CO2 neutral heavy-duty engine concept with RCCI combustion using seaweed-based fuels 2020-01-0808
This paper focusses on the application of bioalcohols (ethanol, butanol) derived from seaweed in Heavy Duty (HD) Compression Ignition (CI) combustion engines. Seaweed based fuels don’t claim land and are not in competition with the food chain. Currently, the application of high octane bioalcohols is limited to SI engines. The Reactivity Controlled Compression Ignition (RCCI) combustion concept allows using these low carbon bioalcohol fuels in CI engines with associated higher than SI engine-like efficiencies. This contributes to reducing tailpipe CO2 emissions as is required by (future) legislation and reducing fuel consumption, i.e. Total-Cost-of-Ownership (TCO). Furthermore, it opens the HD transport market for these low carbon bioalcohol fuels from a novel sustainable biomass source .
This paper first discusses the complete CO2 life-cycle of the seaweed based bioalcohol fuels considering both well-to-tank and tank-to-wheel efficiencies and their potential as an energy source for HD transport. Ethanol (E85) and butanol are considered as the most viable fuels derived from seaweed. The potential of these fuels in RCCI mode regarding efficiency and operating range, is evaluated by changing blend-ratio (BR), timing and EGR on a multi-cylinder EURO VI engine.
Results for E85-RCCI demonstrate that CI engine like efficiencies are feasible. First results using biomass based butanol show greater difficulty in realizing targeted efficiencies. Here, the higher fuel reactivity and higher boiling temperature provide a greater challenge. In order to identify development directions for improved efficiency, measurements with butanol-RCCI are conducted on a single-cylinder engine setup. These show that CI engine like efficiencies are feasible with the use of seaweed based butanol.
The demonstrated potential of seaweed based fuels is an important driver for upscaling the production process of seaweed based fuels. Furthermore, future development activities will focus on improving the brake thermal efficiency of the RCCI engine running on seaweed based fuels.
Xander Seykens, Cemil Bekdemir, Jinlin Han, Robbert Willems, Jaap Van Hal
TNO Automotive, Eindhoven University of Technology, ECN Part of TNO