Heating value (or calorific value) is used to define the amount of heat released during the combustion of a fuel or food. It is measured in units of energy per amount of material. Depending on the context, heating values may be reported as Btu/m^3 , kcal/kg, J/mol, or a variety of other combinations of units. Heating value in commonly determined by use of a bomb calorimeter. A red-hot iron rod cooling after being worked by a blacksmith. ... For the workstation, see SGI Fuel. ... The British thermal unit (BTU or Btu) is a non-metric unit of energy, used in the United States and, to a lesser extent, the UK (where it is generally only used for heating systems). ... KCAL-TV (Channel 9) is an independent station in Los Angeles, California. ... A calorimeter is a device used for calorimetry, the science of measuring the heat of chemical reactions or physical changes. ...

The quantity known as higher heating value (or gross calorific value or gross energy) is determined by bringing all the products of combustion back to the original pre-combustion temperature. The quantity known as lower heating value (or net calorific value) is determined by subtracting the heat of vaporization of the water in the by-product from the higher heating value results. The lower heating value is what is typically used for vehicle engine analysis. The Higher Heating Value (HHV) of a fuel is defined as the amount of heat released by a specified quantity (initially at 25°C) once it is combusted and the reactants have returned to a temperature of 25°C. The Higher Heating Value takes into account the latent heat of... The Lower Heating Value (LHV) of a fuel is defined as the amount of heat released by combusting a specified quantity (initially at 25°C) and returning the temperature of the combustion products to 150°C. The Lower Heating Value assumes the latent heat of vaporization of water in the... The heat of vaporization is a physical property of substances. ... An engine is something that produces some effect from a given input. ...

Since most gas burning appliances cannot utilize the heat content of the water vapor, gross calorific value is of little interest. Fuel should be compared based on the net calorific value. This is especially true for natural gas, since increased hydrogen content results in high water formation during combustion. General Name, Symbol, Number Hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1 (IA), 1, s Density, Hardness 0. ...

See also:

• Wobbe index