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| The '''heat of combustion''' (<math>\Delta H_c^\circ</math>) is the [[energy]] released as [[heat]] when a compound undergoes complete [[combustion]] with [[oxygen]] under [[standard conditions]]. The chemical reaction is typically a [[hydrocarbon]] reacting with oxygen to form [[carbon dioxide]], [[water]] and heat. It may be expressed with the quantities:
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| | |
| * energy/[[mole (unit)|mole]] of fuel ([[kilojoule per mole|kJ/mol]])
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| * energy/mass of fuel
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| * energy/volume of fuel
| |
| | |
| The heat of combustion is conventionally measured with a [[Calorimeter#Bomb calorimeters|bomb calorimeter]]. It may also be calculated as the difference between the [[Standard enthalpy change of formation|heat of formation]] <math>\big( \Delta H_f^\circ \big)</math> of the products and reactants.
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| | |
| == Heating value ==
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| | |
| The '''heating value''' (or '''energy value''' or '''calorific value''') of a [[Chemical substance|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 energy value is a characteristic for each substance.
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| It is measured in units of [[energy]] per unit of the substance, usually [[mass]], such as: kJ/kg, [[kilojoule|kJ]]/[[mole (unit)|mol]], [[calorie|kcal]]/kg, [[British thermal unit|Btu]]/lb. Heating value is commonly determined by use of a [[bomb calorimeter]].
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| | |
| Heating value unit conversions (for more visit [http://www.wolframalpha.com Wolfram Alpha]):
| |
| * kcal/kg = MJ/kg * 238.846
| |
| * Btu/lb = MJ/kg * 429.923
| |
| * Btu/lb = kcals * 1.8
| |
| | |
| The heat of combustion for [[fuel]]s is expressed as the HHV, LHV, or GHV.
| |
| | |
| === Higher heating value ===
| |
| The quantity known as higher heating value ('''HHV''') (or ''gross energy'' or ''upper heating value'' or ''gross calorific value'' ('''GCV''') or ''higher calorific value'' ('''HCV''')) is determined by bringing all the products of combustion back to the original pre-combustion temperature, and in particular condensing any vapor produced. Such measurements often use a standard temperature of 25°C. This is the same as the thermodynamic heat of combustion since the [[enthalpy]] change for the reaction assumes a common temperature of the compounds before and after combustion, in which case the water produced by combustion is liquid.
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| The higher heating value takes into account the [[latent heat of vaporization]] of [[water]] in the combustion products, and is useful in calculating heating values for fuels where [[condensation]] of the reaction products is practical (e.g., in a gas-fired boiler used for space heat). In other words, HHV assumes all the water component is in liquid state at the end of combustion (in product of combustion) and that heat below 150°C can be put to use.
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| | |
| === Lower heating value ===
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| The quantity known as lower heating value ('''LHV''') (''net calorific value'' ('''NCV''') or ''lower calorific value'' ('''LCV''')) is determined by subtracting the [[heat of vaporization]] of the water vapor from the higher heating value. This treats any H<sub>2</sub>O formed as a vapor. The energy required to vaporize the water therefore is not released as heat.
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| | |
| LHV calculations assume that the water component of a combustion process is in vapor state at the end of combustion, as opposed to the [[higher heating value]] (HHV) (a.k.a. ''gross calorific value'' or ''gross CV'') which assumes that all of the water in a combustion process is in a liquid state after a combustion process.
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| | |
| The LHV assumes that the [[latent heat of vaporization]] of [[water]] in the fuel and the reaction products is not recovered. It is useful in comparing fuels where condensation of the combustion products is impractical, or heat at a temperature below 150°C cannot be put to use.
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| | |
| The above is but one definition of lower heating value adopted by the [[American Petroleum Institute]] (API) and uses a reference temperature of 60°F (15.56°C).
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| | |
| Another definition, used by Gas Processors Suppliers Association (GPSA) and originally used by API (data collected for API research project 44), is the [[enthalpy]] of all combustion products minus the enthalpy of the fuel at the reference temperature (API research project 44 used 25°C. GPSA currently uses 60°F), minus the enthalpy of the [[stoichiometric]] [[oxygen]] (O<sub>2</sub>) at the reference temperature, minus the [[heat of vaporization]] of the vapor content of the combustion products.
