Specific heat

n. The amount of heat energy required to raise a unit mass of a substance one degree in temperature.

 

  • Discussion

 

Commonly, specific heat is specified by mass; for example, water has a mass-specific heat capacity of approximately 4.184 joules per gram per degree Kelvin. Volume-specific and molar-specific heat capacities are also used.  Specific heat is an intensive quantity, meaning it is a property of the material itself and not the size or shape of the sample. Its value is affected by the microscopic structure of the material.

 

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The heat capacity of wood depends on the temperature and moisture content of the wood but is practically independent of density or species (Simpson and TenWolde 1999). Heat capacity of dry wood ranges from 1.34 kJ g-1K-1 to 2.01 kJ g-1K-1. The heat capacity of wood that contains water is greater than that of dry wood. Below fiber saturation, it is the sum of the heat capacity of the dry wood and that of water and an additional adjustment factor that accounts for the additional energy in the woodwater bond. The moisture above fiber saturation contributes to specific heat according to the simple rule of mixtures.

 

  • Units

     

    Preferred units of measure for mass-specific heat capacity are kJ g-1K-1.

     

  • References

    • Simpson, W.; TenWolde, A. 1999. Physical properties and moisture relations of wood. In: Wood Handbook: Wood as an Engineering Material. Gen. Tech. Rep. FPL-GTR-113. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory; chapter 3.

     

  • Notes

    • Author 

      Jan van Wagtendonk, Research Forester

      USGS Western Ecological Research Center