1. ME 475/675 Introduction to Combustion
Lecture 9
Textbook’s computer programs: HPFLAME, TPEQUIL, Example 2.8

2. Announcements HW 3 due now Midterm 1
(two weeks from today)
HW 4 Due Monday, September 21, 2015
Ch 2 (33, 35, 47, 50, 54, 57, 63)
ABET PEV: Dr. Sriram Somasundaram at 9:30

3. Computer Programs Provided by Book Publisher
Described in Appendix F (pp 113-4)
For “complex” reactions (11 product species)
Fuel: CNHMOLNK
Oxidizer: Air
Download from web:
student edition
Computer codes
Access to TPEquil, HFFlame, UVFlame
Extract All

4. TPEQUIL (TP Equilibrium)
Use to find
Equilibrium composition and mixture properties
Required input
Fuel CNHMOLNK
Temperature
Pressure
Equivalence ratio (with air)
to determine initial number of moles of each atom

5. Input file
Equil. Calc. for Specified Fuel, Phi, T, & P Using Olikara/Borman Code
1 /NUMBER OF CARBON ATOMS IN FUEL MOLECULE
4 /NUMBER OF HYDROGEN ATOMS IN FUEL MOLECULE
0 /NUMBER OF OXYGEN ATOMS IN FUEL MOLECULE (NOT AIR)
0 /NUMBER OF NITROGEN ATOMS IN FUEL MOLECULE (NOT AIR)
.9 /EQUIVALENCE RATIO, PHI
/TEMPERATURE, T(K)
/PRESSURE, P(Pa)

6. Output File
The mole fractions of the product species are:
H: O: N:
H2: OH: CO:
NO: O2: H2O:
CO2: N2:
Above properties printed below in a column for cut & paste:
E+06
E+04
E+01
E+02
E-01
E-06
E-05
E-11
E-04
E-03
E-04
E-03
E-01
E+00
E-01
E+00
Equil. Calc. for Specified Fuel, Phi, T, & P Using Olikara/Borman Code
Data below are as read from the input file. Compare
with INPUT.TP. If they do not agree, your input
data have not been entered correctly.
CARBON ATOMS
HYDROGEN ATOMS
OXYGEN ATOMS
NITROGEN ATOMS
EQUIVALENCE RATIO
TEMPERATURE (K)
PRESSURE (Pa)
CALCULATED COMBUSTION PRODUCTS PROPERTIES
Mixture Enthalpy [J/kg] = E+06
Mixture Specific Heat, Cp [J/kg-K] = E+04
Specific Heat Ratio, Cp/Cv =
Mixture Molecular Weight [kg/kmol] =
Moles of Fuel per Mole of Products =

7. HPFLAME (HP Flame) Use to find Required Input
Adiabatic flame temperature for constant pressure
Required Input
Fuel, equivalence ratio, enthalpy of reactants HR, pressure
For constant pressure: HP = HR
Find TAd
In our initial examples we assume ideal combustion so we knew the product composition
But this program calculates the more realistic equilibrium composition of the products from a (complex) equilibrium calculation (multiple equilibrium reactions)
But this requires TProd = TAd, which we are trying to find!
Requires program (not humans) to iterate

8. Input File
Adiabatic Flame Calculation for Specified Fuel, Phi, P, & Reactant
Enthalpy Using Olikara & Borman Equilibrium Routines
Problem Title: USER SPECIFIES TITLE HERE
/CARBON ATOMS IN FUEL
/HYDROGEN ATOMS IN FUEL
/OXYGEN ATOMS IN FUEL
/NITROGEN ATOMS IN FUEL
/EQUIVALENCE RATIO
/TEMPERATURE (K) (Initial Guess)
/PRESSURE (Pa)
/ENTHALPY OF REACTANTS PER KMOL FUEL (kJ/kmol-fuel)

9. Output File The mole fractions of the product species are:
H: O: N:
H2: OH: CO:
NO: O2: H2O:
CO2: N2:
Above properties printed below in a column for cut & paste:
E+04
E+06
E+04
E+01
E+02
E+00
E-03
E-04
E-07
E-01
E-02
E-01
E-03
E-03
E+00
E-01
E+00
Adiabatic Flame Calculation for Specified Fuel, Phi, P, & Reactant
Enthalpy Using Olikara & Borman Equilibrium Routines
Problem Title: USER SPECIFIES TITLE HERE
Data below are as read from the input file. Compare
with INPUT.HP. If they do not agree, your input
data have not been entered correctly.
CARBON ATOMS
HYDROGEN ATOMS
OXYGEN ATOMS
NITROGEN ATOMS
EQUIVALENCE RATIO
TEMPERATURE (K) guess
PRESSURE (Pa)
ENTHALPY OF REACTANTS (kJ/kmol fuel)
FLAME TEMP. & COMBUSTION PRODUCTS PROPERTIES
Flame Temperature [K] =
Mixture Enthalpy [J/kg] = E+06
Mixture Specific Heat, Cp [J/kg-K] = E+04
Specific Heat Ratio, Cp/Cv =
Mixture Molecular Weight [kg/kmol] =
Moles of Fuel per Mole of Products =

10. Example 2.8, Page 54
A recuperator (heat exchanger) is employed in a natural-gas-fired heat-treating furnace. The furnace operates at atmospheric pressure with an equivalence ratio of The fuel gas enters the burner at 298 K, and the air is preheated.
(a) Determine the effect of air preheat on the adiabatic temperature of the flame zone for a range of inlet air temperatures from 298 to 1000 K.
(b) What fuel savings results from preheating the air from 298 to 600 K? Assume that the temperature of the flue gases at the furnace exit, prior to entering the recuperator, is K, both with and without air preheat.