Experimental Evaluation of a Gasoline-like Fuel Blend with High Renewable Content to Simultaneously Increase φ-Sensitivity, RON, and Octane Sensitivity

High-performance renewable fuels (HPFs) are an alternative to conventional petroleum fuels that could greatly 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)] that have been demonstrated to provide efficiencies well above those of diesel engines is a promising pathway for substantial reductions in CO2 with low criteria emissions. One of the key fuel properties for the operation of ACI engines is phi-sensitivity. However, regular gasoline is not very phi-sensitive under naturally aspirated conditions, meaning that intake boosting is required to take advantage of this property. Thus, there is strong motivation to design HPF fuel blends that improve phi-sensitivity at lower pressures and simultaneously increase the research octane number (RON) and octane sensitivity (S) to make them improved fuels suitable for both ACI and spark-ignition engines. In this study, a holistic methodology was used to design a five-component gasoline-like blend (termed CB#2) that contains 40% vol of a mixture of 2-methyl furan and 2,5-dimethyl furan (which is representative of products of a viable pathway to make furans from bio-feedstock). Simulations show promising results when CB#2 is compared to regular E10 gasoline (RD5-87). Measurements show that CB#2 has RON = 97.4 and S = 13.6, improving the RON and S of RD5-87 by 5.4 and 6.3 units, respectively, and suggesting that CB#2 is suitable for spark-ignition engines. Fuel blend CB#2 has been experimentally evaluated in the low-temperature gasoline combustion engine at Sandia National Laboratories, and the results are compared with those of RD5-87. Fuel blend CB#2 requires less intake heat than RD5-87 to autoignite under premixed, naturally aspirated conditions, indicating that CB#2 operates under the ACI mode easier than regular gasoline. Both CB#2 and RD5-87 allow virtually the same maximum engine load under premixed, high-boost conditions. Finally, CB#2 shows significantly higher phi-sensitivity than RD5-87.

Automated summary

High-performance renewable fuels are a promising alternative to reduce carbon emissions from internal combustion engines when combined with advanced engine technologies. The key to achieving substantial reductions in CO2 emissions is designing fuel blends with phi-sensitivity, high research octane number, and octane sensitivity suitable for both ACI and spark-ignition engines.