Volumetric Heat Capacity

Dulong and Petit predicted in 1818 that ρc_p 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 0.001 MJ/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° ).

THERMAL INERTIA

''Thermal inertia'' is a term commonly used by Engineers modelling Heat Transfer s when referring to the volumetric heat capacity. For example, ''this material has a high thermal inertia.'' Or, ''thermal inertia plays an important role in this system,'' which means that Dynamic effects are prevalent in a Model , so that a Steady-state calculation will yield inaccurate results.

It is more of an easy language shortcut than a real scientific analogy. In Mechanics , Inertia is what limits the Acceleration of an object. Because of Inertia you can't bring a car from 0 to 100 mph in 0.1 seconds (or rather you can, but the forces involved would be so great that they would likely tear the vehicle apart, as in car crashes). Similarly, in Heat Transfer , a higher value of the volumetric heat capacity means a longer time for the system to reach Steady-state .

CONSTANT VOLUME AND CONSTANT PRESSURE.

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 .

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Volumetric Heat Capacity