Knocking Behavior of Renewable Fuels in a Miller Cycle Gasoline Engine

n this study, relevant fuels with different biogenic and renewable compositions were
investigated in their knocking behavior and compared with an established, mainly fossil
based gasoline. Additionally, the impact on thermal efficiency and the particulate raw
exhaust gas emissions were considered. The selection of fuels was led by a methodological
approach in order to include a wide range of drop-in compatible compositions. The
reference fuel with a research octane number (RON) of 98 and an ethanol share of 10 %
(E10) was compared to fuel blends from a Methanol-to-Gasoline (MtG) and an Ethanol-to-
... mehr
Gasoline (EtG) production process and alternative fuels with 50% renewable share from
biogenic sources as cycloalkanes and ethanol. The variation of the RON lies between 95
and 100.
The measurements were performed on a DISI light duty single cylinder engine running in
Miller cycle and under stochiometric conditions. The design of experiments enabled the
demonstration of sensitivities of different engine operation parameters, such as intake air
temperature, exhaust gas pressure, engine speed and intake cam phasing.
In order to achieve comparable data for the evaluation of the fuels in their knocking
behavior, a reliable online knock detection based on the in-cylinder pressure was
introduced. For a deeper analysis of the knocking cycles, a statistic evaluation of the single
cycle characteristics was performed. With this, differences for the combustion cycles in
which knocking occurs, can be displayed.
The experiments show that differences in knock behavior cannot be described only by the
RON. Depending on the operation mode, knock occurrence is deviant to the expected
behavior. Furthermore, the occurrence of single cycles with a strongly accelerated burn
rate and high knock tendency for the use of particular fuels was displayed. As an origin, a
fuel-specific reactivity of the residual gas fraction is possible

In this study, relevant fuels with different biogenic and renewable compositions were investigated in their knocking behavior and compared with an established, mainly fossil based gasoline. Additionally, the impact on thermal efficiency and the particulate raw exhaust gas emissions were considered. The selection of fuels was led by a methodological approach in order to include a wide range of drop-in compatible compositions. The reference fuel with a research octane number (RON) of 98 and an ethanol share of 10 % (E10) was compared to fuel blends from a Methanol-to-Gasoline (MtG) and an Ethanol-to-Gasoline (EtG) production process and alternative fuels with 50% renewable share from biogenic sources as cycloalkanes and ethanol. ... mehrThe variation of the RON lies between 95 and 100.
The measurements were performed on a DISI light duty single cylinder engine running in Miller cycle and under stochiometric conditions. The design of experiments enabled the demonstration of sensitivities of different engine operation parameters, such as intake air temperature, exhaust gas pressure, engine speed and intake cam phasing.
In order to achieve comparable data for the evaluation of the fuels in their knocking behavior, a reliable online knock detection based on the in-cylinder pressure was introduced. For a deeper analysis of the knocking cycles, a statistic evaluation of the single cycle characteristics was performed. With this, differences for the combustion cycles in which knocking occurs, can be displayed.
The experiments show that differences in knock behavior cannot be described only by the RON. Depending on the operation mode, knock occurrence is deviant to the expected behavior. Furthermore, the occurrence of single cycles with a strongly accelerated burn rate and high knock tendency for the use of particular fuels was displayed. As an origin, a fuel-specific reactivity of the residual gas fraction is possible.