Dry ice engine 16.03.2015

Researchers have figured out how to power the first colonizers of Mars: the planet has a lot of dry ice that can be used to generate available energy.

You have probably noticed how a drop of water, hitting a hot frying pan, begins to roll on the surface. It would seem that the temperature of the pan is much higher than the boiling point of water, and the drop should immediately evaporate, but it still "lives" for some time. This effect was first described by Johann Leidenfrost in 1756. Why doesn't the drop evaporate instantly? It's all about the steam layer, which is formed at the point of contact between the drop and the hot surface. Part of the drop turns into steam, which lifts the drop above the surface, preventing the remaining liquid from evaporating instantly. As a result, the drop runs around the pan for quite a long time.

The Leidenfrost effect isn't limited to frying pans. For example, if you very quickly dip your finger into a glass of liquid nitrogen and quickly pull it back out, then, oddly enough, the finger will not freeze and fall off, although the temperature of liquid nitrogen is -196 ° C. This is due to the fact that liquid nitrogen begins to boil upon contact with warm skin, on which a protective layer of already gaseous nitrogen forms. And gases cool and heat up much more slowly than liquids, so the finger of a reckless experimenter does not have time to freeze. True, there is still a risk of getting burned, so in no case do not test the Leidenfrost effect on yourself. An even more extreme and much more dangerous trick is to lower a wet hand into a container with liquid metal - the water on the surface of the hand instantly boils and for a fraction of a second forms a protective layer between the skin and the molten metal.

Tricks tricks, but how to get real benefit from this phenomenon? Researchers at Northumbria University in the UK have made a prototype engine that can run on a piece of dry ice. The design is based on the same Leidenfrost effect. We remember that a drop of liquid runs over a hot surface. A piece of dry ice behaves exactly the same way if it is thrown into water. Dry ice is unique in that when it is heated from a solid phase it immediately turns into a gas, bypassing the liquid phase. The whole question is how to direct his energy in a useful direction. Engineers have long developed technology to convert steam energy into mechanical energy: in a gas turbine engine, a jet of steam or gas hits the surface of the turbine blades, which starts to rotate. But in our case, the researchers went the other way.

They made the heated surface in the shape of a disk, with a profile similar to the blades of a turbine. Now, if a drop of water is placed on such a heated surface, then the steam formed at the point of contact will not only support the drop in weight, but will also push it in a certain direction. The drop will run around in a circle until it evaporates. But what happens if a disk of dry ice is placed on such a heated surface? Evaporating carbon dioxide will begin to spin the disk, moreover, the surface geometry will not allow it to move off the axis, gas flows will return the disk to the center. Now, if you fix magnets on a disk of dry ice, and place the entire structure inside a conductive circuit, you will get a real electric generator, in which there are no rubbing parts, and hence friction losses. The authors of the invention posted on the site a video of how it all works.

Okay, the prototype engine works, but where do you get fuel for it? Dry ice does not occur naturally. This is where the researchers swung, no less, for generators for future colonizers of Mars or other planets. Many futurologists are sure that sooner or later humanity will have no choice but to populate the planets closest to us.

Now programs are being seriously discussed and developed to send an expedition to the red planet. The members of the expedition will have to equip their lives there, and one of the main problems will be finding sources of energy. The fact is that on Mars, carbon dioxide is often found in solid form, that is, in the form of dry ice. And it can be used as an energy resource. The uniqueness of the invented engine is in the simplicity of design - there are practically no replaceable parts in it. And when the nearest store is more than 50 million kilometers away, the issue of equipment reliability is one of the first places.