Question

What is the formulae used for calculating the theoretical amount of weight of air required for combustion?

(a) Air required = 100/21[(32/12) × C + 8 × (H – O/8) + S] kg

(b) Air required = 100/23[(32/12) × C + 8 × (H – O/8) + S] kg

(c) Air required = 100/23[(32/12) × C – 8 × (H – O/8) + S] kg

(d) Air required = 100/21[(32/12) × C – 8 × (H – O/8) + S] kg

I got this question during an internship interview.

Question is from Numerical Problems Based on Combustion and Fuel Gas Analysis in chapter Fuels and Combustion of Engineering Chemistry II

Answer 1

Correct answer is (b) Air required = 100/23[(32/12) × C + 8 × (H – O/8) + S] kg

The explanation is: For complete combustion of 1 kg of solid or liquid fuel, the theoretical amount of air required is

        Air required = 100/23[(32/12) × C + 8 × (H – O/8) + S] kg

For volume the percentile is taken as 100/21.