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| The distinction between the two is that this second definition assumes that the combustion products are all returned to the reference temperature and the heat content from the condensing vapor is considered not to be useful.
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| This is more easily calculated from the higher heating value than when using the preceding definition and will in fact give a slightly different answer.
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| | |
| === Gross heating value ===
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| * '''Gross heating value''' (see '''AR''') accounts for water in the exhaust leaving as vapor, and includes liquid water in the fuel prior to combustion. This value is important for fuels like [[wood]] or [[coal]], which will usually contain some amount of water prior to burning.
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| * Note that GPSA 12th Edition states that the Gross Heating Value of a gas is equivalent to Higher Heating Value. This suggests that there may be different standards in play. The use of the term Gross normally describes a larger value than the Net, which usually describes a smaller value. GPSA is consistent with this, and equates the Gross Heating Value to the higher heating value (for a gas - so probably with no liquid water present), and the Net Heating Value to the lower heating value.
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| | |
| === Measuring heating values ===
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| The higher heating value is experimentally determined in a [[bomb calorimeter]]. The combustion of a [[stoichiometric]] mixture of fuel and oxidizer (e.g., two moles of hydrogen and one mole of oxygen) in a steel container at 25° is initiated by an ignition device and the reactions allowed to complete. When hydrogen and oxygen react during combustion, water vapor is produced. The vessel and its contents are then cooled to the original 25°C and the higher heating value is determined as the heat released between identical initial and final temperatures.
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| When the [[lower heating value]] (LHV) is determined, cooling is stopped at 150°C and the reaction heat is only partially recovered. The limit of 150°C is an arbitrary choice.
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| Note: Higher heating value (HHV) is calculated with the '''product of water being in liquid form''' while lower heating value (LHV) is calculated with the '''product of water being in vapor form'''.
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| === Relation between heating values ===
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| The difference between the two heating values depends on the chemical composition of the fuel. In the case of pure carbon or carbon monoxide, the two heating values are almost identical, the difference being the sensible heat content of carbon dioxide between 150°C and 25°C ([[sensible heat]] exchange causes a change of temperature. In contrast, [[latent heat]] is added or subtracted for [[phase transition]]s at constant temperature. Examples: [[Enthalpy of vaporization|heat of vaporization]] or [[Enthalpy of fusion|heat of fusion]]). For [[hydrogen]] the difference is much more significant as it includes the sensible heat of water vapor between 150°C and 100°C, the latent heat of condensation at 100°C, and the sensible heat of the condensed water between 100°C and 25°C. All in all, the higher heating value of hydrogen is 18.2% above its lower heating value (142 MJ/kg vs. 120 MJ/kg). For [[hydrocarbons]] the difference depends on the hydrogen content of the fuel. For [[gasoline]] and [[Diesel fuel|diesel]] the higher heating value exceeds the lower heating value by about 10% and 7% respectively, and for natural gas about 11%. | |
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| A common method of relating HHV to LHV is:
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| ::: HHV = LHV + h<sub>''v''</sub> x (n<sub>H2O,out</sub>/n<sub>fuel,in</sub>)
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| | |
| :where h<sub>''v''</sub> is the heat of vaporization of water, n<sub>H2O,out</sub> is the moles of water vaporized and n<sub>fuel,in</sub> is the number of moles of fuel combusted.<ref>Air Quality Engineering, CE 218A, W. Nazaroff and R. Harley, University of California Berkeley, 2007</ref>
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| Most applications that burn fuel produce water vapor, which is unused and thus wastes its heat content. In such applications, the lower heating value is generally used to give a 'benchmark' for the process; however, for true energy calculations the higher heating value is correct. This is particularly relevant for [[natural gas]], whose high [[hydrogen]] content produces much water. The gross energy value is relevant for gas burned in [[condensing boiler]]s and [[power plants]] with [[flue-gas condensation]] that condense the water vapor produced by combustion, recovering heat which would otherwise be wasted.
