Slashdot Mirror
Inventor of Low Tech Fridge Wins Award
juju2112 writes "Mohammed Bah Abba of Nigeria won a Rolex award for his pot-in-pot invention. Here's how it works. You take a smaller pot and put it inside a larger pot. Fill the space in between them with wet sand, and cover the top with a wet cloth. When the water evaporates, it pulls the heat out with it, making the inside cold. It's a natural, cheap, easy-to-make refrigerator."
Grab a clean sock, soak in water, wring out, cover teh can of beer and leave on the window sill.. LOL
For some reason, I read "pot-in-pot" as more of a smuggler's invention. Ingenious! I'll hide the _REAL_ pot inside this _FAKE_ pot, so they'll never find it!
~i = an imaginary being~
Give a man a rolex, and he's more or less late for a lifetime. Give a man a stick, and he's on time at least once a day.
--
make install -not war
i'd sure like to know how often you have to change the wet sand, in order to get 2 weeks worth of refrigeration?
...
anyone got any napkin-science calculations that can give us a ballpark of whats needed? i'm sure this is a simple physics equation, only i'm certainly not qualified to work out the formula
; -- the corruption of government starts with its secrets. a truly free people keep no secrets. --
This same man (and invention) won an invention of the year award from time (as seen here) in 2001. I guess it's interesting that he also won this award, but why is Rolex handing out awards years after the fact? Maybe I'm just used to the break neck pace of computer advancement, but this seems a little.. late.
Unfortunately such methods have been used in ancient Egypt 4000 years ago already.
Prior art anyone ?
I heard this guy needs someone to transfer the award money for him.
nope - there is something like 4500 years of prior art on this one - bedouin tribes have been using this for ever. I saw this used 10 years ago on holiday in Egypt. So Rolex grabs the first Nigerian that has seen something cool while on holiday and actually implemented it at home, and gives him a friggin "award" for his "invention".
People who think they know everything are a great annoyance to those of us who do.
..but maybe the difference is in the execution or something? To me, it's less important that someone might have done this before than the fact that doing it now might change peoples life to the better.
Shouldn't that be the focus of inventing new ways for doing things by the way? To improve peoples life?
Everything in the world is controlled by a small, evil group to which, unfortunately, no one you know belongs.
Time Magazine invention of the year for 2001
In other news: Man from Nigeria sells Rolex award, buys fridge.
I'm sure some of us geek's will be confused by this "sand" thing they're using in between the pots. This "sand" they talk about is actually just our friend silicon. Just thought I'd throw that out there to avoid some confusion.
But, cut the guy a break. The cool thing here is that he's done it with readily available local materials which is pretty much one of the key features for a real engineer. To paraphrase the old saw:
Anyone can make you an evaporative cooler for $100; this guy's done it for $1.
patent 454,845,474,734
A liquid, excreted from the skin when hot, whose evaporation helps to maintain an organism within a certain temperature range as well as serving to eliminate certain waste materials from the body.
This process may be, but is not necessecarily, augmented by a seperate device composed of a number of curved blades, fitted to a central hub and rotated at high speeds by an electric motor in order to create artificial air currents. some form of material support apparatus keeps the device elevated above the ground, either by providing a stand or attaching to the ceiling of the room, or by mounting the device inside some form of automotive vehicle. Also, a guard device may be used to keep sundry items from coming in contact with the blades.
___
It's the end of my comment as I know it and I feel fine.
Using water to avoid food freezing used to be very common in Norway (and doubtless in other countries with similar climates) before the advent of electricity.
Put a few buckets of water in your food storage room, and as long as the water is not frozen, the food in the room will not freeze either. Just before the water freezes, replace the buckets with liquid water. Repeat as necessary, and the food will not freeze.
Thank god this only needs water, and they have an infinity supply of that in 3rd world countries, as we all well know.
The article didn't mention the effectiveness of the device. Say, on a hot summer day, RH of 80%, if we keep the pot under the shade, could we achieve 15 degree C. A temperature ideal for beer.
The cooling effect has been scientifically studied. Here is this article describing it (Google-translated from Spanish).
Singularity: a belief in the "God" idea with the "demiurge" relation inverted.
This is New?
.from a Mexican. (This serves as an object lesson to me. Even the experts might well overlook simple and obvious tricks that "every child" knows. Even if that expert is me). The water evaporates from the Tshirt drawing heat out of your body.
