Gases
Air is a common form of a coolant. Air cooling uses either convective airflow (passive cooling), or a forced circulation using fans.
Hydrogen is used as a high-performance gaseous coolant. Its thermal conductivity is higher than all other gases, it has high specific heat capacity, low density and therefore low viscosity, which is an advantage for rotary machines susceptible to windage losses. Hydrogen-cooled turbogenerators are currently the most common electrical generators in large power plants.
Inert gases are used as coolants in gas-cooled nuclear reactors. Helium has a low tendency to absorb neutrons and become radioactive. Carbon dioxide is used in Magnox and AGR reactors.
Sulfur hexafluoride is used for cooling and insulating of some high-voltage power systems (circuit breakers, switches, some transformers, etc.).
Steam can be used where high specific heat capacity is required in gaseous form and the corrosive properties of hot water are accounted for.
Read more about this topic: Coolant
Famous quotes containing the word gases:
“The bird is not in its ounces and inches, but in its relations to Nature; and the skin or skeleton you show me, is no more a heron, than a heap of ashes or a bottle of gases into which his body has been reduced, is Dante or Washington.”
—Ralph Waldo Emerson (1803–1882)