Thermal inertia

Thermal inertia is a term commonly used to describe the observed delays in a body's temperature response during heat transfers.

The phenomenon exists because of a body's ability to both store and transport heat relative to its environment.

Since the configuration of system components and mix of transport mechanisms (e.g. conduction, convection, radiation, phase change) vary substantially between instances, there is no generally applicable mathematical definition of closed form for thermal inertia.

[1] Bodies with relatively large mass and heat capacity typically exhibit slower temperature responses.

Some authors have identified it as an intensive material property, for example in association with thermal effusivity.

It has also been evaluated as an extensive quantity based upon the measured or simulated spatial-temporal behavior of a system during transient heat transfers.

A time constant is then sometimes appropriately used as a simple parametrization for thermal inertia of a selected component or subsystem.

Nowadays the spatial-temporal behavior of complex systems can be precisely evaluated with detailed numerical simulation.

In some cases a lumped system analysis can estimate a thermal time constant.

[4]: 19–26 Analogies of thermal inertia to the temporal behaviors observed in other disciplines of engineering and physics can sometimes be used with caution.

performs nearly the same role in limiting the surface's initial dynamic "thermal inertia" response: as the rigid body's usual heat transfer coefficient