The calorific value refers to the heat generated by the combustion of a unit mass of fuel, which is an important indicator for evaluating the quality of the fuel. The unit is expressed in megajoules/kg (MJ/kg). The average low calorific value is 41.87 MJ/kg for oil, 38.97 MJ/kg for natural gas, and 20.93 MJ/kg for raw coal. Internationally, it is mostly measured by the base calorific value (standard coal equivalent) of 29.27 MJ/kg for standard fuel applications. The standard fuel coefficients for oil and natural gas conversion are 1.4286 and 1.33, respectively.
Test method The calorific value is determined by burning a weighed sample with an oxygen bomb calorimeter under controlled conditions. It is calculated by observing the temperatures before, during and after combustion with appropriate thermochemical and heat transfer corrections