5310: Combustion Fundamentals
Homework #2
STANJAN or NASA CEA Practice Problem:
Consider combustion of a methane-air mixture at 10 atm (both fuel and air are at 10 atm).
a.
Plot mole fractions,
χ
i
, for the species CO
2
, CO, H
2
O, H
2
, OH, O
2
, N
2
, NO vs.
temperature for
φ
=1 for a temperature range from 1,000 to 2,500 K.
b.
Calculate T
flame
and mole fractions as a function of
φ
for adiabatic combustion. Plot these
results vs.
φ
and discuss at what value the peak flame temperature occurs. Comment on
this value in light of the discussion found in Chapter 1, Part 2 of Glassman.
c.
Compare T
flame
from part (2) to what would be obtained assuming complete oxidation
(burning in only oxygen) and what would be obtained assuming complete combustion
(burning in air).
Problems from Turns:
Complete questions: 4-6, 4-7, 4-10, 4-11, 4-12, 4-13, 4-16, 4-17, 4-20
Problems (these problems are from Glassman Chapter 2):
1:
For a temperature of 1,000 K, calculate the pre-exponential factor in the specific reaction rate
constant for:
1.
any simple bimolecular reaction
2.
any simple unimolecular decomposition reaction following transition state theory.
Complete this problem using the collision model described in Section B, part 1. To complete this
problem it will be necessary to estimate the average molecular diameter, d
2
AB
using a simple
kinetic theory approach for viscosity assuming a Maxwellian distribution:
2
2
1
1
d
mkT
π
μ
=
1.1
Also note that
μ
AB
(the reduced mass, not the viscosity as given above) can be approximated as
30. Note that this problem can also be completed using reaction rate theory for reactions between