Combustion. Energy conversion efficiency
Combustion is defined as the burning of a fuel and oxidant to produce heat and/or work. It is the
majorenergy release mechanism in the Earth and key to humankind's existence. Combustion includes thermal,
hydrodynamic, and chemical processes. It starts with the mixing of fuel and oxidant, and sometimes in the
presence of other species or catalysts. The fuel can be gaseous, liquid, or solid and the mixture may be ignited
with a heat source. When ignited, chemical reactions of fuel and oxidant take place and the heat release from
the reaction creates a self-sustained process. The combustion products include heat, light, chemical species,
pollutants, mechanical work, and plasma. Sometimes, a low-grade fuel, e.g., coal, biomass, or coke, can be
partially burned to produce higher-grade fuel, e.g., methane. The partial burning process is called gasification.
Various combustion systems, e.g., furnaces, combustors, boilers, reactors, and engines, are developed to
utilize combustion heat, chemical species, and work.
Combu
Combustion Cycle
Advanced measurement and control equipment has traditionally been used as a tool for the analysis of a
combustion system. The analysis can lead to lower energy use and pollutant emissions by the system.
Recently, the computational codes, including kinetics and fluid dynamics codes, have been used as an added
tool for combustion analysis. In recent years, concerns over the availability of energy sources and the impacts
of combustion processes on global environments, have attracted more and more attention; this concern has
been heightened with recognition that fossil fuels have a finite supply. Thus, efficient and responsive use of
our energy sources has become a primary concern for human society.
Heat of combustion
The heat of combustion (Q) is the energy released as heat when a compound undergoes complete
combustion with oxygen under standard conditions. The chemical reaction is typically a hydrocarbon reacting
with oxygen to form carbon dioxide, water and heat. It may be expressed with the quantities:
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energy/mole of fuel (J/mol)
energy/mass of fuel
energy/volume of fuel
The heat of combustion is traditionally measured with a bomb calorimeter.
It may also be calculated as the difference between the heat of formation of
the products and reactants.
Energy conversion efficiency
Energy conversion efficiency is the ratio between the useful output of
an energy conversion machine and the input, in energy terms. The useful
output may be electric power, mechanical work, or heat. Energy conversion
efficiency is not defined uniquely, but instead depends on the usefulness of
the output.
Generally, energy conversion efficiency is a dimensionless number between 0 and 1.0, or 0 to 100%.
Efficiencies may not exceed 100%, e.g., for a perpetual motion machine. However, other effectiveness
measures that can exceed 1.0 are used for heat pumps and other devices that move heat rather than convert it.
Related, more specific terms include
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Electrical efficiency, useful power output per electrical power consumed;
Mechanical efficiency, where one form of mechanical energy (e.g. potential energy of water) is converted
to mechanical energy (work);
 Thermal efficiency useful heat and/or work output per input energy such as the fuel consumed;
http://en.wikipedia.org/wiki/Heat_of_combustion
http://en.wikipedia.org/wiki/Energy_conversion_efficiency
combustion – згоряння
fuel – паливо
light – світло
flame – полум’я
compound – сполука
water vapor – водяна пара
soot – сажа
useful output – корисна продукція
dimensionless number – безрозмірне число
burning - горіння
heat - теплота
glowing – ярко світній, палаючий
liquid - рідина
rocket engines – ракетний двигун
carbon monoxide – чадний газ
energy conversion efficiency - ККД
waste heat – відпрацьована теплота
combustion engine - ДВЗ