Chem. J. Chinese Universities ›› 2016, Vol. 37 ›› Issue (2): 328.doi: 10.7503/cjcu20150647

• Physical Chemistry • Previous Articles     Next Articles

Studies on the Calculation of Lennard-Jones Parameters for Intermediates in Hydrocarbon Combustion

SUN Yanjin1, YAO Qian2, LI Zerong2,*(), LI Juanqin3, LI Xiangyuan3   

  1. 1. School of Aeronautics&Astronautics, Sichuan University, Chengdu 610065, China
    2. College of Chemistry, Sichuan University, Chengdu 610064, China
    3. College of Chemical Engineering, Sichuan University, Chengdu 610065, China
  • Received:2015-08-14 Online:2016-02-10 Published:2016-01-04
  • Contact: LI Zerong E-mail:lizerong@scu.edu.cn
  • Supported by:
    † Supported by the National Natural Science Foundation of China(Nos.91441114, 91441132)

Abstract:

Lennard-Jones(L-J) parameters were used in combustion modeling as transport parameters and in pressure-dependent rate-coefficient calculations as collision rate parameters. However, there are no reported values for most of the radical intermediates in hydrocarbon combustion. In this work, a new group contribution formula was proposed and group contribution values of 40 groups for intermediates in the combustion of hydrocarbons were fitted from critical properties of 250 species, including 185 stable species with experimental critical property values and 65 radical species with calculated critical property values and these group contribution values were used to estimate critical properties for new species. 30 hydrocarbon compounds with available experimental properties were chosen to validate the accuracy of the model, the average absolute deviation of TC and PC were 8.52% and 16.83%, respectively, showing an agreement with experimental data. This model can predict critical properties for macromolecular and radical species. According to the empirical relations between critical properties and L-J parameters, L-J parameters of hydrocarbon combustion intermediates were estimated. It was shown that the predicted values for 46 compounds with available reported data were in good agreement with the reported values and the average absolute deviation of TC and PC were 9.88% and 9.96%, respectively. The L-J parameters of alkane radical ·C6H13, alkene radical ·C5H9 and alkyne radical ·C5H7 isomers were compared. L-J parameters of ·C6H13 and similar compound C6H14 were also compared and the results showed that there were obvious differences of the L-J parameters between isomers or between similar compounds. In addition, L-J parameters for 114 hydrocarbon radicals, for which L-J parameters had not been reported yet, were predicted. These data are important in the combustion modeling of hydrocarbons and pressure-dependent rate-coefficient calculations for elementary reactions in hydrocarbon combustion.

Key words: Lennard-Jones parameter, Critical property, Group contribution method, Radical group, Intermediate in hydrocarbon combustion

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