The point I’m talking about in this section is that it is super easy to get things hot – because it is likely to happen anyway. Regardless of what you do, the temperature is likely to rise as your actions tend to transfer energy to other objects.
How to make things colder
But what about colder things? It turns out that this is much more complicated. Here are some of the cooling methods we can use:
Put it next to something cold
OK, that’s easy. When you put your drinks in an ice bucket, there is a thermal interaction between the two. The ice gets warmer and your drinks get colder thanks to the magic of thermodynamics.
Just a problem. To use this method, you have to already something cold. Ice is an excellent choice ̵
Of course you can just buy a bag of ice cream in the shop, but earlier they had to find ways to make winter ice cream all year round. There were ice houses with insulation. But the real secret was getting huge ice cubes. A sufficiently large piece of ice takes a long time to melt. This is old technology. Also in the film FrozenKristoff’s job was to harvest sea ice and store it for the summer.
This is my favorite cooling method. It happens when a liquid gets enough energy to become a gas; If it is water, it becomes water vapor. Since this phase transition requires energy, the remaining water remains with lower energy and thus a colder temperature.
This is exactly what your body does when you sweat. Your skin excretes water and when the moisture evaporates, it cools you down. It’s brilliant. Oh, you don’t like to get sweaty? Yes, that happens when the air is humid. The sweat still evaporates from your skin, but water vapor also condenses from the air on your skin. Mesh-Net: wet shirt.
You can also use evaporative cooling for other objects. In fact, there is an old food storage device called a clay pot cooler. Basically, you put food in a clay pot, and this pot goes in another pot with a layer of sand and water in between. When the water evaporates, it cools the inner pot. Of course, this only works in dry areas where the water can evaporate.
What about fans? Yes, when you sit in front of a fan on a hot day, it feels good and cool. But for the most part, fans don’t really lower the temperature of things, they just move air. This increases the rate of evaporation on your skin. But if your skin isn’t sweaty, it won’t do much for you.
There is a situation where fans can work for non-sweaty objects. The fan in your computer increases the airflow over the hot CPU. This has the effect of increasing the thermal contact between the air and the much warmer processor to bring it closer to room temperature. But it cannot get colder than the ambient air.
Compress and expand
Now you are ready for some more modern cooling methods. What about air conditioning in your house or car? What about your fridge Both things work the same way – by heating up. Yes, you can make things cold by heating them up first.