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Quantification of the Relationship between Surrogate Fuel Structure and Performance
Final rept. 21 Jul 2009-20 Jul 2012
IMPERIAL COLL OF SCIENCE TECHNOLOGY AND MEDICINE LONDON (UNITED KINGDOM) DEPT OF MECHANICAL ENGINEERING
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The project commenced in August 2009 and the current final report outlines some of the progress made during the grant period. The overall objective of the research has been to contribute to a quantitative understanding of combustion processes to a degree that permits a rational link between the structure of the fuel and observed performance. This effort explored the geometries and energetics of a group of bimolecular hydrogen exchange reactions involved in the combustion of nPB. Energies from a wide selection of methods were compared with the CCSDTaug-cc-pVDZM06-2X6-311G3df,3pd level of theory, the most accurate achievable for molecules the size of nPB. It was established that the energies produced at M06-2X6-31G2df,p level provide a comparatively good match. Thermodynamic data, based on the G4 calculations, was also produced in the form of JANAF polynomials for the compounds involved. Kinetic rate data was determined for a range of temperatures using TST and TSTSCT. For the current bimolecular reactions no variational character was found and we recommend the use of the TSTSCT determination obtained at the M06-2X6-31G2df,p level. However, for reaction 6, a disagreement of -6.9 kJ mol-1 in the barrier height, as compared to the CC calculation, has been highlighted and we therefore recommend the rate based on TST using CCSDTaug-cc-pVDZ energies. Some agreement was found between our calculations and older reaction class based determinations. However, for the CH3 based extractions significant deviations were noted. Finally, the current exercise has allowed the identification of candidate functionals and basis sets that describe the nPB system with sufficient accuracy.
APPROVED FOR PUBLIC RELEASE