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| === Usage of terms ===
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| For historical reasons, the efficiency of power plants and [[combined heat and power]] plants in Europe may have once been calculated based on the LHV. However, this does not seem to be the case nowadays and most countries are tending to correctly use HHV for true efficiency figures. This is becoming noticeable in modern UK energy publications with the increase of energy awareness and based on the simple fact that it is correct. While in the US, values may have been reported to be generally based on the [[Higher heating value|HHV]], although any initial investigation may reveal that the US is still tending to use LHV in some circumstances, whether technically correct or not. This has the peculiar result that contemporary combined heat and power plants, where [[flue-gas condensation]] is implemented, may report efficiencies exceeding 100%. Using LHV in other energy calculations brings similar errors, especially when pulled (incorrectly) into electrolysis calculations etc.
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| Many engine manufacturers rate their engine fuel consumption by the lower heating values. American consumers should be aware that the corresponding fuel-consumption figure based on the higher heating value will be somewhat higher.
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| The difference between HHV and LHV definitions causes endless confusion when quoters do not bother to state the convention being used.<ref>http://www.claverton-energy.com/the-difference-between-lcv-and-hcv-or-lower-and-higher-heating-value-or-net-and-gross-is-clearly-understood-by-all-energy-engineers-there-is-no-right-or-wrong-definition.html</ref> since there is typically a 10% difference between the two methods for a power plant burning natural gas. For simply benchmarking part of a reaction the LHV may be appropriate, but HHV should be used for overall energy efficiency calculations, if only to avoid confusion, and in any case the value or convention should be clearly stated.
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| === Accounting for moisture ===
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| Both HHV and LHV can be expressed in terms of AR (all moisture counted), MF and MAF (only water from combustion of hydrogen). AR, MF, and MAF are commonly used for indicating the heating values of coal:
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| * '''AR''' (As Received) indicates that the fuel heating value has been measured with all moisture and ash forming minerals present.
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| * '''MF''' (Moisture Free) or '''Dry''' indicates that the fuel heating value has been measured after the fuel has been dried of all inherent moisture but still retaining its ash forming minerals.