.for the enviroment. Much of the mythology surrounding the "magical" abilities of the Australian aborigine come from the same source, their technology being too advanced for a European to understand. It was lost technology to them.
No, not particularly. It's a very old trick to make cold water by putting it in an unglazed clay pot, which is porous, and allowing evaporation of the seepage to draw the heat out. I learned it from Mexican Indians 35 years ago and it was effective enough to make water cold enough to make your teeth hurt even in the tropical rainforest. It works even better in the desert where evaporation happens quicker due to the low humidity.
European bicycle racers have been wrapping their water bottles with a damp cloth covering to keep the water chilled for decades as well.
Until a couple of weeks ago I thought everybody knew you could keep cool by wearing a dampened T-shirt, and then I learned that the Pardy's, those paragons of sea lore and self-sufficiency without electrical power, had only just learned this trick. .
Wrap something damp around a pot, as is done with the water bottle, and the air inside the pot chills, as does anything inside the pot. Wrap a porous outer layer around the damp cloth, such as another pot, and you moderate the evaporation rate.
This "invention" seems to miss a few of the finer points of the device, thus requiring the damp cloth over the two pots. You need to use an unglazed pot for the outer one. Then you can even put a real cover on the thing and it still works. Better. Longer. Some sort of batting works better as a wick than sand, although sand will do and is certainly freely available.
I don't mean to denigrate this man's intellectual accomplishment. If he thought it up on his own from basic principles the intellectual feat is equal to the first man that did it.
But it really does amount to the reinvention of folklore that exists in one place in some other place.
And the people from Rolex think of it as a new invention because they are modern, mechanistic folk who don't know how to go about living without modern power and machines or what people who do not have such devices already know about doing so.
The Zapotec Indians I lived among for some months knew lots of tricks that had been handed down over thousands of years for surviving with nothing but what you could make with your own two hands. I've got a poncho just about eight feet from me right now that was woven by them on a backstrap loom they made themselves, with wool from sheep they had grown themselves, sheared themselves, carded themselves, spun themselves, using weaving techniques their ancestors had invented themselves (even though many people throughout the world had invented the same thing). Living with them for a few months taught me more about how to think about living than any number of survival books and hiking expeditions had ever done.
Many of the things they did appeared as magic to me, because I was just an ignorant Americano and their technology was sufficiently advanced. .
I was in Mexico in the late 60s (that's where I first heard Abbey Road). The Zapotecs are starting to lose it too now as they begin to sell their weaving to touristas so that they may buy Tshirts and blue jeans. Most of them buy neon colored acrylic yarn from the store now instead of using their own lovely wool, because the Americanos really like the bright "native" colors instead of the natural tones of wool.
Well, their lot will certainly improve with more money at their disposal, and I certainly won't begrudge them that. Doctors cost serious money no matter how "self-sufficient" they are, and they coul
And I thought Nigerians were the most honest people on earth!
=Smidge=
Basically, the outer clay pot is porous. The water evaporates and escapes through the pores in the clay. This all happens very quickly because the air is so dry. So assuming that 1 kg of water evaporates each hour, this means about 2kJ of energy, and thus heat, is sucked from the pot. So for you non-metric heads, this means that every gallon of water equals 8,000 BTU. For reference, a typical family refigerator might use 7,700,000 BTU/yr, or 900BTU/hr.
You'd be surprised at the massive amount of energy that a liquid-to-vapor phase change can carry away. In fact, six times more energy is needed to turn one molecule of 100C liquid water to one molecule of 100C vapor water than is needed to heat liquid water from 0 to 100C!
Boiling, which is a similar phenomenon, is the most efficient way to transfer heat known to science.
Sig--
1. My girlfriend
2. You
3. ???
4. Profit!
www.eissq.com/BandP.html Ball and Plate System. Amuse your friends. Crush your enemies.
Evaporative coolers such as units from bonair are excellent in dry, hot climates. They constantly draw in dry hot air from outside, drop it by about 10 degrees C and duct it through your house to escape through open doors and windows.
Where I live at present (Mount Isa, Queensland), just about every house and business has at least a 6000cfm evaporative air conditioner. Humidity can often get below 30%, meaning that they work particularly well. In fact, they can theoretically cool to the dew point, which if you take note of the last 72 hr readings from Mount Isa can pull down to 10 degrees or so when it's dry.
