Question

2) (14 pts) Write the balanced reaction equation for the stoichiometric, complete combustion of propane, C3H8, in air. Determine (a) the mass and mole fractions of fuel, oxygen, and nitrogen in the reactants, (b) the mass and mole fractions of carbon dioxide, water vapor, and nitrogen in the combustion products, (c) the stoichiometric air-fuel ratio and the air-fuel ratio for 30% excess air, (d) the adiabatic flame temperature for stoichiometric conditions and for 30% excess air, (e) calculate the heating values (LHV and HHV) for stoichiometric conditions and 30% excess air.

Note: Do not use any HHV values listed in a table. Calculate your own value but feel free to use a listed value as a sanity check!

Please show all work and use the tables provided

Answer 1

Stoichiometric equation for complete combustion of propane: - C_3 H_8 + 5O_2 rightarrow 3 CO_2 + 4 H_2 O Let initial propane = 100 mol So O_2 required = 500 mol for complete combustion As air contains 21 % oxygen and 79 % Nitrogen 21 % of air = 500 moles of air = 500 times 100/21 = 2380/952 moles moles of nitrogen = 79 % of 2380.952 = 1880.952 mol mass of propane = 100 times 44 = 4400 g mass of O_2 = 500 times 32 = 16000 g mass of N_2 = 1880.952 times = 52666.656 g a) mass ratio C_3 H_8: O_2: N_2 = 4400: 16000: 52666.656 = 1: 3.6364: 11.9697 mole ratio = 100: 500: 2380.952 = 1: 5: 23.8096 b) CO_2 formed = 300 mol, mass = 300 times 44 = 13200 g H_2 O formed = 400 mol mass = 400 times 18

Adiabatic flame temperature is the maximum temperature reached in the fuel reactor, from complete combustion of fuel.

First four parts are done in the solution as per the rules, if nothing is mentioned first four parts are done, if you want the fifth part too, you are free to comment.