Wood and Combustion Heat Values
Combustion heat values for Pine, Elm, Hickory and many more species
Sponsored Links
The type of wood burned, whether hardwood or softwood, is important for the heat value and the energy efficiency.
Hardwoods have less resin and burn slower and longer. Softwoods burn quickly. In addition to the type of wood, the seasoned length of the wood influence on the fuel efficiency. Seasoning the wood refers to the allowed drying time before burning.
Moisture reduces the woods fuel value and wood need to be dried at least 4 to 6 months before used.
The table below can be used to indicate density and heat value of some common wood species.
| Wood Species | Density
of Dry Wood (lb/ft3) |
Weight of Dry Cord
(lb) |
Heat Value of
Cord
(Green Wood) (millions Btu) |
Recoverable Heat Value of Cord
(Dry Wood) (millions Btu) |
Units needed to produce 1 Million Btu's |
| Apple | 48.7 | 4,100 | 26.5 | 18.55 | 0.054 |
| Aspen | 27 | 2,290 | 14.7 | 10.29 | 0.097 |
| Balsam Fir | 26.3 | 2,236 | 14.3 | 10.01 | 0.10 |
| Basswood | 24.8 | 2,108 | 13.5 | 9.45 | 0.106 |
| Beech | 44.2 | 3,757 | 24 | 16.8 | 0.060 |
| Black Ash | 35.2 | 2,992 | 19.1 | 13.37 | 0.075 |
| Black Spruce | 29.2 | 2,482 | 15.9 | 11.13 | 0.090 |
| Box elder | 32.9 | 2,797 | 17.9 | 12.53 | 0.080 |
| Cherry | 36.7 | 3,121 | 20 | 14 | 0.071 |
| Cottonwood | 24.8 | 2,108 | 13.5 | 9.45 | 0.106 |
| East Hop hornbeam | 50.2 | 4,267 | 27.3 | 19.11 | 0.052 |
| Elm | 35.9 | 3,052 | 19.5 | 13.65 | 0.073 |
| Hackberry | 38.2 | 3,247 | 20.8 | 14.56 | 0.069 |
| Hemlock | 29.2 | 2,482 | 15.9 | 11.13 | 0.090 |
| Hickory | 50.9 | 4,327 | 27.7 | 19.39 | 0.052 |
| Jack Pine | 31.4 | 2,669 | 17.1 | 11.97 | 0.084 |
| Norway Pine | 31.4 | 2,669 | 17.1 | 11.97 | 0.084 |
| Paper Birch | 37.4 | 3,179 | 20.3 | 14.21 | 0.070 |
| Ponderosa Pine | 28 | 2,380 | 15.2 | 10.64 | 0.094 |
| Red Oak | 44.2 | 3,757 | 24 | 16.8 | 0.060 |
| Red Maple | 34.4 | 2,924 | 18.7 | 13.09 | 0.076 |
| Sugar Maple | 44.2 | 3,757 | 24 | 16.8 | 0.060 |
| Tamarack | 38.2 | 3,247 | 20.8 | 14.56 | 0.069 |
| Yellow Birch | 43.4 | 3,689 | 23.6 | 16.52 | 0.061 |
| White Ash | 43.4 | 3,689 | 23.6 | 16.52 | 0.061 |
| White Oak | 47.2 | 4,012 | 25.7 | 17.99 | 0.056 |
| White Pine | 26.3 | 2,236 | 14.3 | 10.01 | 0.100 |
Note that in the table above 1 cord = 85 ft3 is used between to convert between the "Density" and "Weight of Cord" column. Be aware that the densities used for the wood species may vary significantly. The densities used above is for natural dried wood where the average moisture is approximately 20%.
Heat values of Cords with dry wood can be estimated by adding the green wood cords values with approximately 10%.
Recoverable heat values are calculated with a stove efficiency of approximately 65%.
The Combustion Process of Burning Wood
- At first wood heats up to approximately 212 oF evaporating the moisture in it. There is no heating from the wood at this point.
- Then the wood solids starts to break down converting the fuel gases (near 575 oF).
- From 575 oF to 1100 oF the main energy is released when the fuel vapors containing 40% to 60% of the heat burn.
- After the fuel gases have burned off and the moisture is evaporated, only charcoal remains burning at temperatures higher than 1100o F.
- T(oC) = 5/9[T(oF) - 32]
- 1 m (meter) = 3.2808 ft
- 1 lb = 0.4536 kg
- 1 kWh = 3.6x106 J = 3.671x105 kpm = 859.9 kcal = 2.656x106 ft lbf = 3.412x103 Btu
Sponsored Links
Sponsored Links
SketchUp Engineering ToolBox - Online 3D modeling!
SketchUp Engineering ToolBox - enabled for use with the amazing, fun and free Google SketchUp.
Search the ToolBox
© The Engineering ToolBox 2005
8 5 9
