Beginner Topic 398 of 1102 Thermodynamics & Energetics
Fuel Calorific Value
The heat released per gram or mole of fuel burned.
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In-depth explanation of Fuel Calorific Value
The calorific value of a fuel is the heat released when a unit mass or volume of it is completely burned, usually expressed in kilojoules per gram or megajoules per kilogram. It indicates how much useful energy can be obtained from a given quantity of fuel. Fuels rich in hydrogen and low in oxygen tend to have higher calorific values per unit mass, because hydrogen combustion releases a large amount of energy per gram and any oxygen already in the fuel contributes no energy. Calorific value is measured with a bomb calorimeter, and it is reported as gross or net depending on whether the water formed on combustion is condensed. This value is the basic metric for comparing fuels.
Going deeper: Fuel Calorific Value
Key ideas: Net value excludes the latent heat of water vapor, and gross value includes it. Calculate from a bomb calorimeter or from combustion enthalpies divided by molar mass. Compare per kilogram for transport and per litre for tank volume.
Common mistakes and connections: Mixing up gross and net values gives differences of about five to ten percent. High calorific value alone does not make a good fuel, since safety, storage, cost and emissions also matter. The value connects to combustion enthalpy and energy density.
Visualization of Fuel Calorific Value
Calorific values per kilogram. Hydrogen is highest by mass; wood and coal carry far less energy per kg. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Hydrogen has a calorific value of about 142 megajoules per kilogram, roughly three times that of gasoline at about 46 megajoules per kilogram.
Frequently asked questions about Fuel Calorific Value
What is Fuel Calorific Value?
The heat released per gram or mole of fuel burned.
Is Fuel Calorific Value a beginner, intermediate or advanced topic?
Fuel Calorific Value is a beginner topic in Thermodynamics & Energetics. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Fuel Calorific Value?
Study these earlier topics in Thermodynamics & Energetics first: Gibbs Phase Rule, Clapeyron Equation, Thermodynamic vs Kinetic Control.
What comes after Fuel Calorific Value?
The next topics in Thermodynamics & Energetics are Energy Density and Fossil Fuels.
Can I practise Fuel Calorific Value with quizzes?
Yes. The interactive lesson includes a self-check question on Fuel Calorific Value, and the Thermodynamics & Energetics quiz draws on every topic in this area.
Where Fuel Calorific Value fits in Thermodynamics & Energetics
Fuel Calorific Value is topic 70 of 91 in Thermodynamics & Energetics.