They are of course completely fucking useless for about 3 weeks of the year when it's hot and humid and you get storms in the afternoon at 35 degrees and 90% humidity. You just sweat like a pig then, or retreat to the refrigerative airconditioner you normally keep in reserve in your bedroom.
You are in a twisty maze of processor lines, all alike.
There is a lot of hype here.
Prior art apart, this is more a case of practical application on a scale previously unknown for this device.
The main reason for any award that this "device" would be eligible for is of course its social impact. If a simple arrangement of clay pots can prolong the life of perishable food in areas that don't have our "off the shelf from the supermarket perceptual abundance", it's got my vote. If it can drive more kids to school rather than have them vending out on the streets, it should have your vote too.
You might be well right when you say that this is an old invention. But I would caution against demeriting it simpy on account of that. Once again, clearly, the impact of the invention's application counts just as much as (maybe even more than) the invention itself.
One more example of applied commonplace knowledge -- Freeplay radio. Just how long have we known of windup springs and their potential energy???
This isn't actually very different to the way an electric fridge or air conditioner works. The main difference is that in a fridge, the refrigerant is contained within a closed cycle; in this simple evaporative scheme it is lost to the surrounding air. Since it's only water, few people are likely to be bothered about that. That's why, if you have a CFC fridge and it's still working, there's no point getting rid of it ..... the CFCs are sealed up nice and tight inside it, till you scrap it {there's not much you can actually do to get rid of unwanted CFCs, except leak them into the atmosphere when nobody's looking; which is almost certainly what will happen to the CFCs in your fridge, even if you don't put a chisel through the evaporator in a defrosting accident} and making a new one uses up more energy and resources than keeping an existing one going.
The idea that an evaporating liquid draws heat from its surroundings is nothing new.
Basically, the difference between a liquid and a gas is how much the molecules are vibrating: if the vibration is weak, the molecules' affinity for each other bonds them loosely together so they follow one another around, assuming the shape of a container but occupying a definite volume. If the vibration is stronger than that attractive force, then they just fly apart, occupying the whole of the container and exerting a pressure on it. Heating, of course, makes the molecules vibrate more strongly, which is why liquids turn into gases when heated.
If you try to force more molecules into a space, eventually they will be forced into colliding with one another often enough to form a liquid. This is what goes on in a cigarette lighter: there are just too many molecules to behave as a perfect gas, so some of them are forced together and behave as a liquid.
Pressure, volume and {absolute -- i.e. in Kelvins, 0C = 273.15K} temperature are related by the equation: P * V = n * R * T, where n = number of moles of gas and R is the Ideal Gas Constant. No gas is truly ideal, because the assumption is that the individual molecules have neither mass nor volume; however, the relationship holds reasonably well in real life, only deviating sharply around the point where liquefaction actually occurs.
A fridge or air conditioner has three main parts: the compressor, the condenser and the evaporator. The refrigerant gas is first compressed. Pressure goes up and volume goes down, so temperature also goes up. It is then pumped around some pipes at the back of the fridge {or in the outdoor part of the air conditioner; portable units don't have an outdoor section, so the condenser is cooled by blowing air over it and out of a window through a length of flexi-flue -- uncouple this and you've got yourself a de-humidifier} to allow it to cool down. Once the refrigerant has cooled to ambient temperature and become a liquid again, it is forced out by its own pressure through a tiny hole into a larger space {the evaporator - usually the outer jacket of the icemaking compartment of a fridge, or the coil of pipe in the indoor part of an air conditioner that gets covered with ice crystals}. Now the pressure is not sufficient to keep the refrigerant molecules together, so it becomes a gas again. Pressure goes down, volume goes up, so to satisfy the laws of physics, temperature must go down.
The compressor's intake draws the low-pressure refrigerant out of the evaporator and the whole thing starts again. {In an air con., the whole process has to be stopped every so often to allow the accumulated ice to melt off the surface of the evaporator. Plumbed-in units have a permanent drain, portable ones have a tank which needs emptying periodically. The meltwater is pure enough to be used anywhere demineralised water is required.}
You can also get a terracotta butter cooler which works on this principle: the inside of the tray and dome are salt-glazed, the outsides are unglazed. You soak the whole thing in water, which then evaporates slowly from the outer surface, keeping the butter usefully cold {not rock solid, but not runny either}.
Je fume. Tu fumes. Nous fûmes!
I second the people posting that its around 4000 year old method.
