The heating value Hi (formerly lower heating value Hu) is the maximum usable amount of heat during combustion at which no condensation of the water vapor contained in the exhaust gas occurs, in relation to the amount of fuel used. The calorific value is therefore the measure of the specific amount of heat that can be used per rated unit without condensation heat.
The calorific value Hs (outdated calorific value or upper calorific value Ho) is a measure of the specific thermal energy contained in a substance per rated unit. The calorific value of a fuel indicates the amount of heat that is released during combustion and subsequent cooling of the combustion gases to 25 °C and their condensation.The calorific value takes into account both the energy required to heat the combustion air and the exhaust gases as well as the heat of vaporization or condensation of liquids, especially water.
In contrast to the calorific value, the heating value describes the amount of heat that is released during combustion and subsequent cooling to the initial temperature of the combustible mixture, whereby the combustion water is still in the form of vapor. The calorific value of water-rich fuels is therefore significantly lower than their calorific value, namely by the amount of the enthalpy of vaporization of the water vapour present.Condensate-resistant heat exchangers are used to exploit the calorific value, i.e. the energy content of the fuel used or of production waste gases containing water vapour. Materials include stainless steel, glass, plastics, etc. Condensing boilers also use the condensation heat (= latent heat) of the water vapor contained in the flue gas (and to a lesser extent other vapors) to provide heat, unlike conventional boilers, which lose around 11 percent latent heat (=condensation heat) when burning gas and around 6 percent when burning EL heating oil.The Kombi Power System ® developed by Gammel Engineering comprises modules for utilizing the calorific value from the combustion of solid, liquid and gaseous fuels.The biomass calculator developed by Gammel Engineering can be used to calculate the wood chip consumption for different types of wood and fuel water contents.
Biomass calculator : http://www.gammel.de/tools/biomasserechner
Solid fuels (at 25 °C)
| Fuel | Calorific value (in MJ/kg) | Calorific value (in MJ/kg) | Calorific value (in kWh/kg) |
|---|---|---|---|
| Forest-fresh wood(1) | * | 6.8 | 1.9 |
| Household waste | * | 9-11 | 2.5-3 |
| Air-dried wood(1) | 19 | 14.4-15.8 | 4-4.4 |
| Paper | * | 15 | 4.2 |
| straw | * | 17.2 | 4.8 [3] |
| Wheat grains | * | 17 | 4.72 |
| Barley grains | * | 18 | 5.0 |
| Wood briquettes | 18.7 | 17.6 | 4.8-5.0 |
| Wood pellets | * | 18 | 4.9 |
| Hemp briquettes | * | 16.7 | 4.7 |
| Peat | 23 | 15 | 4.2 |
| Olive kernels | * | 20 | 5.6 |
| Crude lignite | 10 | 8 | 2.2 |
| Lignite briquettes | 21 | 19.6 | 5.6 |
| Lignite coke | * | 29.9 | 8.3 |
| Brown coal dust | * | 22.0 | 6.1 |
| Stone coal, various types | 29-32.7 | 25-32.7 | 7.5-9 |
| Coal coke | * | 28.7 | 7.97 |
| Carbon dust | * | approx. 21.0 | approx. 5.9 |
| Petroleum coke | * | 31.5 | 8.8 |
| Old tires | * | 32 | 9 |
| Carbon (graphite) | 32.8 | 32.8 | 9.1 |
| Old rubber | * | 35 | 9.7 |
| Paraffin | 49 | 45 | 12.5 |
| Phosphorus | 25.2 | 25.2 | 7 |
| Sulphur | 9.3 | 9.3 | 2.6 |
| Magnesium | 25.2 | 25.2 | 7 |
| Dry stillage | approx. 20.5 | approx. 19 | approx. 5.3 |
(1) Biomass calculator Gammel Engineering http://www.gammel.de/tools/biomasserechner
Liquid fuels (at 25 °C)
| Fuel | Calorific value (in MJ/kg) | Heating value (in MJ/kg) | Heating value (in kWh/kg) | Density (in kg/dm³ (liters)) |
|---|---|---|---|---|
| Petrol | 42.7-44.2 | 40.1-41.8 | 11.1-11.6 | 0.720 - 0.775 |
| Ethanol | 29.7 | 26.8 | 7.4 | 0.7894 |
| Methanol | 22.7 | 19.9 | 5.5 | 0.7869 |
| Diesel, heating oil | 45.4 | 42.6 | 11.8 | 0.820-0.845 |
| Biodiesel | 40 (rapeseed oil di-methyl ester)(2) | 37 | 10.2 | 0.86 - 0.9 |
| Heating oil S | 41.5 | 39.5 | 11.0 | 0.96 - 0.99 |
| Petroleum | * | 42.8 | 11.9 | 0.78 - 1.00 |
| Isopropanol | 33.6 | 30.7 | 8.5 | 0.785 |
| Benzol | 41.8 | 40.1 | 11.1 | 0.879 |
| Bibo(3) | * | 41.8 | 11.6 | 0.796 |
| Paraffin oil | 49 | 45 | 12.5 | 0.81 - 0.89 |
| Old fat(1) | * | 36 | 10 | * |
- (*) currently not known
- (1) Old fat are esters of long-chain fatty acids (usually C18) with glycerine (e.g. rapeseed oil).