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| * '''MAF''' (Moisture and Ash Free) or '''DAF''' (Dry and Ash Free) indicates that the fuel heating value has been measured in the absence of inherent moisture and ash forming minerals.
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| == Heat of combustion tables ==
| |
| | |
| {| class="wikitable sortable" style="text-align: right;" align="left"
| |
| |+Higher (HHV) and Lower (LHV) Heating values<BR>of some common fuels<ref name=NIST>[http://webbook.nist.gov/chemistry NIST Chemistry WebBook]</ref>
| |
| ! Fuel !! HHV [[megajoule|MJ]]/kg !! HHV [[BTU]]/lb !! HHV [[kilojoule|kJ]]/[[mole (unit)|mol]] !! LHV MJ/kg
| |
| |-
| |
| |align=left| [[Hydrogen]]|| 141.80 || 61,000 || 286 || 119.96
| |
| |-
| |
| |align=left| [[Methane]] || 55.50 || 23,900 || 889 || 50.00
| |
| |-
| |
| |align=left| [[Ethane]] || 51.90 || 22,400 || 1,560|| 47.80
| |
| |-
| |
| |align=left| [[Propane]]|| 50.35 || 21,700 || 2,220 || 46.35
| |
| |-
| |
| |align=left| [[Butane]]|| 49.50 || 20,900|| 2,877 || 45.75
| |
| |-
| |
| |align=left| [[Pentane]]|| || || || 45.35
| |
| |-
| |
| |align=left| [[Gasoline]] || 47.30 || 20,400 || || 44.4
| |
| |-
| |
| |align=left| [[Paraffin wax]] || 46.00 || 19,900 || || 41.50
| |
| |-
| |
| |align=left| [[Kerosene]] || 46.20 || 19,862 || || 43.00
| |
| |-
| |
| |align=left| [[Diesel fuel|Diesel]] || 44.80 || 19,300 || || 43.4
| |
| |-
| |
| |align=left| [[Coal]] ([[Anthracite]]) || 32.50 || 14,000|| ||
| |
| |-
| |
| |align=left|[[Coal]] ([[Lignite]])|| 15.00 || 8,000 || ||
| |
| |-
| |
| |align=left|[[Wood]] (MAF)|| 21.7 || 8,700 || ||
| |
| |-
| |
| |align=left|[[Peat]] (damp)|| 6.00 || 2,500 || ||
| |
| |-
| |
| |align=left|[[Peat]] (dry)|| 15.00 || 6,500 || ||
| |
| |}
| |
| | |
| {| class="wikitable sortable" style="text-align: right;" align="right"
| |
| |+Higher heating value<BR>of some less common fuels<ref name=NIST/>
| |
| ! Fuel !! HHV [[megajoule|MJ]]/kg !! [[BTU]]/lb !! [[kilojoule|kJ]]/[[mole (unit)|mol]]
| |
| |-
| |
| |align=left| [[Methanol]] || 22.7 || 9,800 || 726.0
| |
| |-
| |
| |align=left| [[Ethanol]] || 29.7 || 12,800 || 1,300.0
| |
| |-
| |
| |align=left| [[1-Propanol]]|| 33.6 || 14,500 || 2,020.0
| |
| |-
| |
| |align=left| [[Acetylene]]|| 49.9 || 21,500 || 1,300.0
| |
| |-
| |
| |align=left| [[Benzene]] || 41.8 || 18,000 || 3,270.0
| |
| |-
| |
| |align=left| [[Ammonia]] || 22.5 || 9,690 || 382.0
| |
| |-
| |
| |align=left| [[Hydrazine]] || 19.4 || 8,370 || 622.0
| |
| |-
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| |align=left| [[Hexamine]]|| 30.0 || 12,900 || 4,200.0
| |
| |-
| |
| |align=left| [[Carbon]] || 32.8 || 14,100 || 393.5
| |
| |}
| |
| | |
| {{clear}}
| |
| | |
| {| class="wikitable sortable" style="text-align: right;"
| |
| |+Heat of Combustion for some common fuels (higher value){{cn|date=November 2013}}
| |
| |-
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| ! Fuel
| |
| ! [[kilojoule|kJ]]/g
| |
| ! [[kilocalorie|kcal]]/g
| |
| ! [[BTU]]/lb
| |
| |-
| |
| |align=left|[[Hydrogen]]
| |
| | 141.9
| |
| | 33.9
| |
| | 61,000
| |
| |-
| |
