When you stretch a rubber band and hold it under tension, it warms up a little until it matches the ambient temperature. If you release it suddenly, you'll notice that it cooled down. This might seem a bit strange at first, but the laws of thermodynamics aren't broken or anything like that. If entropy continues doing its thing, why not run an experiment? The Applied Science YouTube channel decided to build a refrigerator prototype based on this temperature difference in rubber bands.
The process is very easy to reproduce: Take a rubber band. Place it on your lips, and stretch. You'll notice the rubber band gains temperature, but if you let it relax, it cools down. What is happening? The reason is always the same: Entropy. In normal situations (or at least, the ones we consider 'normal'), when something is compressed it raises its temperature, and when pressure is released it cools. The difference here is that the molecular structure of the rubber band causes it to have greater entropy in its relaxed state. Therefore, when we stretch it, what we do is impose a certain 'order', and temporarily reduce its entropy. Now... what can be done with this?
Cooling with Rubber Bands
On the Applied Science YouTube channel, they decided to test the "refrigeration capacity" of rubber bands. In other words, they created a device that stretches the rubber bands outside and relaxes them inside, anticipating that the combination of multiple bands acts as a refrigerator. The video uses two impressive pieces of technology: a thermal camera called Therm-App that connects to Android devices, and a "manual CNC cutter" named Shaper, which leaves aside long tables and travel axes. The complete refrigerator model was developed in SolidWorks (yes, it still costs a fortune), and the rest comes down to turning the wheel.
No, the rubber band refrigerator is not going to replace traditional systems, but as a proof of concept it works, since the difference reached about two degrees Celsius in the best case. Perhaps it could be improved with a more airtight design or a different kind of rubber band, however, the video fulfills its goal: demonstrating the effect, and why not, serving as "advertising" for those two excellent tools.
https://old.neoteo.com/fridge0-refrigerador-solar-open-source/
