cool /kuːl/ ~ comfortably free of Heat
Cold & COOL… Did you know (scientifically speaking) that there is no such thing as Cold? If you describe something as Cold, everyone will know what you mean.
But Cold really only means that something has a small amount of Heat. Heat is a form of energy that is in everything. We call this thermal energy.
The temperature of something relates to the amount of Heat it contains.
Heat can be added or taken away. Taking it away makes something Colder.
For example: Imagine an ice cube in the palm of your hand. The warmth (Heat energy) of your hand is absorbed by the ice. The Heat causes the ice to melt. The cooling effect on your hand is the absorbed Heat.
So… to make something Colder you have to take away Heat from it.
Refrigeration means taking Heat away and putting it somewhere else. So if something is to be refrigerated, it is to have Heat removed from it.
In order to refrigerate something, we must find a way to expose it to something else that is Colder, and nature will take over from there.
This is Heat Transfer. The process of producing Cold is a process of removing Heat.
- Cold = Absence of Heat
- Extracting Heat = Cooling
You can remove heat from something (making it colder) until you get to -273ºC. This is called Absolute Zero. (it is VERY difficult to do, even in a laboratory).
So we’ve learnt a little about Heat Transfer. Now we need to know a little about ‘Change of State’ and the ‘Pressure Temperature Relationship’.