| |align=left|[[Gasoline]]
| |
| | 47.0
| |
| | 11.3
| |
| | 20,000
| |
| |-
| |
| |align=left|[[Diesel fuel|Diesel]]
| |
| | 45.0
| |
| | 10.7
| |
| | 19,300
| |
| |-
| |
| |align=left|[[Ethanol]]
| |
| | 29.7
| |
| | 7.1
| |
| | 12,000
| |
| |-
| |
| |align=left|[[Propane]]
| |
| | 49.9
| |
| | 11.9
| |
| | 21,000
| |
| |-
| |
| |align=left|[[Butane]]
| |
| | 49.2
| |
| | 11.8
| |
| | 21,200
| |
| |-
| |
| |align=left|[[Wood]]
| |
| | 15.0
| |
| | 3.6
| |
| | 6,000
| |
| |-
| |
| |align=left|[[Coal]] ([[Lignite]])
| |
| | 15.0
| |
| | 4.4
| |
| | 8,000
| |
| |-
| |
| |align=left|[[Coal]] ([[Anthracite]]){{cn|date=November 2013}}
| |
| | 27.0
| |
| | 7.8
| |
| | 14,000
| |
| |-
| |
| |align=left|[[Natural Gas]]
| |
| | 54.0
| |
| | 13.0
| |
| | 23,000
| |
| |}
| |
| | |
| {{clear}}
| |
| | |
| == Lower heating value for some organic compounds (at 15.4°C){{Citation needed|date=May 2011}} ==
| |
| | |
| {|- class="wikitable"
| |
| ! Fuel
| |
| ! [[megajoule|MJ]]/kg
| |
| ! [[megajoule|MJ]]/[[liter|L]]
| |
| ! [[BTU]]/lb
| |
| ! [[Joule|kJ]]/[[mole (unit)|mol]]
| |
| |-
| |
| ! colspan="5" | Alkanes
| |
| |-
| |
| | [[Methane]]
| |
| | 50.009
| |
| | —
| |
| | 21,504
| |
| | 802.34
| |
| |-
| |
| | [[Ethane]]
| |
| | 47.794
| |
| | —
| |
| | 20,551
| |
| | 1,437.2
| |
| |-
| |
| | [[Propane]]
| |
| | 46.357
| |
| | —
| |
| | 19,934
| |
| | 2,044.2
| |
| |-
| |
| | [[Butane]]
| |
| | 45.752
| |
| | —
| |
| | 19,673
| |
| | 2,659.3
| |
| |-
| |
| | [[Pentane]]
| |
| | 45.357
| |
| | 28.39
| |
| | 21,706
| |
| | 3,272.6
| |
| |-
| |
| | [[Hexane]]
| |
| | 44.752
| |
| | 29.30
| |
| | 19,504
| |
| | 3,856.7
| |
| |-
| |
| | [[Heptane]]
| |
| | 44.566
| |
| | 30.48
| |
| | 19,163
| |
| | 4,465.8
| |
| |-
| |
| | [[Octane]]
| |
| | 44.427
| |
| | —
| |
| | 19,104
| |
| | 5,074.9
| |
| |-
| |
| | [[Nonane]]
| |
| | 44.311
| |
| | 31.82
| |
| | 19,054
| |
| | 5,683.3
| |
| |-
| |
| | [[Decane]]
| |
| | 44.240
| |
| | 33.29
| |
| | 19,023
| |
| | 6,294.5
| |
| |-
| |
| | [[Undecane]]
| |
| | 44.194
| |
| | 32.70
| |
| | 19,003
| |
| | 6,908.0
| |
| |-
| |
| | [[Dodecane]]
| |
| | 44.147
| |
| | 33.11
| |
| | 18,983
| |
| | 7,519.6
| |
| |-
| |
| |-
| |
| ! colspan="5" | Isoparaffins
| |
| |-
| |
| | [[Isobutane]]
| |
| | 45.613
| |
| | —
| |
| | 19,614
| |
| | 2,651.0
| |
| |-
| |
| |-
| |
| | [[Isopentane]]
| |
| | 45.241
| |
| | 27.87
| |
| | 19,454
| |
| | 3,264.1
| |
| |-
| |
| | [[2-Methylpentane]]
| |
| | 44.682
| |
| | 29.18
| |
| | 19,213
| |
| | 6,850.7
| |
| |-
| |
| | [[2,3-Dimethylbutane]]
| |
| | 44.659
| |
| | 29.56
| |
| | 19,203
| |
| | 3,848.7
| |
| |-
| |
| | [[2,3-Dimethylpentane]]
| |
| | 44.496
| |
| | 30.92
| |
| | 19,133
| |
| | 4,458.5
| |
| |-
| |
| | [[2,2,4-Trimethylpentane]]
| |
| | 44.310
| |
| | 30.49
| |
| | 19,053
| |
| | 5,061.5
| |
| |-
| |
| ! colspan="5" | Naphthenes
| |
| |-
| |
| | [[Cyclopentane]]
| |
| | 44.636
| |
| | 33.52
| |
| | 19,193
| |
| | 3,129.0
| |
| |-
| |
| | [[Methylcyclopentane]]
| |
| | 44.636?
| |
| | 33.43?
| |
| | 19,193?
| |
| | 3,756.6?
