How to cool an object without consuming energy

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This summer has been very hot. One of the hottest on record , and will probably continue to be so. I think we're getting to a point where air conditioning is not just a nice-to-have, but a necessity. There are several ways to cool things down, but the most common method is to use a compressor and refrigerant . However, these traditional air conditioning units are difficult (and expensive) to repair, and they consume quite a bit of electricity. In 2022, 10% of the energy consumed in the United States will be dedicated to cooling the air. That's a lot.

All things emit light
We have to think of alternative ways to reduce the heat. There is an Phone Number List other way to lower the temperature of an object, and it doesn't even require energy or fuel. It's called radiative cooling . Using the right materials, you can make an object radiate more energy than it absorbs, lowering its temperature a few degrees. It seems too good to be true, but it works, thanks to some very interesting ideas in physics.

Everything emits light, and that means everything can transfer thermal energy. It may sound strange, but let's start by thinking about light sources. There are several ways to make an object emit light, but the simplest method is to heat it very much. This is what happens with traditional incandescent bulbs: An electric current passes through a filament inside the bulb and heats it so much that it lights up. That temperature is about 3,600 degrees Fahrenheit (1,982 degrees Celsius). It's simple, and that's why this type of focus has existed for more than 100 years.

But what about things that aren't very hot, like a potato, your favorite shoes, or a doorknob? Yes, they also produce a type of light.

Remember that light is an electromagnetic wave , and all these waves travel at the speed of light (3 x 108 m/s) but with different wavelengths. If the length of this electromagnetic wave is between 400 and 700 nanometers, then we call it visible light, and it is detectable with human eyes. That potato (at room temperature) produces electromagnetic waves with maximum intensity at 9.8 micrometers. We call this region of the electromagnetic spectrum infrared light. It cannot be detected with the eyes, but we can produce an image with an infrared camera.



Here is an example from my dog. Because it is slightly warmer than its surroundings, it produces slightly different wavelengths of light. This means that, in an infrared image, it does not blend into the background.

dog under thermal chamber
My dog's temperature. RHETT ALLAIN
How heat is transmitted
Objects can interact thermally with others in three different ways. The most common method is through heat conduction . This occurs when two objects of different temperatures are in contact and thermal energy is transferred from the hotter object to the colder object , such as when you hold a cold soda can in your hand. The can gets hot and the hand gets cold.