Global warming is on the rise (Please don’t drop hate mails Mr. Trump). What does it
have to do with our other Mechanical Second half? Well, a lot.
What is cooling? Cooling is what prevents the engine from over-heating and making you feel like sitting in a barbeque. Cooling is what
prevents the space between your legs to cook up when your super bike is standing in the traffic, although not so efficiently, as they end up being cooked up (#SuperBikeProblems).
So how does cooling take place? There are two types of such cooling processes – Air cooled and Water cooled. As the names suggests, the primary medium for an air-cooled system is the air, whereas for the water-cooled is the universal solvent. Air Cooled systems are used in small capacity engines as they need less cooling. They are used in Mopeds, Scooters and Bikes whose Cubic capacity does not exceed 200 cc.
The specific heat of air (Cv for them engineers) is 1 kJ/kg k at 300 K. Heat passes over the engine, collecting all the heat developed due to bombing, and takes it out to the open atmosphere, as the air around us acts as a sink which in layman terms means you can put as much heat into it as you can without affecting the overall temperature.
This heat exchange takes place via conduction. There are ‘fins‘ all over the heat exchange area of the engine. Fins increase the surface area of contact of air with the engine for efficient heat exchange. The air takes the heat from the metal and increases the overall efficiency of the engine.
Heat transfer from fins
The second type of cooling comes in help for heavy cooling. Water has one of the highest specific heat capacities among normal substances. The term ‘Radiator’ that one often hears is the main part of heat exchange. But you ask, radiator exchanges heat with the help of air.
How the cooling system works
Well that’s not the primary heat exchange. It is the water in the radiator that takes up heat from the engine via jackets within the engine. Jacket is the volume around the cylinders which has water flowing through it. The water takes up heat from the
engine, takes it to the radiator. The radiator has a big mesh within it which increases the area to a very large extent and helps in efficient cooling. Various additives are also used to increase the cooling efficiency like coolant ( ever seen the green-hulk sweat?)
In very crude words, the cooling system is to an automobile what the hanging tongue is to dogs.
Oh! And do Electrics require cooling? More on that later!