I'm from India and I first I read about it when I was around 10 year old (I'm 23) in a popular social magazine (called 'Dharmyuga', the most popular magazine of its time). It had schematics identical to those offered by this fellow, and yes, they mentioned it to be "very old technique". My dad still has collection of old issues of this mag and I'm sure I can fish out the article mentioning this 'invention'.
Can't these fellows do at least a google query to verify that whatever they're offering money for is indeed an invention ??
Several docs with feedback
- mritunjai
Evaporative cooling has been use in kitchens for millenia, although it is usually used to keep water cool (unglazed pots). For storage of more than a few hours, a cellar, solid stone building, or cave is less hassle. You easily get guaranteed 70F or below long-term storage in most regions of the world, and if you are architecturally clever, you can actually get lower-than average-long-term temperatures without any maintenance or needing to re-fill water into little jugs.
> Sure, someone in a developed country might have come up with something more innovative, but they probably don't need the money as much as this guy would.
Hmm.. my inbox tells me they have milions of dollars just lying around there..
I think the point is not that it isn't useful but that it was already being used. My relatives in South Africa know about this trick. The boy scouts use it there for goodness sake. I've been looking around and apparently the "inventor" never even checked the interior temperature of his device. Also the same article seems to indicate the social impacts reported were not indipendantly verified, but reported by Abba himself....
Here is a link to research being done using a similar approach, but more efficient evaproration (not water), and a vacuum, so it can actually produce 2kg of ice a day. (Not in production yet, due to deterioration of the system after a couple of years, but doesn't sound too far off.)
Love many, trust a few, do harm to none.
I live in New Delhi, India-where summer temperatures of 45C are not uncommon. We have what we call 'desert coolers', which are much better than ACs for cooling. Imagine a large metal box with a big fan on one side and straw mats on the other three-which are wetted by water drawn up from the tank below by a pump. The air sucked in by the fan evaps the water, losing heat in the process, and becoming quite cool. I have a large one at home-and I've observed the room temp drop to 22-23C when its above 40 outside. This stuff consumes about 10-20% of the power consumed by an AC-so it's quite good. (power consumption depends on the wattage of the fan, u can put as powerful a fan as you like). They are also quite cheap to make, and it's almost like a cottage industry here-every summer, local shops stock these coolers in various sizes-huge 8' high ones with industrial grade exhaust fans, to cool large areas, to dinky little 'personal coolers'.
However, during the monsoons, or rainy weather-the humidity renders them useless, as evaporation on the straw mats reduces.
Oh, and clay pots have been used in India too, for generations, for keeping water cool-though not in the way mentioned.
"..One hosts to look them up, one DNS to find them, and in the darkness BIND them."
We used to take a hand's width "slice" of straw from the end of a square bale, make it wet and stick in the window - instant air conditioner. The breeze blowing through it (coming INTO the room - you don't want to cool the OUTSIDE) had the heat "removed" with this same process.
I doubt those people have the straw/grass/etc. to waste on A/C, though.
(:
What is new about this is his effort. He maximized his design for over two years to get the maximum affect (prolonging the life of produce) for the least cost. Then he built two factories to produce them and distributed them to rural villagers for free (using his own money). Imagine the changes it made on a culture where food grown would only last 1-2 days once picked if it could now last a month or more!
m 3.html
The real "invention" here is his efforts toward making a positive change in the villager's lifestyle. Obviously if someone is awarding $100,000 dollars there is more to it. You folks should do some more research before you nock it!! He plans to use the $100,000 to distibute the pots more widely and to increase his education efforts!
Learn before you look like a fool:
http://www.varaprasad.htmlplanet.com/custo
I never ceases to amaze me how modern people assume "primitive" means stupid. And that would just be primitive by our standards of technology. Doesn't say anything about thier level of mathmatics or astronomy. There are plenty of amazing things done in history without the use of electricity or modern metals.
For instance the Romans would move water hundreds of miles without the use of any pumps. Only gravity would be used. There is once site in Spain where the Romans used water to tear down a mountain to mine it. Something we would use explosives and heavy machines to do.
I esp. love the nut jobs who assume that because the people of Egypt didn't have bulldozers and crains they couldn't have built the pyramids. Instead it was built by aliens or people from Atlantis. Which is all poppycock, the Egyptians had a prefectly "primitive" way of doing it, we just forgot what it was.
Primitive is relative, but it doesn't mean stupid.
Supporting World Peace Through Nuclear Pacification