A Novel Group Contribution Method for the Prediction of the Derived Cetane Number of Oxygenated Hydrocarbons
2015
Dahmen, Manuel | Marquardt, W.
The assessment of the ignition quality of a wide range of oxygenated hydrocarbons is one key challenge in the identification of novel molecular entities qualifying as biofuels or biofuel blend components derived from oxygen-rich lignocellulosic feedstocks. The present contribution summarizes the results from a comprehensive experimental screening campaign targeting a diverse set of pure-component oxygenated hydrocarbon fuels and their ignition characteristics in an ASTM D6890 Ignition Quality Tester (IQT). This constant-volume combustion chamber experiment has been chosen because of its rapid screening potential. The unique collection of data is utilized for group contribution modeling with the aim of unraveling relationships between the ignition delay observed in IQT experiments and the fuel’s molecular structure. We propose a simple, yet predictive, estimator for the derived cetane number of pure oxygenated hydrocarbons covering acyclic and cyclic, branched and straight, saturated and unsaturated hydrocarbons as well as alcohols, ethers, esters, ketones, aldehydes, and aromatic and polyfunctional compounds. The calculation procedure does not require involved computational tools nor any information that could not be derived from the two-dimensional molecular graph. The model prediction yields a first estimate of the autoignition capability of a fuel candidate, if a sufficiently large and pure sample is not available.
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