Fuel property definition: The amount of heat released by the complete combustion of 1 kg of a fuel is called what?

Introduction / Context:
Calorific value (heating value) is a fundamental property used to size burners, boilers, and engines, and to estimate emissions per unit of energy delivered. It is defined per unit mass for solid and liquid fuels and per unit volume or mole for gaseous fuels.

Given Data / Assumptions:

• Combustion is complete, with products cooled to a reference state.
• Basis: 1 kg of fuel for solids/liquids.
• Two conventions exist: higher and lower heating values.

Concept / Approach:
The general term “calorific value” refers to the heat released by complete combustion per kilogram of fuel. Subtypes include Higher Calorific Value (HHV), which assumes water in products is condensed (latent heat recovered), and Lower Calorific Value (LCV/LHV), which assumes water remains vapor (latent heat not recovered). Both are specific cases of the broader “calorific value.”

Step-by-Step Solution:

Verification / Alternative check:
Laboratory bomb calorimeter tests measure HHV directly; LHV is computed by subtracting the latent heat of vaporization corresponding to the formed water.

Why Other Options Are Wrong:

• Heat energy: Vague; not a property name.
• Lower calorific value / higher calorific value: These are specific variants, not the general definition asked.

Common Pitfalls:
Comparing fuels using mixed bases (wet vs dry, HHV vs LHV) without conversion; misinterpreting volumetric values of gases as directly comparable to mass-based values of solids.

Final Answer:
calorific value