel as a fuel. There are well-founded reasons for this existing paradigm. In simple terms, the high volatility of gasoline makes it amendable for pre-cylinder (or early direct-cylinder injection) vaporization and subsequent premixing. Likewise, the high ignitability of diesel fuel makes it appropriate for compression ignition. The past century of engine development, however, has witnessed tremendous growth and advancement of both spark- and compression-ignition engines. A reasonable question becomes, what?s the best fuel for the advanced combustion engine? Some preliminary efforts have suggested that the best fuel may in fact be a combination of two fuels. Specifically, the Reactivity Controlled Compression Ignition mode of combustion ? which is a type of low temperature combustion ? uses both a highly volatile fuel (such as gasoline) along with a highly ignitable fuel (such as diesel) in the same apparatus. This shift in the paradigm requires exploration of other qualifying fuels, particularly alternative fuels, in an effort to discern if this radically different approach may yield the high payoff it potentially promises. Several research questions exist regarding such science, including how the fuels? interactions may affect chemistry of the reaction, how physical fluidic processes (such as penetration, breakup, atomization, and vaporization) are affected by the presence of a potentially reactive mixture, and how soot formation processes are affected by the interaction with a reactive mixture. This research aims to explore the viability of hydrous ethanol and biodiesel as fuels in dual-fuel reactivity controlled compression ignition (RCCI) low temperature combustion mode in a medium-duty diesel engine and to compare their response ? in terms of engine power, efficiency, and in-cylinder processes (such as fluid processes, chemistry, and emissions formation) ? with RCCI using conventional gasoline and diesel fuels. The overarching benefit of RCCI seems to be that it can simultaneously reduce NOx and soot from diesel engines while also maintaining high efficiency and specific power. The research makes use of experimental engine research facilities with controlled studies of the fuel and air mass and rate of reaction. This research intends to improve the end use efficiency of work conversion devices (such as combustion engines) while maintaining environment quality (i.e., low emissions) and assessing the viability of alternative fuels in combustion systems. Implementation of RCCI results in high chemical-to-work conversion efficiencies while maintaining low formation rates of nitrogen oxides and soot, both which contribute to poor atmospheric quality and local SMOG. The attainment of high efficiency combustion systems, particularly with the use of bio-based alternative fuels, allows society to move toward carbon-neutrality. Additionally, the research will further efforts to recruit and educate underrepresented students through hands-on experimental research. Funds will be leveraged to support graduate and undergraduate research to improve the number of students formally educated in STEM disciplines.