Physicists at the University of Amsterdam have come up with a really cool Christmas decoration: a miniature Christmas tree, just 8 centimeters tall, made from ice, without any refrigeration or other freezing technology, and at minimal cost. The secret is evaporative cooling. preprint posted in the physics section of arXiv.
Evaporative cooling is a well-known phenomenon; Mammals use it to regulate body temperature. You can see this in your morning cup of hot coffee: hotter atoms rise to the top of a magnetic trap and “jump out” as steam. It also plays a role (along with shock wave dynamics and various other factors) in formation from “wine tears.“This is a key step in creating Bose-Einstein condensates.
And evaporative cooling is also the main culprit the notorious “stall” this is so often a concern for new barbecue masters looking to make a successful pork butt. As the meat cooks, it sweats, releasing internal moisture that evaporates and cools the meat, effectively neutralizing the heat from the barbecue. That's why more and more professionals wrap meat in foil after the first few hours (usually when the internal temperature reaches 170°C).° F).
Ice printing methods typically rely on cryogenics or refrigerated substrates. According to the authors, this is the first time evaporative cooling principles have been applied to 3D printing. The trick was to place the 3D print inside a vacuum chamber, using an inkjet nozzle as the print head – something they discovered serendipitously when they were trying to get rid of air resistance by spraying water into the vacuum chamber. “The printer's motion control directs the water jet layer by layer, creating geometry on demand,” the authors wrote in a Nature blog post, adding:
