A spark-ignition engine is operated on isooctane fuel (C 8 H 10 ). The exhaust gases are cooled, dried to remove water, and then analyzed for CO 2 , CO, H 2 , 0,. Using the overall combustion reaction...

A spark-ignition engine is operated on isooctane fuel (C₈H₁₀). The exhaust gases are cooled, dried to remove water, and then analyzed for CO₂
, CO, H₂
, 0,. Using the overall combustion reaction for a range of equivalence ratios from 0.5 to 1.5, calculate the mole fractions of CO₂, CO, H­₂, and 0, in the dry exhaust gas, and plot the results as a function of equivalence ratio. Assume:

(a) that all the fuel is burnt inside the engine (almost true) and that the r'atio of moles CO to moles H, in the exhaust is 3 : 1, and

(b) that there is no hydrogen in the exhaust for lean mixtures.

For high-power engine operation the airlfuel ratio is 14 : 1. What is the exhaust gas composition, in mole fractions, before the water is removed?