15–14 Propane fuel (C3H8) is burned in the presence of air. Assuming that the combustion is theoretical—that is, only nitrogen (N2), water vapor (H2O), and carbon dioxide (CO2) are present in the products—determine (a) the mass fraction of carbon dioxide and (b) the mole and mass fractions of the water vapor in the products.
15–16 Acetylene (C2H2) is burned with 25 percent excess oxygen in a cutting torch. Determine the mass fraction of each of the products. Calculate the mass of oxygen used per unit mass of acetylene burned.
15–20 One kmol of ethane (C2H6) is burned with an unknown amount of air during a combustion process. An analysis of the combustion products reveals that the combustion is complete, and there are 3 kmol of free O2 in the products. Determine (a) the air–fuel ratio and (b) the percentage of theoretical air used during this process.