Note: Assume the air composition by volume is 21%O2 and 79%N2. 1. Calculate the mass fractions of propane (C3H8) in the propane/air mixtures with equivalence ratios of = (a) 0.7 , (b) 1.0 , and (c) 1.3 . [12+12+12 points ] - If there is too much fuel in the mixture it is called a rich mixture. - If there is too much oxygen in the mixture it is called a lean mixture. - A rich or lean mixture will give "incomplete" combustion and the chemical heat released will be lower than stoichiometric combustion. - The ratio of the stoichiometric AFR to the actual AFR is called the equivalence ratio ( or ). =AFRactualAFRsoich=(mairmsuel)actual(mfuelmair)stoich