Mechanical Engineering - Thermodynamics - Discussion

Calorific value is defined as the amount of heat energy produced on complete combustion of 1 kilogram of fuel. The higher the calorific value of a fuel, the more is its efficiency. The calorific value of gaseous fuels is more. When gaseous fuel burns, it gives off a great deal of energy.

Gaseous fuels have higher calorific values because of the following reasons.

There remains no unburnt waste in gaseous fuels, unlike solid and liquid fuels.

Whether solid or liquid, combustion occurs when a volatile solid of liquid under high temperature converts to gas, so some energy is wasted to get the solid and liquid converted into gas. This loss is not there in gaseous fuels.

Solid fuels have a higher calorific value than liquid fuels - This is an incorrect statement because liquid fuels have a higher calorific value than solid fuels.

Hence, option C is the correct answer.

Liquid Fuels have higher calorific value compared to solid fuels per unit mass because solid fuels contain moisture and unwanted materials that's why they produce ash after combustion.

Petrol has higher calorific value 44000kj/kg but solid fuels has lesser C.V than petrol. Either gas fuels has also less C.V than petrol.

Liquid fuel has higher calorific value compared to solid fuel cause solid contained some air, moisture and dust.

Which of the following is "INCORRECT" Incorrect not correct. Therefore option (c) is answer.

For gases c.v. is 11- 20, solids c.v. is 35- 37 and for liquids c.v. is 43-47 for most of the fuels.

Correct Answer is Opt. B. Liquid fuels have higher calorific value than solid fuels.

Options B is correct, i.e. Liquid fuel have higher calorific value than solid fuel.

Liquids have lower bond energy and thus have higher calorific value.