Coolant is that type of substance that is used for reducing or regulating the system’s temperature that comes in gas or liquid form. Few of the best coolants that can be used are those that are of high thermal capacity, non toxic, chemically inert, low cost, has low viscosity and neither causing or promoting corrosions to the cooling system. As a matter of fact, few applications for such need it to be good electrical insulator too.
While the phrase coolant is referred often to HVAC and automotive applications, industrial coolant is more of a technical as it’s found in heat transfer fluid that are frequently used in low and high temperature manufacturing applications. At the same time, the term is used to cover cutting fluids. Coolants might be able to stay on its phase, gaseous or liquid or it can even undergo a transition with latent heat that adds to the efficiency of cooling. When the latter is used to attain below ambient temperature, it is called automatically as refrigerant.
One typical type of coolant that is used today is air. There are a couple of ways to which air cooling is used and it’s through passive cooling or also known as convective airflow as well as forced circulation by making use of fans. Hydrogen is used too for high performance gaseous coolant. Thermal conductivity is higher in comparison to other gases because it has low density and high specific heat density and for that, it’s low viscosity that is a big benefit for systems using rotary machines that are susceptible to windage losses. The hydrogen cooled turbo generators are at the moment most widely used electrical generator in big power plants.
As for nuclear reactors that are gas cooled, what is used in this purpose is inert gases. Helium has this low tendency to absorb neutrons and become radioactive. Actually, carbon dioxide is also used for mixing it with AGR reactors and Magnox. In regards to sulfur hexafluoride however, this is utilized to insulate and even cool high voltage power systems; to give you examples, it can be switches, transformers, circuit breakers and so on. Whenever there is a need for high specific heat capacity in gaseous form, then expect that steam is what used.
Water is another common type of coolant. The low cost and high heat capacity it has makes it ideal for heat transfer medium. Usually, it’s used with additives similar to antifreeze as well as corrosion inhibitors. In most cases, diethylene glycol, propylene glycol or ethylene glycol mixed in water is the components of antifreeze. Betaine is of similar coolant with an exception that it’s made from pure plant juice and therefore hard to ecologically dispose or non toxic. Because of the low electrical conductivity of pure de-ionized water, it’s widely used for regulating the temperature on electrical equipment.