A fridge that uses no energy?

[Alan H]

Mmmm...not sure about this...

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Einstein fridge design can help global cooling | Science | The Observer
http://www.guardian.co.uk/science/2008/ ... matechange
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Einstein fridge design can help global cooling
Scientists relaunch a 1930 invention that uses no electricity and would reduce greenhouse gases

* Alok Jha, green technology correspondent
* The Observer,
* Sunday September 21 2008
* Article history

An early invention by Albert Einstein has been rebuilt by scientists at Oxford University who are trying to develop an environmentally friendly refrigerator that runs without electricity.

Modern fridges are notoriously damaging to the environment. They work by compressing and expanding man-made greenhouse gases called freons - far more damaging that carbon dioxide - and are being manufactured in increasing numbers. Sales of fridges around the world are rising as demand increases in developing countries.

Now Malcolm McCulloch, an electrical engineer at Oxford who works on green technologies, is leading a three-year project to develop more robust appliances that can be used in places without electricity.
Einstein refrigerator

His team has completed a prototype of a type of fridge patented in 1930 by Einstein and his colleague, the Hungarian physicist Leo Szilard. It had no moving parts and used only pressurised gases to keep things cold. The design was partly used in the first domestic refrigerators, but the technology was abandoned when more efficient compressors became popular in the 1950s. That meant a switch to using freons.

Einstein and Szilard's idea avoids the need for freons. It uses ammonia, butane and water and takes advantage of the fact that liquids boil at lower temperatures when the air pressure around them is lower. 'If you go to the top of Mount Everest, water boils at a much lower temperature than it does when you're at sea level and that's because the pressure is much lower up there,' said McCulloch.

At one side is the evaporator, a flask that contains butane. 'If you introduce a new vapour above the butane, the liquid boiling temperature decreases and, as it boils off, it takes energy from the surroundings to do so,' says McCulloch. 'That's what makes it cold.'

Pressurised gas fridges based around Einstein's design were replaced by freon-compressor fridges partly because Einstein and Szilard's design was not very efficient. But McCulloch thinks that by tweaking the design and replacing the types of gases used it will be possible to quadruple the efficiency. He also wants to take the idea further. The only energy input needed into the fridge is to heat a pump, and McCulloch has been working on powering this with solar energy.

'No moving parts is a real benefit because it can carry on going without maintenance. This could have real applications in rural areas,' he said.

McCulloch's is not the only technology to improve the environmental credentials of fridges. Engineers working at a Cambridge-based start-up company, Camfridge, are using magnetic fields to cool things. 'Our fridge works, from a conceptual point of view, in a similar way [to gas compressor fridges] but instead of using a gas we use a magnetic field and a special metal alloy,' said managing director Neil Wilson.

'When the magnetic field is next to the alloy, it's like compressing the gas, and when the magnetic field leaves, it's like expanding the gas.' He added: 'This effect can be seen in rubber bands - when you stretch the band it gets hot, and when you let the band contract it gets cold.'

Doug Parr, chief scientist at Greenpeace UK, said creating greener fridges was hugely important. 'If you look at developing countries, if they're aspiring to the lifestyles that we lead, they're going to require more cooling - whether that's air conditioning, food cooling or freezing. Putting in place the technologies that are both low greenhouse-gas refrigerants and low energy use is critical.'

McCulloch's fridge is still in its early stages. 'It's very much a prototype; this is nowhere near commercialised,' he said. 'Give us another month and we'll have it working.'

[Retrieved: Sun Sep 21 2008 13:08:17 GMT+0100 (GMT Daylight Time)]

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[Archipet]

The article describes the invention as a refrigerator that runs without electricity - not without energy! The energy source it requires is external heat to increase the temperature and pressure of the refrigerant(s). Gas-powered fridges work in this way, using a small burner to heat the refrigerant outside the cold chamber. This vapourises when it is discharged into the cooling coils, drawing its latent heat of vapourisation from the metal of the coils which, in turn, draw heat from the contents of the cold chamber.

The article points out that these designs were superseded by compressor-driven refrigeration because they were less efficient.

Modern, electrically powered fridges are around 10 times more energy-efficient than typical models from 15 - 30 years ago. We don't need to wait for fridges designed by Einstein to start saving electricity on cooling - we simply need to replace our old, inefficient appliances with modern ones that are rated A++ for energy efficiency. These could be made still more efficient (for example, using vacuum panel walls) but the manufacturers do not feel any demand for this from their customers.

The cooling needs in the developing world are beset with similar problems to heating and lighting. Energy-efficient systems exist but newly-affluent people in the emerging economies want what we've got. For example, they would rather have AC power from the grid because it's perceived as more useful than DC from a solar panel. You can run an iron with it, not just a couple of lightbulbs and a phone charger. The magical energy solutions for the developing world will be the ones that we in the west are willing to adopt at home. If an Einstein fridge with no plug, just a solar heating panel, becomes the latest must-have in London and New York then it will be welcomed throughout Africa and Asia. That's convergence!

[Alan H]

But it'll need electricity for the light!

Thanks for the explanation.

[Alan C.]

Do you need a light inside your fridge?

[Alan H]

How else do you see the mould?

[Parapraxis]

There is something quite peaceful about going down to the fridge at midnight and being illuminated by that enigmatic glow...mould or no mould!

[Nick]

Being Electric Angel, should you not be declaring an interest?

[Parapraxis]

I'm renewable energy, my wings are solar-powered.

[Alan H]

I'm renewable energy, my wings are solar-powered.

Just remember Icarus!

[Parapraxis]

But I want a tan, and I can't wait for global warming :(

[tubataxidriver]

This is a useful guide to spotting such nonsense.

Checklist%20for%20identifying%20dubious%20technical%20processes%20and%20products.pdf

(57.79 KiB) Downloaded 104 times

[Alan H]

Excellent!