Showing 24 posts tagged heat
The Leidenfrost Maze, designed and built by Carmen Cheng and Matthew Guy at the University of Bath, demonstrates how Leidenfrost droplets can be self-propelled in a controlled way by the jagged texture of the hot surface.
The basic idea is, when a liquid comes in contact with something really hot—about twice as hot as the liquid’s boiling point, although it changes on certain factors like the size of the drop—the liquid never comes in direct contact with the surface; vapor acts as a barrier that keeps the two separated. When you flick drops of water on to a pan to check the heat, that skittering you see and hear is because of this effect.
Cheng and Guy made the aluminum block maze to inspire and share science with local school kids, though we’re guessing every school around the world would love a physics demonstration kit like this.
There are more excellent physics videos in the archives.
BBC News: How do you turn rubbish into energy? Find out how the largest energy recovery facility in Oslo, Norway processes waste and converts it into approximately half of the city’s energy. The integrated waste management system has been so successful that Oslo has had to import trash from other countries to keep up with energy demands.
Simply burning trash is known for putting toxins into the air, but according to recent reports, Waste-to-Energy (WTE) technologies have made advances in “almost completely eliminating" dangerous emissions. WTE supporters also encourage more recycling and minimization of waste as first steps in the waste management heirarchy pyramid.
Also, there’s a huge claw.
Watch more videos about trash in the archives.
Thanks, John Oxton-King.
From a yard in Kampala, Uganda, Moses explains how to build a solar oven using a tire, some glass, newspaper, silver foil, tape, a black pot, and a few hours.
If you’re cooking outside or don’t have an oven, solar ovens are a great alternative for making a hot meal. Building materials are generally inexpensive and easy to find, and rather than requiring fuel or firewood, solar ovens take advantage of a sustainable resource: the sun. How does it work?
- Concentrating sunlight: A reflective mirror of polished glass, metal or metallised film concentrates light and heat from the sun on a small cooking area, making the energy more concentrated and increasing its heating power.
- Converting light to heat: A black or low reflectivity surface on a food container or the inside of a solar cooker improves the effectiveness of turning light into heat. Light absorption converts the sun’s visible light into heat, substantially improving the effectiveness of the cooker.
- Trapping heat: It is important to reduce convection by isolating the air inside the cooker from the air outside the cooker. A plastic bag or tightly sealed glass cover traps the hot air inside. This makes it possible to reach temperatures on cold and windy days similar to those possible on hot days.
- Greenhouse effect: Glass transmits visible light but blocks infrared thermal radiation from escaping. This amplifies the heat trapping effect.
There are more inventions and sustainable ideas in the archives, including Spain’s first 24/7 Concentrated Solar Thermal Power plant.