Standard Fuel Calorific Values
In physical chemistry, a calorific value or calorific power is a measure of the energy released when a fuel is burned. It is measured either in joules per kilogram (J/kg) or megajoules per kilogram (MJ/kg) and is sometimes referred to as thermal effeciency.
Calorific value is an important factor for determining fuel prices since more energy denser fuels such as diesel, gasoline and jet fuel generally require less volume to provide the same energy output. It is also important to consider combustion efficiency, which is the ratio of energy input to energy output during complete combustion of the fuel.
Standard calorific value (SCV) is a measurement used to compare the energy content of different fuels. It is defined as the heat energy produced during complete combustion of a fuel when the product is water vapour and carbon dioxide. This can be calculated as the sum of the heat of combustion and the latent heat of vaporization of water.
A comparison of the standard calorific values of a range of common liquid fuels can provide an indication of the relative energy content of different fuels. The following table presents a summary of the SCV of a range of common liquid fuels:
Fuel S.C.V. (MJ/kg)
Diesel 42.6
Gasoline 44.7
Jet fuel 43.7
Kerosene 43.5
Biodiesel 38.5
Ethanol 31.0
Methanol 23.7
It is important to note that the SCV can vary between fuels of the same type. This is due to the different chemical composition of each fuel, as well as factors such as water content and the presences of impurities. Therefore, the SCV may vary between samples of the same fuel type.
In addition to the SCV, other factors such as flash point, boiling point and viscosity also affect the combustion and performance of a fuel. The flash point is the temperature at which vapors will form and cause the fuel to ignite and combust, while the boiling point is the temperature at which the liquid fuel will boil and evaporate. Viscosity is a measure of the resistance of a liquid fuel to flow and is an important factor for diesel engines where it affects atomization in the combustion chamber and fuel delivery.
In summary, standard calorific value is an important metric for comparing the energy content of different fuels. It is also important to consider other parameters such as flash point, boiling point and viscosity when selecting a fuel for an application. Knowledge of these parameters can help to ensure an efficient combustion process and optimize fuel performance.
