The conductive materials heat are those that allow heat to be transferred efficiently from one (or a liquid) high surface temperature and a lower temperature.
Heat conducting materials are used in different engineering applications. Among the most important applications are the construction of cooling equipment, heat dissipation equipment and in general any equipment that requires heat exchange in its processes.
Heat conduction in a material
Those materials that are not good conductors of heat are known as insulators. Among the most used insulating materials are cork and wood.
It is common that materials that conduct heat well are also good conductors of electricity. Some examples of good conductive materials for heat and electricity are aluminum, copper, and silver, among others.
Different materials and their respective heat conduction properties can be found in chemistry manuals that summarize the experimental conduction results performed on these materials.
Heat conduction
Conduction is the transfer of heat that occurs between two layers of the same material or between surfaces in contact of two materials that do not exchange matter.
In this case, the heat transfer in the materials occurs thanks to the molecular collisions that occur between the layers or surfaces.
Molecular shocks allow the exchange of internal and kinetic energy between the atoms of the material.
Thus, the layer or surface with atoms of higher internal and kinetic energy transfers the energy to the layers or surfaces of lower energy, thus increasing their temperature.
Different materials have different molecular structures which causes that not all materials have the same ability to conduct heat.
Thermal conductivity
To express the ability of a material or fluid to conduct heat, the physical property "thermal conductivity" is used, which is usually represented by the letter k.
Thermal conductivity is a property that must be found experimentally. Experimental estimates of thermal conductivity for solid materials are relatively straightforward, but the process is complex for solids and gases.
Thermal conductivity for materials and fluids is reported for a quantity of material with a flow area of 1 square foot, a thickness of 1 foot, for one hour at a temperature difference of 1 ° K.
Heat conductive materials
Although in theory all materials can transfer heat, some have better conduction than others.
In nature there are materials such as copper or aluminum that are good conductors of heat, however materials science, nanotechnology and engineering have allowed the creation of novel materials with good conduction properties.
While a heat-conducting material such as copper, found in nature, has a thermal conductivity of 401 W / K m, carbon nanotubes manufactured with thermal conductivities close to 6600 W / K m have been reported.
Thermal conductivity values for various materials can be seen in the following table:
References
- Berber S. Kwon Y. Tomanek D. Unusualy High Thermal Conductivity of Carbon Nanotubes. Physical Reviews Letters. 2000; 84: 4613
- Chen Q. et al. An alternative criterion in heat transfer optimization. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 2011; 467 (2128): 1012-1028.
- Cortes L. et al. 2010. Thermal conductivity of materials. Metrology Symposium.
- Kaufman WC Bothe D. Meyer SD Thermal Insulating Capabilities of Qutdoor Clothing Materials. Science. 1982; 215 (4533): 690–691.
- Kern D. 1965. Heat Transfer Processes. McGraw hill.
- Merabia S. et al. Heat transfer from nanoparticles: a corresponding state analysis. Proceedings of the National Academy of Sciences of the United States of America. 2009; 106 (36): 15113-15118.
- Salunkhe PB Jaya Krishna D. Investigations on latent heat storage materials for solar water and space heating applications. Journal of Energy Storage. 2017; 12: 243-260.