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. As a matter of fact, few applications for such need it to be good electrical insulator too.
While coolant is typically referred to HVAC and automotive applications, the industrial coolant is much more of a technical as it’s found in heat transfer fluid frequently used for low as well as high temperature for the manufacturing applications. The term is covering cutting fluids at the same time. Coolants may stay on its phase, gaseous or liquid or, it may undergo a transition with latent heat adding to 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. For the high performance gaseous coolant, hydrogen is what being used most of the time. 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. The helium has low tendency of absorbing neutrons and becoming radioactive. Carbon dioxide is actually used to be mixed with AGR reactors and Magnox. On the other hand, sulfur hexafluoride is used to cool and insulate some high voltage power systems like 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. Antifreeze solution is made out of suitable organic chemicals oftentimes diethylene glycol, propylene glycol or ethylene glycol in water. Betain however is made using pure plant juice but is likely similar with water coolants. Pure de-ionized water is used for cooling electrical equipment due to its low electrical conductivity.