Meaning of thermal conductivity (what is it, concept and definition)

What is Thermal Conductivity:

Thermal conductivity is a physical property of materials or bodies that determines the ability to transport heat by conduction directly and without exchange of matter.

Each material has a specific thermal conductivity that characterizes heat transport, which always flows spontaneously and from highest to lowest temperature. Therefore, heat is transported from one body to another body that is at a lower temperature.

Bodies are made up of atoms and molecules, so when a body is hot, its atoms and molecules move quickly and transport their energy to the other, less hot body. It is a continuous energy transport until the object reaches thermal equilibrium.

Consequently, transporting heat from one matter or body to another also involves an energy exchange, in this case kinetic energy is produced (energy that a body possesses according to its movement).

However, there are bodies or materials whose thermal conductivity is scarce and the inverse property of conductivity is generated, which is thermal resistivity. In other words, the lower the thermal conductivity, the greater the heat insulation, for example, metals have a higher electrical conductivity than gases.

See also the meaning of Conductivity.

Electric conductivity

Electrical conductivity is the ability of bodies or materials to transport electrical energy from one body to another. In contrast, thermal conductivity carries heat.

See also the meaning of Electrical Conductivity.

Transport of thermal energy

Conduction: heat is transported by contact. Metals like aluminum or iron are excellent conductors of heat.

Convection: heat is transmitted by contact with transfer of the same material that emits heat.

Radiation: heat is transmitted through electromagnetic waves, such as heat that reaches Earth through solar waves.

Thermal conductivity measurement unit

In the International System of Units, thermal conductivity is measured as follows: W / (Km) (watts per Kelvin and meter), which is equivalent to J / (sKm) (Joules per second, Kelvin and meter).

Thermal conductivity is represented by the Greek letter λ (lamda). However in the United States it is represented by the letter k.

Thermal conductivity in materials

Thermal conductivity in metals: metals are good conductors of heat, among the most common are aluminum, copper and iron. Some metals are also good conductors, both thermal and electrical.

For example, an aluminum frying pan is placed on the burning stove, when it comes into direct contact with the fire, it quickly heats up and allows cooking of some food.

Thermal conductivity in liquids: liquids are also good conductors of heat, since connective currents are generated between the molecules of water and in this way, cold molecules are mixed with hot ones until they all have the same temperature.

For example, when a cold teaspoon is placed on a hot soup plate, the liquid will heat the cutlery based on its temperature.

Thermal conductivity in adiabatic materials: these are materials whose properties are characterized by being poor thermal conductors. These materials include wool, wood, paper, plastic, fiberglass, and cork.

For example, wood works as a heat insulator when placed on the handle of pans or pots, to avoid burning your hands when holding these hot objects.

Some of these materials are also used in house manufacturing to maintain internal temperatures and prevent them from changing rapidly. In the winter season these insulators keep the internal temperatures of the home stable.