ME2100 Applied Thermal Engineering Tutorial – combustion
1. Calculate the theoretical air-fuel ratio on a mass and mole basis for the combustion of
ethanol, C2H5OH. [14.28, 8.943]
2. Methane is burned with 200% theoretical air at 1 atm. Find the composition and dew point of
the products. [XH2O = 0.0998, XCO2 = 0.0499, XN2 = 0.7505, XO2 = 0.0998, Tdp = 45.8 ˚C]
3. In a combustion process with decane, C 10H22, and air, the dry product mole fractions are
83.61% N2, 4.91% O2, 10.56% CO2 and 0.92% CO. Find the equivalence ratio and the
percent theoretical air of the reactants. [0.8, 125%]
4. A fuel, CxHy, is burned with dry air and the product composition is measured on a dry mole
basis to be: 9.6% CO2, 7.3% O2 and 83.1% N2. Find the fuel composition (x/y) and the percent
theoretical air used. [0.461, 149.3%]
5. A rigid vessel initially contains 2 kmol of carbon and 2 kmol of oxygen at 25°C, 200 kPa.
Combustion occurs, and the resulting products consist of 1 kmol of carbon dioxide, 1 kmol of
carbon monoxide, and excess oxygen at a temperature of 1000 K. Determine the final
pressure in the vessel and the heat transfer from the vessel during the process. [838.4 kPa, -
453442 kJ]
6. A closed rigid container contains propene, C 3H6, and 150% theoretical air at 100 kPa and 298
K. The mixture is ignited and complete combustion takes place. Heat is transferred to a
reservoir at 500 K so that the final temperature of the products is 700 K. Find the final
pressure, heat transfer per kmol fuel and the total entropy generated per kmol fuel. [238.4
kPa, -1.611×106 kJ/kmol-fuel, 4363.56 kJ/kmol-fuel-K]
7. Graphite, C, at pressure of p0 and 298 K, is burned adiabatically with air coming in at p 0, 500
K in a ratio such that the products exit at p 0, 1200 K. Find the equivalence ratio and the total
irreversibility. [3.535, 152425.659 kJ/kmol-fuel]
8. In a new high-efficiency furnace, natural gas, assumed to be 90% methane and 10% ethane
(by volume) and 110% theoretical air each enter at 25°C, 100 kPa, and the products
(assumed to be 100% gaseous) exit the furnace at 40°C, 100 kPa. What is the heat transfer
for this process? Compare this to an older furnace where the products exit at 250°C, 100 kPa.
[-859376.1 kJ/kmol-fuel, -778043.8 kJ/kmol-fuel]
9. Gaseous propane mixes with air, both supplied at 500 K, 0.1 MPa. The mixture goes into a
combustion chamber and products of combustion exit at 1300 K, 0.1 MPa. The products
analyzed on a dry basis are 11.42% CO 2, 0.79% CO, 2.68% O2, and 85.11% N2 on a volume
basis. Find the equivalence ratio and the heat transfer per kmol of fuel. [0.899, -1178502.8
kJ/kmol-fuel]
10. Wet biomass waste from a food-processing plant is fed to a catalytic reactor, where in a
steady flow process it is converted into a low-energy fuel gas suitable for firing the processing
plant boilers. The fuel gas has a composition of 50% methane, 45% carbon dioxide, and 5%
hydrogen on a volumetric basis. Determine the lower heating value of this fuel gas mixture
per unit volume. [16679.9 kJ/m3]
11. Hydrogen gas is burned with pure oxygen in a steady flow burner where both reactants are
supplied in a stoichiometric ratio at the reference pressure and temperature. What is the
adiabatic flame temperature? [4991 K]
12. Carbon is burned with air in a furnace with 150% theoretical air and both reactants are
supplied at the reference pressure and temperature. What is the adiabatic flame
temperature? [1833.9 K]
