Combustion Geometry Optimization to Increase Alcohol-Fueled MCCI Efficiency

Diesel engines are critical to modern economies—moving 70% of the nation’s goods—but they remain coupled to the need for petroleum-based diesel fuel, which presents challenges. Diesel fuel prices are volatile (creating uncertainty about the fuel’s long-term economics), while the need for oil drives demand for imports. Emissions are challenging as well, as heavy-duty diesel engines generate 5 Gt of CO2 globally, while also contributing 30% of the smog emissions in polluted regions like California’s South Coast Air Basin. Many of the alternatives to diesel engines—such as spark ignited natural gas engines, or electric vehicles—lack the performance, range, or liquid-fueled simplicity that is required in many diesel applications. To solve this problem, this project will “take the diesel fuel out of the diesel engine”, by modifying engines to use low-carbon liquid alternative fuels (like ethanol and methanol, which are not soot-producing) in a high-efficiency, diesel-style combustion mode (but without the need for any diesel fuel). This technology elevates combustion temperatures in order to enable use of these non-traditional fuels without sacrificing performance (in fact increasing power by 25%). It harnesses the economic and environmental benefits of the fuels—reducing fuel costs by 10%, CO2 emissions by 40%, and smog emissions by 90%—without requiring a significant change in user behavior. The Phase I effort used both computational modeling and single-cylinder engine experiments to optimize combustion chamber geometry to leverage the advantages of these clean-burning fuels, allowing this concept to achieve efficiencies that are comparable to the baseline diesel engine but with much lower emissions. The proposed Phase II effort will continue development by translating the Phase I results and methodology to a commercial engine platform—a heavy-duty production engine provided by Cummins. A successful Phase II project will allow ClearFlame’s concept to reach state-of-the-art diesel engine efficiencies in a commercial platform, and will enable ClearFlame to prepare for pilot testing in generator sets and heavy-duty transportation engines in a Phase III project. This technology can be deployed in any sector that utilizes heavy-duty diesel engines. Initial expansion of this technology will target power generation, before translating to freight transportation, and finally to the remaining diesel-dominated sectors (like construction, marine, and agriculture). Once deployed throughout these heavy-duty diesel engine sectors, this technology would reduce global anthropogenic CO2 emissions by 2 Gt/year. At the same time, savings from lower fuel costs will be passed on to consumers in the form of lower cost of goods.