| |
| |-
| |
| | [[Cyclohexane]]
| |
| | 43.450
| |
| | 33.85
| |
| | 18,684
| |
| | 3,656.8
| |
| |-
| |
| | [[Methylcyclohexane]]
| |
| | 43.380
| |
| | 33.40
| |
| | 18,653
| |
| | 4,259.5
| |
| |-
| |
| ! colspan="5" | Monoolefins
| |
| |-
| |
| | [[Ethylene]]
| |
| | 47.195
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Propylene]]
| |
| | 45.799
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[1-Butene]]
| |
| | 45.334
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[cis-2-Butene]]
| |
| | 45.194
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[trans-2-Butene]]
| |
| | 45.124
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Isobutene]]
| |
| | 45.055
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[1-Pentene]]
| |
| | 45.031
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[2-Methyl-1-pentene]]
| |
| | 44.799
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[1-Hexene]]
| |
| | 44.426
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| ! colspan="5" | Diolefins
| |
| |-
| |
| | [[1,3-Butadiene]]
| |
| | 44.613
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Isoprene]]
| |
| | 44.078
| |
| | -
| |
| | —
| |
| | —
| |
| |-
| |
| ! colspan="5" | Nitrous derivated
| |
| |-
| |
| | [[Nitromethane]]
| |
| | 10.513
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Nitropropane]]
| |
| | 20.693
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| ! colspan="5" | Acetylenes
| |
| |-
| |
| | [[Acetylene]]
| |
| | 48.241
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Methylacetylene]]
| |
| | 46.194
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[1-Butyne]]
| |
| | 45.590
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[1-Pentyne]]
| |
| | 45.217
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| ! colspan="5" | Aromatics
| |
| |-
| |
| | [[Benzene]]
| |
| | 40.170
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Toluene]]
| |
| | 40.589
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[o-Xylene]]
| |
| | 40.961
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[m-Xylene]]
| |
| | 40.961
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[p-Xylene]]
| |
| | 40.798
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Ethylbenzene]]
| |
| | 40.938
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[1,2,4-Trimethylbenzene]]
| |
| | 40.984
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Propylbenzene]]{{dn|date=January 2013}}
| |
| | 41.193
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Cumene]]
| |
| | 41.217
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| ! colspan="5" | Alcohols
| |
| |-
| |
| | [[Methanol]]
| |
| | 19.930
| |
| | 15.78
| |
| | 8,570
| |
| | 638.55
| |
| |-
| |
| | [[Ethanol]]
| |
| | 28.865
| |
| | 22.77
| |
| | 12,412
| |
| | 1,329.8
| |
| |-
| |
| | [[1-Propanol]]
| |
| | 30.680
| |
| | 24.65
| |
| | 13,192
| |
| | 1,843.9
| |
| |-
| |
| | [[Isopropanol]]
| |
| | 30.447
| |
| | 23.93
| |
| | 13,092
| |
| | 1,829.9
| |
| |-
| |
| | [[n-Butanol]]
| |
| | 33.075
| |
| | 26.79
| |
| | 14,222
| |
| | 2,501.6
| |
| |-
| |
| | [[Isobutanol]]
| |
| | 32.959
| |
| | 26.43
| |
| | 14,172
| |
| | 2,442.9
| |
| |-
| |
| | [[Tert-butanol]]
| |
| | 32.587
| |
| | 25.45
| |
| | 14,012
| |
| | 2,415.3
| |
| |-
| |
| | [[1-Pentanol|n-Pentanol]]
| |
| | 34.727
| |
| | 28.28
| |
| | 14,933
| |
| | 3,061.2
| |
| |-
| |
| | [[Isoamyl alcohol]]
| |
| | 31.416?
| |
| | 35.64?
| |
| | 13,509?
| |
| | 2,769.3?
| |
| |-
| |
| ! colspan="5" | Ethers
| |
| |-
| |
| | [[Methoxymethane]]
| |
| | 28.703
| |
| | —
| |
| | 12,342
| |
| | 1,322.3
| |
| |-
| |
| | [[Ethoxyethane]]
| |
| | 33.867
| |
| | 24.16
| |
| | 14,563
| |
| | 2,510.2
| |
| |-
| |
| | [[Propoxypropane]]
| |
| | 36.355
| |
| | 26.76
| |
| | 15,633
| |
| | 3,568.0
| |
| |-
| |
| | [[Butoxybutane]]
| |
| | 37.798
| |
| | 28.88
| |
| | 16,253
| |
| | 4,922.4
| |
| |-
| |
| ! colspan="5" | Aldehydes and ketones
| |
| |-
| |
| | [[Methanal]]
| |
| | 17.259
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Ethanal]]
| |
| | 24.156
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Propionaldehyde]]
| |
| | 28.889
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Butyraldehyde]]
| |
| | 31.610
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Acetone]]
| |
| | 28.548
| |
| | 22.62
| |
| | —
| |
| | —
| |
| |-
| |
| ! colspan="5" | Other species
| |
| |-
| |
| | [[Graphite|Carbon (graphite)]]
| |
| | 32.808
| |
| | —
| |
| | —
| |
| | —
| |
| |-
| |
| | [[Hydrogen]]
| |
| | 120.971
| |
| | —
| |
| | 52,017
| |
| | 244
| |
| |-
| |
| | [[Carbon monoxide]]
| |
| | 10.112
| |
| | —
| |
| | 4,348
| |
| | 283.24
| |
| |-
| |
| | [[Ammonia]]
| |
| | 18.646
| |
| | —
| |
| | 8,018
| |
| | 317.56
| |
| |-
| |
| | [[Sulfur]] (<small>solid</small>)
| |
| | 9.163
| |
| | —
| |
| | 3,940
| |
| | 293.82
| |
| |-
| |
| |}
| |
| | |
| Note that there is no difference between the lower and higher heating values for the combustion of carbon, carbon monoxide and sulfur since no water is formed in combusting those substances.
