Experimental and kinetic study of diisobutylene isomers in laminar flames

Abstract

Laminar flame speeds of 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene were studied at initial temperatures of 298–453 K, the equivalence ratios of 0.8–1.6 and initial pressure of 0.1 MPa. The comparison between 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene was also performed in this work. Results show that 2,4,4-trimethyl-2-pentene has faster laminar flame speeds than 2,4,4-trimethyl-1-pentene. The Metcalfe model was validated and modified, and the Modified model can give fairly good prediction at various conditions on laminar flame speeds of both 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene. In addition, the chemical kinetic analysis was conducted. The analysis indicates that the discrepancy of laminar flame speeds between two isomers mainly depends on the kinetic effects with the same adiabatic flame temperature. Furthermore, the kinetic analysis show that IC4H8 and DMPD13 are dominant intermediates of 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene, respectively. The transformation between IC4H8 and IC4H7 consumes various active radicals and has strong negative effect on the global activity, which results in lower mole fraction of H radical of 2,4,4-trimethyl-1-pentene compared with 2,4,4-trimethyl-2-pentene. Therefore, the latter has higher laminar flame speeds than the former. Sensitivity analysis showed that both of them are sensitive to small radical reactions. Besides, 2,4,4-trimethyl-1-pentene is sensitive to isobutene related reactions and 2,4,4-trimethyl-2-pentene is sensitive to DMPD13 related reactions.