Conduction in Porous Media Examples of Conduction in Porous Media

The flow of fluid in porous media plays an important role in temperature distribution and heat transfer rate. The term transpiration cooling is used to describe heat removal associated with fluid flow through porous media.
The idea is to provide intimate contact between the coolant and the material to be cooled. Thus heat transfer in porous media is a volumetric process rather than surface action.
Fig. 5.1 illustrates several examples of conduction in porous media. In Fig. 5.1a, a porous ring is placed at the throat of a rocket nozzle to protect it from high temperature damage. Air or helium is injected through the porous ring to provide an efficient cooling mechanism. Fig. 5.1b shows a porous heat shield designed to protect a space vehicle during atmospheric entry.
Cooling of porous turbine blades is shown in Fig. 5.1c . Transpiration cooling has been proposed as an efficient method for protecting microelectronic components. Fig. 5.1d represents an electronic device with a microchannel sink. Coolant flow through the channels provides effective thermal protection. Fig. 5.1e shows a porous fireman’s suit for use in a hot environment. Other examples include heat transfer in blood-perfused tissue and geothermal applications.

Reference: Heat Conduction