When water misbehaves: Amazing video reveals how super-high temperatures cause droplets to travel UPHILL

• This is because of something known as the 'Leidenfrost Effect'
• The effect causes the water to levitate on the evaporated gas vapour 
• Movement can be changed by adjusting the surface texture and temperature

If you’ve ever spilt water on a hot pan, you’ve seen the Leidenfrost Effect in action.

The skittering and fizzing that takes place happens because the surface is super-hot- about twice as hot as the liquid's boiling point.

This causes the water to levitate on the evaporated gas vapour which acts a barrier that keeps the droplet and the hot surface separated.

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The skittering of water occurs because a surface is about twice as hot as the liquid's boiling point. This causes the water to levitate on the evaporated gas vapour which acts a barrier that keeps the droplet and the hot surface separated


Bath University’s Alex Grounds and Richard Still looked at how droplets travel on different textured surfaces, heated at varying temperatures.

They found that they could change the direction of the droplets’ movement by changing the temperature of the ratcheted surface.

They also found that droplets can be made to climb up a steep incline – the sharper the teeth of the surface, the steeper incline they were able to climb.

Water droplets make their OWN way through a metal maze




And so the Leidenfrost Maze was created.

The maze guides the water droplets in different directions using specially-arranged grooved hotplates.

‘We think the droplets change direction depending on how fast the gas evaporates from the surface of the droplet and how much the droplet is levitating, combined with the effect of the textured surface that allows it to be propelled along and even go uphill,’ said researcher Alex Grounds.

The research could be used to develop more sophisticated methods for controlling small droplets and heat transfer, such as cooling systems without moving parts.




Researchers at Bath University have found that water droplets can be made to climb up a steep incline using the Leidenfrost effect – the sharper the teeth of the surface, the steeper incline they were able to climb



The Leidenfrost Maze guides water droplets in different directions using specially-arranged grooved hotplates


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THE LEIDENFROST EFFECT
When a liquid hits something really hot - about twice as hot as the liquid's boiling point - it never comes directly in contact with its surface.

This is because vapour acts as a barrier that keeps the two separated. The skittering of water you see when it hits a hot pan is the Leidenfrost effect.


By ELLIE ZOLFAGHARIFARD

PUBLISHED: 17:27 GMT, 3 October 2013 | UPDATED: 19:31 GMT, 3 October 2013

Read more: http://www.dailymail.co.uk/sciencetech/article-2442638/Leidenfrost-Effect-makes-high-temperature-water-travel-uphill.html#ixzz2ggoZ1BKn
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Kelvin Temperature Scale: Facts and History

The Kelvin temperature scale was the brainchild of Belfast-born British inventor and scientist William Thomson — also known as Lord Kelvin. It is one of the three best-known scales used to measure temperature, along with Fahrenheit and Celsius.

Like other temperature scales, the freezing and boiling points of water are factors in establishing the scale’s range. There are 100 degrees between the temperate at which water freezes at (273.16 K) and boils (373.16 K).

Each unit on this scale, called a Kelvin rather than a degree, is equal to a degree on the Celsius scale. For this reason, just the K, not the degree symbol, is used when reporting temperatures in Kelvin. There are no negative numbers on the Kelvin scale, as the lowest number is 0 K.

The idea for the Kelvin scale was sparked by a discovery in the 1800s of a relationship between the volume and the temperature of a gas. Scientists theorized that the volume of a gas should become zero at a temperature of minus 273.15 C.

The Kelvin scale compared to Celsius and Fahrenheit.
Credit: Designua | Shutterstock

Absolute zero

In 1848, Kelvin used this as a basis for an absolute temperature scale. He defined "absolute" as the temperature at which molecules would stop moving, or "infinite cold." From absolute zero, he used the same unit as Celsius to determine the increments.

Absolute zero cannot technically be achieved. However, scientists have been able to lower the temperature of matter to just a fraction of a Kelvin above absolute zero through techniques such slowing down particles using lasers.

The Kelvin scale was also influenced by the Carnot engine, a theory that examines the relationship between pressure, work and temperature. It is one of the fundamentals of physics and thermodynamics and is a measure of the efficiency of an engine.

Kelvin was a talented mathemetician, which played a role in some of his other inventions, including a device that led to the success of the telegraph cable and many nautical instruments.

His research into the nature of heat helped him form the second law of thermodynamics, which states that heat will not flow from a colder body to a hotter body. Kelvin's documentation of the law says that some of the heat from a high-temperature energy source will be downgraded to low-quality energy.

Uses of the Kelvin scale

The Kelvin scale is popular in scientific applications because of the lack of negative numbers. This scale is convenient for recording the very low temperatures of liquid helium and liquid nitrogen, for example. The lack of negative numbers also makes it easier to calculate differences between temperatures, such as saying one temperature is three times another temperature.

Another absolute temperature scale, the Rankine temperature scale, is used in some engineering applications.

Kelvin is also used for pinpointing color temperature and is typically used in lighting. In a lighting application, Kelvin temperature represents the color temperature, such as white, blue or bright red, that relates to the physical temperature of an object.

During his research, Kelvin heated a block of carbon, progressing from a dim red light, increasing to a brighter yellow as the temperature increased and ultimately a bright blue-white glow at the highest temperatures. 

Conversion rates

Kelvin to Fahrenheit: Subtract 273.15, multiply by 1.8, then add 32.
Fahrenheit to Kelvin: Subtract 32, multiply by 5, divide by 9, then add 273.15.
Kelvin to Celsius: Add 273
Celsius to Kelvin: Subtract 273

By Kim Ann Zimmermann, LiveScience Contributor | September 27, 2013 12:56am ET

http://www.livescience.com/39994-kelvin.html