Coolant is that type of substance that is used for reducing or regulating the system’s temperature that comes in gas or liquid form. The best coolants you can get is something that have low viscosity, low-cost, chemically inert, non toxic, has high thermal capacity and not promoting or causing corrosion of the cooling system. Some of its applications require the coolant to be electrical insulator as well.
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. The term is covering cutting fluids at the same time. 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.
Air is a very common form of coolant in the market. 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. Because thermal conductivity is higher in comparison to other gases, it is expected to have low density and high specific heat density allowing it to have low viscosity which many rotary machines are taking advantage of due to its vulnerability to windage loss. The hydrogen cooled turbo generators are at the moment most widely used electrical generator in big power plants.
The inert gases are being used as coolants for gas cooled nuclear reactors. Helium basically has low tendency to absorb neutrons and for that, the odds of it becoming radioactive is less. In reality, AGR reactors and Magnox are mixed with carbon dioxide. Sulfur hexafluoride on the other hand is being used for cooling and insulating high voltage power systems similar to switches, transformers, circuit breakers and so on. The steam however could be used where there’s high specific heat capacity that’s required in gaseous form.
A very common type of coolant is water. Its low cost as well as high heat capacity has made it ideal for heat transfer medium. Most of the time, technicians are combining it with additives like antifreeze as well as corrosion inhibitors. The antifreeze is a solution made from suitable organic chemical oftentimes diethylene glycol, propylene glycol or ethylene glycol in water. A similar coolant is betain but with an exception that it’s manufactured using pure plant juice. Pure de-ionized water is used for cooling electrical equipment due to its low electrical conductivity.