Abstract
The use of methanol and ethanol in internal combustion engines forms an interesting approach to decarbonizing transport and securing domestic energy supply. The physico-chemical properties of these fuels enable engines with increased performance and efficiency compared to their fossil fuel counterparts. The development of alcohol-fuelled engines has been mainly experimental up till now. The application of an engine cycle code valid for these fuels could help to unlock their full potential. For this reason, our research group decided to extend its in-house engine code to alcohols. This paper discusses the requirements for the construction of a two-zone thermodynamic model that can predict the power cycle, pollutant emissions and knock onset in alcohol engines.
We reviewed the properties of alcohol fuels and their use in dedicated engine technology. From this information we identified the characteristics relevant to combustion engines and defined the areas the model should cover in terms of cylinder pressure, temperature, residual gas fraction, etc. Next, we investigated which building blocks of the current model will need adaptations. For the laminar burning velocity of alcohol-air mixtures, our literature review revealed a lack of data at engine-like conditions. Upon inspection of the pollutant formation models, we found that special attention should be paid to the formation of aldehydes and selected a suitable formation model. Finally we decided that a knock prediction model based on a one-step Arrhenius-type autoignition reaction is best suited for our purpose. Future work will further focus on each of these building blocks separately in order to come to a comprehensive model for the combustion of alcohols in spark-ignition engines.
Keywords: Alcohols, Spark Ignition Engine, Thermodynamic, Modeling