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Energy conversion efficiency (η) is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The input, as well as the useful output may be chemical , electric power , mechanical work , light (radiation), or heat .
Since this is a measurement of mass, any conversion to barrels of oil equivalent depends on the density of the oil in question, as well as the energy content. Typically 1 tonne of oil has a volume of 1.08 to 1.19 cubic metres (6.8 to 7.5 bbl).
In battery or electric vehicles, calculating the vehicle's overall efficiency of useful work begins with the charge–discharge rate of the battery pack, generally 80% to 90%. Next is the conversion of stored energy to distance traveled under power.
The unit of energy consumed is deemed to be 33.7 kilowatt-hours without regard to the efficiency of conversion of heat energy into electrical energy, also measured in kilowatt-hours (kWh). The equivalence of this unit to energy in a gallon of gasoline is true if and only if the heat engine, generating equipment, and power delivery to the car ...
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 .
Mass–energy equivalence states that all objects having mass, or massive objects, have a corresponding intrinsic energy, even when they are stationary.In the rest frame of an object, where by definition it is motionless and so has no momentum, the mass and energy are equal or they differ only by a constant factor, the speed of light squared (c 2).
In general, energy conversion efficiency is the ratio between the useful output of a device and the input, in energy terms. For thermal efficiency, the input, Q i n {\displaystyle Q_{\rm {in}}} , to the device is heat , or the heat-content of a fuel that is consumed.
The energy factor metric only applies to residential water heaters, which are currently defined by fuel, type, and input capacity. [5] Generally, the EF number represents the thermal efficiency of the water heater as a percentage, since it is an average of the ratio of the theoretical heat required to raise the temperature of water drawn to the amount of energy actually consumed by the water ...