3 Oxidation mechanisms of fuels Flashcards
Characteristics of Alkanes (Paraffins)
- C(m)H(2m+2)
- single-bond
What’s the smallest alkane?
CH4, methane
Which is the major component of natural gas?
Methane
Which fuels have C(m)H(2m)?
- Cycloalkanes
- Alkanes (Olefins)
Characteristics of Cycloalkanes
- C(m)H(2m)
- single-bond
- ring structured
Characteristics of Alkenes
- C(m)H(2m)
- 1 double bond, rest single bond
Characteristics of Polyolefins
- C(m)H(2m-2(n-1))
- more than one double bond
Characteristics of Alkynes (Acetylenes)
- C(m)H(2m-2)
- 1 triple bond
Characteristics of Aromatics
- ring-structured
- ring contains 6 carbon atoms
Name some aromatics
- Benzene (C6H6)
- Naphtalene (C10H8)
- Biphenyl (C12H10)
Do Alcohols (R-OH) or Hydrocarbons (R-H) have higher heats of comubtions?
Alcohols have lower heats of combustion
Name other important fuels
- Ammonium perchlorate
- Hydrazine
Which initiation reactions are possible for a H2-O2 system?
- Dissociation of H2 (at high T)
- Dissociation of O2
- Reaction between H2 and O2
Which are the major species in a H2-O2 system?
H2
O2
H2O
Which are the minor species in a H2-O2 system?
H O OH OH2 H2O2
Why is it difficult to sustain a dry CO-O2 flame?
Beause the reaction between CO and O2 has
a high actigation energy and is a very slow process
even at high temperatures.
Why isn’t it possible to sustain CO/O2 flames in the laboratory?
The oxidation of CO is a high activation energy reaction with
low heat release that
cannot sustain its forward progress.
Which are the two most important reactions in a comubstion process of hydrocarbon oxidation?
H + O2 -> O + OH
CO OH -> CO2 + H
What’s the main chain-branching reaction?
H + O2 -> O + OH
This reaction has a large activation energy.
Features of chain branching reactions
- endothermic
- large activation energy
- sensitive to pressure