| |
| BTU/lb values are calculated from MJ/kg (1 MJ/kg = 430 BTU/lb).
| |
| | |
| == Higher heating values of natural gases from various sources ==
| |
| | |
| The International Energy Agency reports the following typical higher heating values:<ref name=KWES>[http://iea.org/dbtw-wpd/Textbase/nppdf/free/2005/key2005.pdf Key World Energy Statistics (2005), page 59]</ref>
| |
| | |
| * [[Algeria]]: 42.00 MJ/m³
| |
| * [[Bangladesh]]: 36.00 MJ/m³
| |
| * [[Canada]]: 38.20 MJ/m³
| |
| * [[Indonesia]]: 40.60 MJ/m³
| |
| * [[Netherlands]]: 33.32 MJ/m³
| |
| * [[Norway]]: 39.88 MJ/m³
| |
| * [[Pakistan]]: 34.90 MJ/m³
| |
| * [[Russia]]: 38.23 MJ/m³
| |
| * [[Saudi Arabia]]: 38.00 MJ/m³
| |
| * [[United Kingdom]]: 39.71 MJ/m³
| |
| * [[United States]]: 38.42 MJ/m³
| |
| * [[Uzbekistan]]: 37.89 MJ/m³
| |
| | |
| The lower heating value of natural gas is normally about 90 percent of its higher heating val.
| |
| | |
| == See also ==
| |
| | |
| * [[Adiabatic flame temperature]]
| |
| * [[Combustion]]
| |
| * [[Energy density]]
| |
| * [[Energy value of coal]]
| |
| * [[Exothermic reaction]]
| |
| * [[Fire]]
| |
| * [[Fuel efficiency#Energy content of fuel]]
| |
| * [[Food energy]]
| |
| * [[Internal energy]]
| |
| * [[Thermal efficiency]]
| |
| * [[Wobbe index]]: heat density
| |
| * [[ISO 15971]]
| |
| *[[Electrical efficiency]]
| |
| *[[Mechanical efficiency]]
| |
| *[[Figure of merit]]
| |
| *[[Relative cost of electricity generated by different sources]]
| |
| *[[Energy conversion efficiency]]
| |
| | |
| == References ==
| |
| | |
| {{Reflist}}
| |
| * "Carburants et moteurs", J-C Guibet, Publication de l'Institut Français du Pétrole, ISBN 2-7108-0704-1
| |
| | |
| == External links ==
| |
| * [http://webbook.nist.gov/chemistry/ NIST Chemistry WebBook]
| |
| * [http://www.wendellhull.com ASTM Standard Testing]
| |
| | |
| {{DEFAULTSORT:Heat Of Combustion}}
| |
| [[Category:Chemical engineering]]
| |
| [[Category:Combustion]]
| |
| [[Category:Fuels]]
| |
| [[Category:Thermodynamics]]
| |
| [[Category:Nuclear physics]]
| |
| [[Category:Thermochemistry]]
| |
| [[Category:Thermodynamic properties]]
| |
| | |
| [[ar:قيمة حرارية]]
| |
| [[ja:燃焼熱]]
| |
| [[sv:Förbränningsvärme]]
| |