internal combustion

(noun)

The process where fuel is burned within an engine such as a diesel engine, producing power directly as opposed to externally such as in a steam engine.

Related Terms

Examples of internal combustion in the following topics:

  • Introduction to Provisioning

    • Wrights' powered flight depended on the existence of internal combustion engines, bicycles, fabric, gliders, metallurgy, and a host of other items.

  • Electric Generators

    • Possible sources of mechanical energy include: a reciprocating or turbine steam engine , water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, compressed air, or any other source of mechanical energy.

  • Energy Transformations

    • For example, an internal combustion engine converts the potential chemical energy in gasoline and oxygen into heat energy.

  • Industrial Societies: The Birth of the Machine

    • The First Industrial Revolution, which began in the 18th century, merged into the Second Industrial Revolution around 1850, when technological and economic progress gained momentum with the development of steam-powered ships, railways, and later in the 19th century with the internal combustion engine and electrical power generation.

  • Heat and Work

    • Scientists and engineers have been able to exploit the principles of thermochemistry to develop technologies ranging from hot/cold packs to gasoline powered combustion engines.
    • For a closed system, the change in internal energy (∆U) is related to heat (Q) and work (W) as follows:

  • Constant-Volume Calorimetry

    • Constant-volume calorimeters, such as bomb calorimeters, are used to measure the heat of combustion of a reaction.
    • A bomb calorimeter is a type of constant-volume calorimeter used to measure a particular reaction's heat of combustion.
    • where ΔU is the change in internal energy, and qV denotes the heat absorbed or released by the reaction measured under conditions of constant volume.
    • Thus, the total heat given off by the reaction is related to the change in internal energy (ΔU), not the change in enthalpy (ΔH) which is measured under conditions of constant pressure.
    • A schematic representation of a bomb calorimeter used for the measurement of heats of combustion.

  • Combustion Analysis

    • Combustion analysis is commonly used to analyze samples of unknown chemical formula.
    • One example of a simple combustion reaction is the combustion of methane:
    • Another common example of combustion is the burning of wood to produce thermal energy.
    • Combustion analysis can also be performed using a CHN analyzer, which uses gas chromatography to analyze the combustion products.
    • Energy is released in the form of flames as the fuel combusts.

  • Physical and Chemical Properties of Matter

    • Chemical properties cannot be determined just by viewing or touching the substance; the substance's internal structure must be affected for its chemical properties to be investigated.
    • Heat of combustion is the energy released when a compound undergoes complete combustion (burning) with oxygen.
    • The symbol for the heat of combustion is ΔHc.

  • Combustion

    • The combustion of carbon compounds, especially hydrocarbons, has been the most important source of heat energy for human civilizations throughout recorded history.
    • Precise heats of combustion measurements can provide useful iinformation about the structure of molecules.
    • From the previous discussion, we might expect isomers to have identical heats of combustion.
    • Thus, the heat of combustion of pentane is –782 kcal/mole, but that of its 2,2-dimethylpropane (neopentane) isomer is –777 kcal/mole.
    • The following table lists heat of combustion data for some simple cycloalkanes and compares these with the increase per CH2 unit for long chain alkanes.

  • Reaction Energetics

    • In the combustion of methane, for example, all six bonds in the reactant molecules are broken, and six new bonds are formed in the product molecules (equation 1).
    • Were this true, no life would exist on Earth, because the numerous carbon compounds that are present in and essential to all living organisms would spontaneously combust in the presence of oxygen to give carbon dioxide-a more stable carbon compound.
    • The combustion of methane (eq.1), for example, does not occur spontaneously, but requires an initiating energy in the form of a spark or flame.
    • Often it is heat, as noted above in reference to the flame or spark that initiates methane combustion.
    • At room temperature, indeed at any temperature above absolute zero, the molecules of a compound have a total energy that is a combination of translational (kinetic) energy, internal vibrational and rotational energies, as well as electronic and nuclear energies.