OK, you have got your rubber band (hopefully). Take it (*80*) stretch it with your arms, (*80*) preserve it stretched. Now touch the stretched rubber band to your lip (which is very delicate to temperature adjustments). You ought to be capable to really feel the rubber band is hotter than room temperature. Don’t let the rubber band chill out, simply preserve it stretched for slightly while (30 seconds at least). It ought to cool off again right down to room temperature. The subsequent half is the perfect. Finally let that rubber band return to its regular size. Touch it again to your lip (*80*) you possibly can really feel the rubber band is now chilly.
So, here is what occurred. Stretching the rubber band makes it heat up. If you simply let it return again to its authentic size straight away, nothing attention-grabbing occurs. However, by letting the stretched rubber band cool right down to room temperature, it nonetheless decreases in temperature when it returns to its relaxed state—however now it finally ends up colder than room temperature.
This is precisely what a fridge does—except not with rubber bands. Instead it makes use of some kind of liquid gasoline referred to as a refrigerant (there are various completely different chemical compounds you would use right here). You might begin with the refrigerant as a gasoline (*80*) compress it till it turns into a liquid. This compression makes the refrigerant heat up. The subsequent step is to let the compressed refrigerant cool off on the surface of the fridge. Now you possibly can put the refrigerant contained in the fridge (*80*) let it increase again right into a gasoline, (*80*) it cools off—a lot colder than room temperature. That’s how you retain your meals chilly.
But what’s completely different in regards to the –80 diploma freezer for vaccine storage? It seems that it is just about unattainable to get the within temperature of the freezer right down to –80°C with your regular refrigerant. Instead, you want TWO units of refrigerants. It’s sort of like a freezer inside of a freezer. The outer freezer is just about just like the one in your kitchen. The inside freezer makes use of a distinct refrigerant (perhaps isopropyl alcohol) in order that when it is compressed, it may cool off inside of the conventional freezer. But having two compressors is what makes these more costly. Oh, do you need to see an image?
This is the freezer in the biochemistry lab at Southeastern Louisiana University. Now you understand what it seems to be like.
I informed you there was one thing you may be capable to find that was at –80°C, (*80*) it is dry ice—stable carbon dioxide. To make dry ice, you begin with carbon dioxide gasoline. This carbon dioxide gasoline is then cooled (*80*) compressed into liquid carbon dioxide. Then, when the liquid carbon dioxide is eliminated from strain, it turns right into a gasoline once more. But this section transition additionally decreases the temperature (*80*) will get it chilly sufficient to freeze at –80°C to change into a stable.