Question

Which of the following is the expression for determination of calorific value of coal using Davies formulae? (where CV is calorific value, %H is percentage of hydrogen, %C is percentage of carbon, %O is percentage of oxygen and %S is percentage of sulphur.)

(a) CV = (6.543×%H + 403)[%C/3 + %H – (%O – %S)/8]

(b) CV = (6.543×%H + 403)[%C/3 + %H + (%O – %S)/8]

(c) CV = (6.543×%H – 403)[%C/3 + %H – (%O – %S)/8]

(d) CV = (6.543×%H – 403)[%C/3 + %H + (%O – %S)/8]

I have been asked this question during an internship interview.

This key question is from Coal in chapter Fuels and Combustion of Engineering Chemistry II

Answer 1

Right choice is (a) CV = (6.543×%H + 403)[%C/3 + %H – (%O – %S)/8]

Easy explanation: This formulae is based on ultimate analysis of fuel. The calorific value calculated here is expressed in B.Th.U./lb. Here we have only one calorific value not such as the Dulong’s formulae where we have GCV and NCV.