Shock tube combustion of liquid hydrocarbon sprays of toluene

The liquid spray combustion of toluene has been studied in shock waves at temperatures between 900 and 2000 K and pressures up to 20 bar in oxygen–argon mixtures. The ignition delays were found to be dependent on the pressure and or fuel/oxygen ratio and the presence of up to 10% of additive. Two types of combustion were found: Type I occurred at lower temperatures and gave a steady combustion where the pressure rose steadily. Type II was detected at higher temperatures and in the presence of certain additives and gave a very sharp ‘spiked’ pressure rise. This phenomenon may be due to the occurrence of small droplet explosions or microcombustions and is similar to that of ‘knock’ in engines. The effect of additives on the ignition delay time depended on both the additive used and the concentration. 1% DTBP (di-tert-butyl peroxide) in the toluene has little effect on the ignition delay but 10% DTBP reduced it a little. 5% IPN (isopropyl nitrate) and EHN (ethyl hexyl nitrate) both had a neglible effect on the ignition time in this temperature region. IPN was also found to affect the type of combustion, changing it from Type I to Type II.

[1]  H. O. Pritchard,et al.  Retardation of spontaneous hydrocarbon ignition in diesel engines by di-tert-butyl peroxide , 2000 .

[2]  G. Adomeit,et al.  Self-ignition of S.I. engine model fuels: A shock tube investigation at high pressure ☆ , 1997 .

[3]  H. O. Pritchard,et al.  Stimulation of diesel-fuel ignition by benzyl radicals☆ , 1995 .

[4]  M. Poirier,et al.  Synergy between additives in stimulating diesel-fuel ignition , 1993 .

[5]  D. J. Rose,et al.  Fundamental features of hydrocarbon autoignition in a rapid compression machine , 1993 .

[6]  H. Ciezki,et al.  Shock-tube investigation of self-ignition of n-heptane - Air mixtures under engine relevant conditions , 1993 .

[7]  J. Griffiths,et al.  Experimental and numerical studies of the combustion of ditertiary butyl peroxide in the presence of oxygen at low pressures in a mechanically stirred closed vessel , 1990 .

[8]  H. O. Pritchard,et al.  Effect of free-radical release on diesel ignition delay under simulated cold-starting conditions , 1990 .

[9]  H. Pritchard.  Thermal decomposition of isooctyl nitrate , 1989 .

[10]  Hideharu Ehara,et al.  Effect of exhaust gas recirculation on diesel knock intensity and its mechanism , 1988 .

[11]  R. Summers,et al.  Studies of fuel injection into a rapid compression machine , 1981 .

[12]  L. Kirsch,et al.  The autoignition of hydrocarbon fuels at high temperatures and pressures—Fitting of a mathematical model , 1977 .

[13]  A. K. Oppenheim,et al.  Auto-ignition of hydrocarbons behind reflected shock waves , 1972 .

[14]  C. G. McCreath,et al.  The effect of fuel additives on the exhaust emissions from diesel engines , 1971 .

[15]  G. Mullaney.  Autoignition of Liquid Fuel Sprays , 1959 .