High-performance bio-derived fuels (HPFs) are an alternative to conventional petroleum fuels that could reduce the carbon footprint of internal combustion engines. The combination of high-HPF-content fuels with advanced engine technologies (such as advanced compression ignition [ACI] engines) is a promising pathway to more efficient engines with lower harmful emissions. One of the key fuel properties for the operation and control of ACI engines is φ-sensitivity. However, regular gasoline is not very φ–sensitive at naturally aspirated conditions, meaning that intake boosting is required to take advantage of this property. Thus, there is strong motivation to design an HPF fuel blend that increases φ–sensitivity for ACI engines, while simultaneously increasing RON and octane sensitivity (S) to also make the fuel blend better for modern spark-ignition engines.<br/>In this study, the authors used a holistic approach to design high-HPF-content fuel blends by mixing high-reactivity, high- φ-sensitivity species with low-reactivity, high-RON and high-S species. Two different approaches were tried: 1) using high-reactivity HPF species to provide φ-sensitivity combined with low-reactivity non-HPF species for high RON and S, and 2) using low-reactivity HPF species to provide high RON and S combined with high-reactivity non-HPF species for high φ-sensitivity. Simulations show that it is more effective to obtain φ-sensitivity from high-reactivity non-HPF hydrocarbons (such as n-alkanes or n-olefins) and use HPFs to increase RON and S. This approach was then used to computationally design a 5-component fuel blend (termed CB#2) that contains 40%vol HPFs, as a mixture of 2-methyl furan and 2, 5 dimethyl furan (which is representative of the products of a viable pathway to make HPF furans from bio-feedstock). Simulations show promising results when CB#2 is compared to a regular E10 gasoline (RD5-87). CB#2 was also experimentally evaluated in the Sandia low-temperature gasoline combustion (a form of ACI) engine. These tests included an evaluation of the autoignition reactivity of CB#2 compared to RD5-87 at naturally aspirated conditions, and a comparison of the maximum load attainable with CB#2 and RD5-87 at a high-boost condition. Then, the φ–sensitivity of CB#2 was evaluated and results are compared to those of RD5-87. Finally, the effectiveness of ignition enhancers, such as 2-ethylhexyl nitrate, to work with CB#2 and RD5-87 was studied.

Can φ–sensitivity, RON and S of a fuel be increased simultaneously? A combined computational and experimental approach to a high-HPF-content fuel blend for ACI engines

ACS Spring Meeting 2021

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