An experimental and modeling study of iso-octane ignition delay times under homogeneous charge compression ignition conditions

• Published in: Combustion and flame Vol. 142; no. 3; pp. 266 - 275
• Main Authors: He, X., Donovan, M.T., Zigler, B.T., Palmer, T.R., Walton, S.M., Wooldridge, M.S., Atreya, A.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-08-2005; Elsevier Science
• Subjects: 10 SYNTHETIC FUELS; ALKANES; Applied sciences; Carbon dioxide; Charge; COMBUSTION KINETICS; Combustion of liquid fuels; Combustion. Flame; Compressing; Delay; Energy; Energy. Thermal use of fuels; Engines and turbines; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; HCCI; IGNITION; Ignition delay time; Iso-octane; Moles; PRESSURE RANGE MEGA PA 01-10; Rapid compression facility; TEMPERATURE RANGE 0400-1000 K; TEMPERATURE RANGE 1000-4000 K; Theoretical studies. Data and constants. Metering; TIME DEPENDENCE; Uncertainty; HCCI; Ignition delay time; Rapid compression facility; Iso-octane; Heat engine; Autoignition; Reaction mechanism; Combustion; Ignition delay; Isooctane; Performance
• ISSN: 0010-2180; 1556-2921
• DOI: 10.1016/j.combustflame.2005.02.014

Autoignition of iso-octane was examined using a rapid compression facility (RCF) with iso-octane, oxygen, nitrogen, and argon mixtures. The effects of typical homogeneous charge compression ignition (HCCI) conditions on the iso-octane ignition characteristics were studied. Experimental results for ignition delay times,
τ
ign, were obtained from pressure time-histories. The experiments were conducted over a range of equivalence ratios (
ϕ
=
0.25
–
1.0
), pressures
(
P
=
5.12
–
23

atm
)
, temperatures (
T
=
943
–
1027

K
), and oxygen mole fractions (
χ
O
2
=
9
–
21
%
), and with the addition of trace amounts of combustion product gases (CO
2 and H
2O). It was found that the ignition delay times were well represented by the expression
τ
ign
=
1.3
×
10
−4
P
−1.05
ϕ
−0.77
χ
O
2
−1.41
exp
(
33
,
700
/
R
(
cal
/
mol
/
K
)
T
)
,
where
P is pressure (atm),
T is temperature (K),
ϕ is the equivalence ratio (based on iso-octane to O
2 molar ratios),
χ
O
2
is the oxygen mole percent (%), and
τ
ign
is the ignition delay time (ms). Carbon dioxide was found to have no chemical effect on
τ
ign. Water was found to systematically decrease
τ
ign by a small amount (less than 14% for the range of conditions studied). The maximum uncertainty in the measured
τ
ign is ±12% with an average uncertainty of ±6%. The performance of several proposed chemical reaction mechanisms (including detailed, reduced, and skeletal mechanisms) was evaluated in the context of the current experimental results.