- (2) Biodiesel is an ester of long-chain fatty acids (usually C18) with methanol (e.g. rapeseed oil methyl ester).
- (3) Petrol-benzene mixture (gasoline) in the most commonly used mixture "of 6 parts petrol and 4 parts benzene"
Gaseous fuels (at 25 °C)
| Fuel | Calorific value (in MJ/kg) | Heating value (in MJ/kg) | Calorific value (in MJ/m³)(4) | Heating value (in MJ/m³)(4) | Heating value (in kWh/m³)(4) |
|---|---|---|---|---|---|
| Hydrogen | 141,800 | 119,972 | 12,745 | 10,783 | 2,995 |
| Carbon monoxide | 10,103 | 10,103 | 12,633 | 12,633 | 3,509 |
| Gas(1) | 1.5...2.1 | 1.5...2.1 | 2.5...3.4 | 2.5...3.3 | 0,695...0,917 |
| City gas(2) | 18.21 | 16.34 | 19...20 | 17...18 | 4.72...5.00 |
| Natural gas(3) | 36...50 | 32...45 | 35...46 | 31...41 | 8.6...11.4 |
| Methane | 55,498 | 50,013 | 39,819 | 35,883 | 9,968 |
| Ethan | 51,877 | 47,486 | 70,293 | 64,345 | 17,874 |
| Ethylene (ethene) | 50,283 | 47,146 | 63,414 | 59,457 | 16,516 |
| Acetylene (ethine) | 49,912 | 48,222 | 58,473 | 56,493 | 15,693 |
| Propane | 50,345 | 46,354 | 101,242 | 93,215 | 25,893 |
| n-Butane[4] | 49,500 | 45,715 | 134,061 | 123,810 | 34,392 |
| i-Butane[4] | 49,356 | 45,571 | 133,119 | 122,910 | 34,142 |
- Source: Fundamentals of gas technology
- (1) Blast furnace gas consists of (2...4) % hydrogen, (20...25) % carbon monoxide and (70...80) % inert gases (carbon dioxide, nitrogen).
- (2) City gas consists of (19...21) % methane, 51 % hydrogen, (9...18) % carbon monoxide and (10...15) % inert gases.
- (3) Types of natural gas:
- Natural gas "L" consists of approx. 85 % methane, 4 % (ethane, propane, butane, pentane) and 11 % inert gases.
- Natural gas "H" (North Sea) consists of approx. 89 % methane, 8 % (ethane, propane, butane, pentane) and 3 % inert gases.
- Natural gas "H" (CIS countries) consists of approx. 98 % methane, 1 % (ethane, propane, butane, pentane) and 1 % inert gases.
- (4) Volume-related information refers to the normal volume under normal conditions (0 °C and 101325 Pa)
Conversion factors for heating value to calorific value and vice versa according to German EnEV[5]
| Fuel | Heating value → calorific value | Calorific value → Heating value |
|---|---|---|
| Heating oil | 1.06 | 0.943 |
| Natural gas | 1.11 | 0.901 |
| Liquefied natural gas | 1.09 | 0.917 |
Sources :
Wikipedia http://de.wikipedia.org/wiki/Heizwert
Wikipedia http://de.wikipedia.org/wiki/Brennwert
Wikipedia http://de.wikipedia.org/wiki/Brennwertkessel
Gammel Engineering http://www.gammel.de/tools/biomasserechner