Are you an EPFL student looking for a semester project?
Work with us on data science and visualisation projects, and deploy your project as an app on top of Graph Search.
Concept
Heat of combustion
Summary
The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it.
The calorific value is the total energy released as heat when a substance undergoes complete combustion with oxygen under standard conditions. The chemical reaction is typically a hydrocarbon or other organic molecule reacting with oxygen to form carbon dioxide and water and release heat. It may be expressed with the quantities:
energy/mole of fuel
energy/mass of fuel
energy/volume of the fuel
There are two kinds of enthalpy of combustion, called high(er) and low(er) heat(ing) value, depending on how much the products are allowed to cool and whether compounds like H2O are allowed to condense.
The high heat values are conventionally measured with a bomb calorimeter. Low heat values are calculated from high heat value test data. They may also be calculated as the difference between the heat of formation ΔH of the products and reactants (though this approach is somewhat artificial since most heats of formation are typically calculated from measured heats of combustion).
By convention, the (higher) heat of combustion is defined to be the heat released for the complete combustion of a compound in its standard state to form stable products in their standard states: hydrogen is converted to water (in its liquid state), carbon is converted to carbon dioxide gas, and nitrogen is converted to nitrogen gas. That is, the heat of combustion, ΔH°comb, is the heat of reaction of the following process:
CcHhNnOo (std.) + (c + - ) O2 (g) → cCO2 (g) + H2O (l) + N2 (g)
Chlorine and sulfur are not quite standardized; they are usually assumed to convert to hydrogen chloride gas and SO2 or SO3 gas, respectively, or to dilute aqueous hydrochloric and sulfuric acids, respectively, when the combustion is conducted in a bomb calorimeter containing some quantity of water.
Zwolinski and Wilhoit defined, in 1972, "gross" and "net" values for heats of combustion.
Official source
About this result
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
Ontological neighbourhood
Related courses (10)
ME-409: Energy conversion and renewable energy
This course presents an overview of (i) the current energy system and uses (ii) the main principles of conventional and renewable energy technologies and (iii) the most important parameters that defin
ChE-201: Introduction to chemical engineering
Introduction to Chemical Engineering is an introductory course that provides a basic overview of the chemical engineering field. It addresses the formulation and solution of material and energy balanc
ME-551: Engines and fuel cells
The students describe and explain the thermodynamic and operating principles of internal combustion engines and all fuel cell types, identify the determining physical parameters for the operating regi
Related lectures (35)
Biomass Energy Content: TVN
Discusses the energy content of biomass compared to fossil fuels and the differences in various biomass feeds.
Heat Exchange and Psychrometric Diagrams
Explores heat exchange, psychrometric diagrams, and the importance of latent heat.
Combustion: Fundamentals and Applications
Explores combustion fundamentals, heat sources, fuel origins, environmental impact, fuel composition, boiler efficiency, and heat recovery.
Related publications (63)
Related people (23)
Related units (4)
Related concepts (35)
Methane
Methane (USˈmɛθeɪn , UKˈmiːθeɪn ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it poses technical challenges due to its gaseous state under normal conditions for temperature and pressure. Naturally occurring methane is found both below ground and under the seafloor and is formed by both geological and biological processes.
Fuel
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but has since also been applied to other sources of heat energy, such as nuclear energy (via nuclear fission and nuclear fusion). The heat energy released by reactions of fuels can be converted into mechanical energy via a heat engine.
Chemical energy
Chemical energy is the energy of chemical substances that is released when the substances undergo a chemical reaction and transform into other substances. Some examples of storage media of chemical energy include batteries, food, and gasoline (as well as oxygen gas, which is of high chemical energy due to its relatively weak double bond and indispensable for chemical-energy release in gasoline combustion). Breaking and re-making chemical bonds involves energy, which may be either absorbed by or evolved from a chemical system.