Untersuchung abnormaler Verbrennung in Kombination mit zukünftigen erneuerbaren Kraftstoffen (E-Kraftstoffen)
As presented in multiple forecasts [1, 2], internal combustion engines (ICE) will remain a relevant technology for passenger and heavy-duty transport sector for the next decades. For this reason, the improvement of engine efficiency and the de-carbonization of the fuels for engine operation is of greatest importance to fulfill the international targets on CO2 emissions to slow down the global warming. Regarding efficiency improvements, one the aspects that limits the efficiency of spark-ignition (SI) combustion engine is an abnormal combustion process. Among the SI combustion anomalies, engine knock and pre-ignition are the most limiting in terms of efficiency [3] and adoption of new technologies. Regarding de-carbonization of the fuels for ICEs, an important role is played by the hydrogen produced from renewable energy sources, which can be directly used in the engines or combined with CO2 captured from the atmosphere to generate the so-called “e-fuels” (e.g., e-methanol) Among the synthetic liquid fuels, methanol shows great potential for increasing efficiency while reducing pollutant emissions [4].
The focus of this research is the investigation of abnormal combustion events (knock and pre-ignition), also in combination with renewable fuels like methanol and hydrogen. Both fuels are known to be more knock-resistant than conventional gasoline fuels, but more prone to surface pre-ignition due to their lower ignition temperature [5, 6]. The knocking and pre-ignition behavior of methanol and hydrogen are experimentally investigated at a single-cylinder SI engine. The scope is, from one side, to characterize the behavior of these fuels, to compare it with the better-known behavior of gasoline, and to understand the potential benefits and operating strategies for future application. From the other side, the fundamental mechanisms that bring to end-gas auto-ignition and to pre-ignition are investigated. The data is then used to provide input and validation basis for the development of simulation models.
Example of abnormal "Mega-knock" cycle in comparison to standard engine cycles measured at the ITV SI-SCE. The Megaknock cycle results from a pre-ignition that causes a strong auto-ignition of the end-gas (knock).
Referenzen
[1] F. Leach, G. Kalghatgi, R. Stone, P. Miles, The scope for improving the efficiency and environmental impact of internal combustion engines,Transportation Engineering, Volume 1, 2020.
[2] R. D. Reitz, H. Ogawa, R. Payri, et al. IJER editorial: The future of the internal combustion engine. International Journal of Engine Research. 2020;21(1):3-10.
[3] G. Kalghatgi, Knock onset, knock intensity, superknock and preignition in spark ignition engines. International Journal of Engine Research. 2018;19(1):7-20.
[4] C. Wouters, B. Lehrheuer, B. Heuser, S. Pischinger (2020). Gasoline Blends with Methanol, Ethanol and Butanol. MTZ Worldwide, 81(3), 16–21.
[5] S. Verhelst, J. W.G. Turner, L. Sileghem, J. Vancoillie, Methanol as a fuel for internal combustion engines, Progress in Energy and Combustion Science, Volume 70, 2019.
[6] S. Verhelst, T. Wallner, Hydrogen-fueled internal combustion engines, Progress in Energy and Combustion Science, Volume 35, Issue 6, 2009.