Coolant is a kind of substance that is either in gas or liquid form that’s being used to regulate or reduce temperature of the system. 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. This term covers cutting fluids too. As for the coolants, it can actually stay on its phase, gaseous or liquid and at times, it undergoes a transition with latent heat which then adds the cooling efficiency. When the latter is utilized for achieving below ambient temperature, it’s automatically called 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. The thermal conductivity is a lot higher compared to all other gases, it has low density and high specific heat density and as a result, low viscosity which is actually a benefit for rotary machines that are vulnerable to windage losses. Currently, many big power plants are using hydrogen cooled turbo generators in their electrical generator.
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. 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. 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. It becomes ideal for heat transfer medium given the fact that it has high heat capacity plus, it is cost effective. 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. 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.