Volumetric heat capacity

Volumetric heat capacity (VHC) describes the ability of a given volume of a substance to store internal energy while undergoing a given temperature change, but without undergoing a phase change. It is different from specific heat capacity in that the VHC depends on the volume of the material, while the specific heat is based on the mass of the material. If given a specific heat value of a substance, one can convert it to the VHC by multiplying the specific heat by the density of the substance.

Dulong and Petit predicted in 1818 that ρcp would be constant for all solids (the Dulong-Petit law). In fact, the quantity varies from about 1.2 to 4.5 MJ/m³K. For fluids it is in the range 1.3 to 1.9, and for gases it is a constant 1.0 kJ/m³K.

The volumetric heat capacity is defined as having SI units of J/(m³·K). It can also be described in Imperial units of BTU/(ft³·F°).

For gases it is useful to distinguish between volumetric heat capacity at constant volume and at constant pressure. This distinction has the same meaning as for specific heat capacity.