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As environmental regulations become stricter and the demands for greater engine power and fuel economy increase, the need for better fuels for future engines is evident. NREL is working with industrial partners and using in-house laboratory capabilities to better understand fuel ignition and how it will apply to advanced combustion engines. The following list provides a brief overview of NREL projects in this research area:
Advanced Fuels R&D
IQT Studies of Pure Components
 In this project, NREL researchers are investigating how the molecular structure of pure components affects the ignition properties of fuels. Ignition delays of pure components are measured in the Fuels Chemistry Laboratory with the Ignition Quality Tester (IQT™). The dependence of ignition delay on temperature has been measured for many pure components and real fuels, and is related to molecular structure with understanding from kinetic reaction mechanisms coupled with computational chemistry tools. This type of understanding may allow us to develop fuel blending components that improve cold-start performance and optimize fuels for advanced combustion applications.
QSAR of Pure Components
 A quantitative structure activity relationship (QSAR) was recently developed that can be used to predict the cetane number of pure components. The model was developed from cetane number data available in the literature for approximately 250 compounds. The QSAR software calculates descriptors from the molecular structure based on geometry, electronic properties, connectivity, and group contributions. The values of these descriptors are then plugged into the model that predicts cetane number. In addition to the overall model, several submodels have been developed to more accurately predict the cetane number of compounds in particular classes (oxygenates, hydrocarbons, alkanes, olefins, etc.).
Fuels for Advanced Combustion Engines
 NREL is leading two projects aimed at identifying favorable fuel properties for advanced combustion engines. A light-duty project is taking place at Southwest Research Institute and a heavy-duty project at Mack Trucks, Inc. Both projects use engines equipped with Sturman Industries camless hydraulic valve actuation technology. These fully flexible engines allow for control of HCCI combustion via variable compression ratios, and a combination of internal and external exhaust gas recirculating (EGR) systems. The goal is to study renewable fuels that can be synthesized via the Fischer-Tropsch (F-T) process. Since the properties of F-T fuels can be customized to suit the particular application, we are working with synthetic fuel suppliers to determine an appropriate matrix of fuels to investigate boiling range and ignition quality.
More Information
See our other advanced diesel fuels publications for more information.
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