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• The ignition timing is much less sensitive to changes in speed and load than that of two-
stage ignition fuel, which indicates that significantly less compensation will be required
to maintain optimal ignition timing over the required load and speed range.
• Advantages of two-stage ignition fuel for HCCI engine
• Because the amount of LTHR produced by a two-stage ignition fuel increases with the
local fuel/air equivalence ratio (Ï•), fuel stratification can be used for controlling combus-
tion phasing.
• This local ϕ-dependence of the LTHR also provides a means for reducing the peak HRR.
For this work, methane and iso-octane are selected as the single-stage ignition fuel, and DME
and n-heptane are selected as the two-stage ignition fuel. Methane and DME are classified
as a gaseous fuel. On the other hand, iso-octane and n-heptane are classified as a liquid fuel.
Figure 2 presents the chemical formula and the illustration of chemical structure, and Table 1
lists the properties for these four test fuels [15, 16].
2.3. Chemical-kinetic mechanism for test fuels
An overall reaction includes very complex and sophisticated reactions that cannot be ana-
lyzed without a proposed chemical-kinetic mechanism, a series of steps that a reaction takes
before reaching the final products. The chemical-kinetic mechanism is step-by-step descrip-
tions of what happens on a molecular level in chemical reactions. Each step of the reaction
mechanism for the overall reaction is known an elementary reaction. The term elementary
reaction is used to describe a moment in the reaction when one or more molecules change
geometry or perturbed by the addition or omission of another interacting molecule. For
methane and DME, a detailed chemical-kinetic mechanism (Mech_56.54; 113 species and 710
reactions) by Burke et al. [17] was used, which has been developed to be capable of predict-
ing the combustion of both methane and DME in common combustion environments such
as compression ignition engines and gas turbines. For iso-octane and n-heptane, a detailed
Figure 2. Chemical formula and illustration of chemical structure with reaction mechanism for methane, DME, n-heptane
and iso-octane.
Advanced Chemical
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Advanced Chemical Kinetics
- Title
- Advanced Chemical Kinetics
- Author
- Muhammad Akhyar Farrukh
- Editor
- InTech
- Location
- Rijeka
- Date
- 2018
- Language
- English
- License
- CC BY 4.0
- ISBN
- 978-953-51-3816-7
- Size
- 18.0 x 26.0 cm
- Pages
- 226
- Keywords
- Engineering and Technology, Chemistry, Physical Chemistry, Chemical Kinetics
- Categories
- Naturwissenschaften Chemie