Double Dribble

The rest of the world is finally confronting a problem that we have been dealing with for years. "How do you get a teapot not to dribble?"  A team of Fluid Dynamicists  from the University of Lyon have discovered a way to interrupt the hydro-capillary behavior of water that is the cause of the problem. Part of their solution is something that we have all know for years, like building a thinner lip with a sharp edge. But the second part of their solution is pretty cool. Of course it does lead to the common ceramics question. "Is that food safe?"

Here is the article from the M.I.T. Technology Review.

Teapot technology is largely ignored by mainstream media (some say unfairly). But today, scientists in France unveil a technique that should breath hi-tech life into a new generation of bespouted objects. 


The problem with teapots is their annoying habit of dribbling, particularly at low rates of flow. The phenomenon has achieved such notoriety that it has been imaginatively dubbed the "teapot effect". 


Previous studies have shown that dribbling is the result of flow separation where the layer of fluid closest to the boundary becomes detached from it. When that happens, the fluid flows smoothly over the lip. But as the flow rate decreases, the boundary layer re-attaches to the surface causing dribbling.


Previous studies have shown that a number of factors effect this process such as the radius of curvature of the teapot lip, the speed of the flow and the "wettability" of the teapot material. But a full understanding of what's going on has so far eluded scientists.


Now Cyril Duez at the University of Lyon in France and a few amis, have identified the single factor at the heart of the problem and shown how to tackle it. They say that the culprit is a "hydro-capillary" effect that keeps the liquid in contact with the material as it leaves the lip. The previously identified factors all determine the strength of this hydro-cappillary effect.


So how to overcome it? There are two ways say Duez and co. The first is to make the lip as thin as possible. That's why teapots with spouts made from thin metal are less likely to dribble.


The second is to coat the lip with the latest generation of superhydrophobic materials which strongly repel water. Duez and co show how this stops dribbling at a stroke. "Superhydrophobic surfaces fully avoid dripping, and thus beat the "teapot effect"," they say.


(Of course, there are one or two other potential applications in shaping the fluid flow in microfluidic machines but these pale into insignificance compared with the teapot revolution in hand.)


The really exciting news, however, is that in certain materials the hydro-capillary effect can be controlled electronically. That raises the possibility of a teapot design in which dribbling can be turned on and off with the flick of a switch--an object of desire on a par with the iPhone, USB catapaults and personal hovercrafts. (The iPot , perhaps?)


If this doesn't win these guys an IgNobel, I don't know what will.


Thanks to Darren P. for the heads up!


Link

Some like it Hot

Scientists Develop Intelligent Coffee Mug

By Sabine Wygas

Materials to keep drinks cold or hot for longer have been around for quite a while. Now a pair of German scientists has come up with a high-tech mug they claim keeps coffee at the perfect temperature.

The idea came to the researchers at the Christmas market in the Bavarian town of Rosenhiem. "We got upset because the mulled wine" -- Glühwein, in German -- "was always either too hot or too cold," say Klaus Sedlbauer, the head of the Fraunhofer Institute for Building Physics (IBP), and his colleague Herbert Sinnesbichler. "We had to find a solution."

And find a solution they did. The two scientists found it in phase change material (PCM), a wax-like substance used in the construction materials industry that is normally used to ensure comfortable room temperatures in the summer without having to use any energy for air conditioners.

The material can be embedded within plaster boards or placed on walls and ceilings -- where it absorbs and stores warmth, such as that emitted by the sun during the day, and releases it once again after the sun has gone down, thereby creating a pleasant room temperature at all hours. "But," Sedlbauer adds," a lot of winter and ski jackets also contain PCM to keep people warm. Most people probably have some somewhere in their closet."

PCMs also have long-term memory capabilities that make them ideal for storing computer data over extended periods of time without any need for an electrical current. For example, researchers at the Berlin-based Paul Drude Institute for Solid State Electronics (PDI) are looking into exactly why the material has these storage capacities.

A Highly Active Internal Life

The researchers at IBP came up with the idea of using PCM in coffee mugs. If it works in large office spaces and in jackets, why couldn't it also keep a cup of coffee warm? To test their theory, they created the first PCM mug. The high-tech mug is made using a porcelain shell whose hollow interior is filled with a honeycomb structure made of ribbons of highly conductive material, such as aluminum. This honeycomb structure is then filled with PCM. "So now, if you are drinking hot coffee in one of these cups," Sinnesbichler explains, "the drink's heat is directed straight into the still solid PCM. This heat, in term, melts the PCM -- kind of like wax -- and turns it into a liquid."

Once the material has become liquid, it retains thermal energy, but without absorbing any more heat. The temperature at which it becomes liquid depends on the specific type of PCM, each of which has slightly different chemical properties and melting temperature. "Warm drinks -- like coffee or tea -- are best enjoyed at 58 degrees Celsius (136.4 degrees Fahrenheit)," Sedlbauer explains. "In order to reach and maintain this temperature, we fill the mug with a type of PCM that becomes a liquid at exactly 58 degrees Celsius."

