/25 Stabilized three-stage oxidation of gaseous n-heptane/air mixture in a micro flow reactor with a controlled temperature profile August 5, 2010 The 33rd International Symposium on Combustion Akira Yamamoto , Hiroshi Oshibe, Hisashi Nakamura, Takuya Tezuka, Susumu Hasegawa and Kaoru Maruta Institute of Fluid Science, Tohoku University (4C01)
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/25
Stabilized three-stage oxidation of gaseous
n-heptane/air mixture in a micro flow reactor
with a controlled temperature profile
August 5, 2010
The 33rd International Symposium on Combustion
Akira Yamamoto, Hiroshi Oshibe, Hisashi Nakamura,
Takuya Tezuka, Susumu Hasegawa and Kaoru Maruta
Institute of Fluid Science, Tohoku University
(4C01)
/25Institute of Fluid Science, Tohoku Univ. 2
It is important to know the ignition characteristics of various fuels.
Typical ignition process of practical hydrocarbon fuels
Time
Cool flame
Hot flame
Two-stage ignition at
different temperature range
BackgroundH
eat
rele
ase
rate
Cool flame
• Low temperature oxidation (LTO)
• Small heat release
Hot flame
• High temperature oxidation (HTO)
• Main heat release
Two-stage ignition phenomena strongly affect the combustion control.
⇒ Improvement of internal combustion engines.• Spark ignition engines
• Compression ignition (Diesel, HCCI) engines
• Gas turbines etc.
/25Institute of Fluid Science, Tohoku Univ. 3
Major approach: e.g., Rapid Compression Machines (RCMs)
Approaches to investigate the ignition characteristics
• Heat loss to chamber wall
• Roll-up vortices by piston motion
• Ignition in local spot → Propagation
Disparities with
the modeling that assumes
homogeneous combustion
Difficulties in RCM experiments…
Auto-ignition of methane/air mixture, Strozzi et al., CST 180 (2008)
Fuel/air
mixture
Rapid compression
Multi-zone/dimensional model should be required to reproduce the
experiments more accurately. But it needs higher computational cost.
/25Institute of Fluid Science, Tohoku Univ. 4
• Imposed wall-temperature profile in the flow direction
• Inner diameter of the tube < Ordinary quenching diameter
• Laminar flow (Re ≈ 1 ~ 100)
• Constant pressure
※Maruta et al., PCI 30, 32
Fuel/Air d < Quenching
diameter
x
Tw(x)
Test section0
Flame
External heat
Wall temperature profile
Quartz tube
Micro flow reactor with controlled temperature profile
/25Institute of Fluid Science, Tohoku Univ. 5
At extremely low velocity Gas-phase temperature ≒ wall temperature
※Maruta et al., PCI 30, 32
Fuel/Air d < Quenching
diameter
x
Tw(x)
Test section0
Flame
External heat
Wall temperature profile
Quartz tube
Micro flow reactor with controlled temperature profile
CH4/air, 1atm, U = 0.2 cm/s
Tsuboi et al., PCI 32
Stable weak flames exist at certain positions in temperature profile.
/25Institute of Fluid Science, Tohoku Univ. 6
Objectives
n-Heptane (n-C7H16)
– A basic liquid hydrocarbon fuel that shows typical multi-stage ignition
– One of the primary reference fuel of automotive gasoline
Investigate ignition and combustion characteristics of
gaseous n-heptane/air mixture using a micro flow reactor