Problem 2. For the hydrocarbon n-Nonane C9H20, (molar mass = 128.6 kg/kmol, enthalpy
formation = -274.7 kJ/mol, and enthalpy of vaporization = 295 kJ/kg at 298 K). Use the following
data
• Enthalpy of formation of H2O(g)=-241.83 kJ/kmol
• Enthalpy of formation of CO2=-393.52 kJ/kmol
• Latent heat of water vaporization hfg = 2.44 MJ/kg = 43.92 MJ/kmol
(a) Write balanced equations for lean and rich combustion, assuming suitable values of equivalence
ratio λ (3 marks)
(b) Determine the stoichiometric fuel-air ratio (FAR) (3 marks)
(c) Determine the Higher Heating Value (HHV) and Lower Heating Value (LHV) at 298 K
of n-Heptane (per kg) (6 marks)
(d) Determine the Higher Heating Value (HHV) and Lower Heating Value (LHV) for liquid
n-Heptane (per kg) (2 marks)
(e) Estimate the constant pressure Adiabatic Flame Temperature Tp for combustion. Use the
following assumptions:
• Complete combustion: the product mixture consists of only CO2, H2O, and N2.
• The enthalpy of the product mixture is estimated using constant specific heat, with an initial
guess for the temperature given by T = 1300 ≈ 0.5(Ti + Tp), where Tp is the constant
pressure Adiabatic Flame Temperature. (6 marks)