The material absorbs the warmth of the mug's content like a sponge, stores it and brings it down to the optimal temperature. And then the PCM helps maintain the content's temperature at this optimal level by slowly releasing the stored heat back into the mug's contents. "Under ideal circumstances," Sedlbauer says, "the optimal temperature can be maintained for 20-30 minutes."

In order to even further insulate the mug and permit less heat to be lost, the outside part of the mug's hollowed-out cavity -- that is, the part farthest from the material whose temperature needs to be maintained -- is lined with a razor-thin layer of either plastic or ceramics. This helps further ensure that the contents of the mug only start cooling down once the PCM has released all of its stored thermal energy and returned to a solid state.

Hot & Cold Double Functionality

But PCMs aren't just about keeping things warm. "Cold drinks or ice can also be well regulated in PCM cups or mugs," Sinnesbichler says. As he explains, beer tastes best at 7 degrees Celsius (44.6 degrees Fahrenheit), and ice is best at -12 degrees Celsius (10.4 degrees Fahrenheit). "So you want to make cups or mugs that have a PCM type that melts at exactly these temperatures," he says. For the consumer, this unfortunately means that you need different types of high-tech mugs for different beverages, depending on whether you want them hot, cold or ice-cold.

Researchers at the Bavarian Center for Applied Energy Research (ZAE Bayern) in Garching think that the fact that PCM is so cheap to produce could make it attractive for numerous additional applications. For example, it could be used to keep perishable foods from spoiling for longer or prevent sensitive machine components from overheating. Another idea involves blanketing the interior walls of museums with the non-flammable material in order to protect paintings from heat damage in case of a fire.

In the meantime, it won't be long before the IBP's new table products arrive in stores. Their steep price tags should easily give them away. "We don't know how expensive they'll be yet," Sedlbauer says. "We are already talking with different companies. If we can find a partner to work together with, the first mugs could already be on sale by the end of the year."

Via: Der Spiegel

She's a, Brick House! (research facility)

Clemson brick center serves as industry’s CSI lab

By John Staed
Wednesday, July 29, 2009

Photo by Sefton Ipock

Jim Frederic, the associate director of the Bishop Ceramic Laboratory, says he installed old kiln burners at the facility so students can see how it operates before they enter the industry.

Photo by Sefton Ipock

Greg Bellotte moves a cart of bricks inside a testing area at the Bishop Ceramic Laboratory.

PENDLETON — If there were a “CSI” for bricks, this would have to be their lab.

It’s the National Brick Research Center in north Anderson County at the Clemson Research Park.

In the popular TV series, investigators leave no stone unturned, pardon the pun, in search of evidence in a crime.

While there’s no crime to solve at the brick center, a lot of stones are turned in search of answers for brick makers, ceramics manufacturers and related industries.

Researchers crush, heat, freeze, drown and squeeze brick material to learn how it is affected.

The result of their work is given back to industry, which uses it to make better bricks, to architects, who use it to design structures, or to government agencies, who need restoration ideas.

The brick center is a component of Clemson University, but is overseen by a board from the Brick Industry Association. The building opened at the research park in 1996. Dues from the association and fees for research support the 12-person operation. Next door is the Tile Council of America, which shares some research and office space with the brick researchers.

Jim Frederic, associate director of the brick center, said its mission is three-fold: research projects for the industry, service work for individual companies, and education, for industry and Clemson materials science and engineering students.

“We hold a lot of seminars for people associated with the brick industry,” he said.

Those could be technical training for brick makers, to inform them of new processes, or with architects, to tell them of changes in the materials, or with other related industries, he said.

Testing may be for durability, strength or water absorption levels of brick material. Or it may be environmental in nature — helping a company make bricks or ceramics more efficiently, thus saving energy, or determining if materials can be dumped under more stringent landfill regulations.

“A lot of waste materials are now used in brick manufacturing,” Frederic said. “We are working with all these plants on questions of what can they use, what causes problems, what are green products.”

The process of making brick has changed, but the fundamentals could be considered similar to that of the ancients: You mix a batch of clay (or like material), add ingredients for strength, color, and more, then bake it in a kiln for a day or a few hours.

That process mostly has become automated and expensive, Frederic said. In the past, bricks were made in small batches in coal-heated kilns, but today a brick maker may run 100,000 bricks a day in a fully automated natural gas-heated kiln that requires only a night watchman to check on it. If a brick maker has to shut down a kiln today, it becomes expensive.

So many will ask the research center to test materials to determine how they can be made, or what changes should be included in a formula. That way, they can run the kilns without shutting them down and incorporate the change into their operations, Frederic said.

While the less-glamorous side of brick and ceramics testing is the main focus, the center has begun working more with government agencies to test materials of older structures, said DenisBrosnan, director.

In his office are Fort Sumter wall materials, which the center is testing to help the National Parks Service decide how to replace eroding brick and mortar. It is one area where the center is attempting to broaden its services — and add revenues, he said.

“Our role is to provide materials analysis to help them come up with an analysis” of the structures’ conditions, he said. “We are trying to do more than testing, but look at what is causing wear and tear on a building.”

The center also has provided public service work, meaning free analysis. It examined materials from an old Pickens church and more recently analyzed brick used from an Anderson church that burned.

Via: Independent Mail

This place sounds a lot like what my research group does up here in Alfred, for the whitewares industry.