A Study on Cetane on Demand Technology Part 2: Gasoline Reforming and Ignitability Evaluation

In petroleum-based fuels, the combination of low-octane gasoline and a compression ignition combustion system has been proposed to reduce Well-to-Wheel CO2 emissions of automobiles. The gasoline components produced by FT synthesis have a low octane number, making them suitable for this combustion concept. In the current situation where low-octane gasoline is not widely available in the market, onboard reforming of commercial gasoline to increase the cetane number (lower the octane number) allows for compression ignition combustion even with commercial gasoline. This requires Cetane on Demand Technology, which enables compression ignition combustion with both commercial gasoline and low-octane gasoline. To reform commercial gasoline, a reformer with a spiral structure reactor and mechanical stirring air introduction was designed and prototyped based on the results of toluene reforming tests. Using N-hydroxyphthalimide (NHPI)-supported ZSM-5 as a catalyst, commercial gasoline was reformed. As a result, 25.5 liters of reformed gasoline was obtained. The ignitability of the reformed gasoline was evaluated using an internal combustion engine. Under premixed homogeneous conditions, no difference in ignitability was observed between the gasoline before reforming and the reformed gasoline. However, under non-uniform/diffusion combustion conditions, it was confirmed that the ignitability of the reformed gasoline improved compared to the gasoline before reforming. For the factor analysis, a chemical reaction calculations was conducted, and it was found to be due to the concentration of OH derived from the reformed gasoline. Under diffusion combustion conditions, the evaluation of engine combustion showed that reformed gasoline expands the lean limit and improves combustion stability in the low-load operating range.