Einstein’s Refrigerator Using No Electricity/No Freon Revived at Oxford

It looks like Einstein did his best not only in quantum physics, but also in classic, immediately-helpful science. Back in the 1930’s, helped by his friend Leo Szilard, he invented a non-electric refrigerator. Scientists from Oxford are struggling to revive his invention today.

Modern refrigerators are working on the principle on contraction and expansion of the freon. We all have freon in our refrigerators. It’s a synthesized gas, causing greenhouse effects worse than CO2. It’s said that the Einstein refrigerator is one of the most important invention of the 20th century, since it stopped the spread of infectious diseases caused by rotten food – worldwide. So there are more and more refrigerators being used, then dumped, and their freon going into the upper layers of the atmosphere, causing greenhouse effects.

Malcolm McCulloch, an electrical engineer from Oxford, whose passions are green technologies, is leading a project to revive Einstein’s refrigerator and other lost-and-found inventions that require no electricity to make our lives better.

Einstein and Szilard’s non-electric refrigerator used only pressurized ammonia, butane and water to keep the things cool. Their invention was used in the early refrigerators, then it was dropped once the technology evolved and more efficient freon compressors have been used since the 1950s.

The main principle behind Einstein’s refrigerator is that the water boils at lower temperatures when the surrounding air pressure is lower. For example, if you go on a mountain, you’ll see the difference between the boiling point from there and the boiling point from your home (or the sea altitude). If you live on a mountain, then you’re lucky – you’ll boil your eggs faster in the morning.

McCulloch describes the device rebuilt by him. At one side is the evaporator, a flask that contains butane gas. “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. That’s what makes it cold”, he says.

But Einstein and Szilard refrigerator was inefficient with that time’s technology, so the producers passed on to using freon gas and compressors. McCulloch, on the other hand, believes that by modifying the design and replacing the gas types he uses, he will be able to obtain 4 times Einstein’s efficiency. Going a little bit further, he wants to insert a solar powered heat pump (to be green) into the non-electric refrigerator. ‘No moving parts is a real benefit because it can carry on going without maintenance. This could have real applications in rural areas,’ he says.

Other researchers, working at Cambridge, got the idea of cooling without adding extra energy by using magnetic fields. “Our fridge works, from a conceptual point of view, in a similar way (to freon fridges) but instead of using a gas we use a magnetic field and a special metal alloy. 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. 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.” said managing director Neil Wilson. We had an article earlier this year reporting that a crew from Denmark was able to do that in practice.

But Einstein/Szillard/McCulloch’s refrigerator is still in a study process, and it is at this point far from being commercialized (as he says). It’s still a promise to keep our eyes on and a very interesting alternative that we never thought would exist! He says “Give us another month and we’ll have it working”.

There are still a lot of things that we take for granted as they are and don’t do a thing to improve them. And if we don’t do that, and invent good things above relatively bad ones, what do we get? Evolution? No. All we get is a sand castle that’s going to fall soon.

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