| Efficient Magnetic Cooling |
| Written by Hank Green | |
| Tuesday, 04 September 2007 | |
 A word of caution, the article that I pulled this story from is titled "Magnetic Refrigerator Needs No Electricity." That headline is a big fat lie...but the technology is still interesting.Indeed, this new cooling technology does use electricity, it just uses a lot less electricity per degree of heat removed from a system. The technology is based on a magnetic heat pump instead of an electric heat pump. The good news is that the magnetic system is completely silent and uses 60% less energy. The bad news is that it's much more expensive to create and can currently only cool a system about 10 degrees cooler than it's surroundings. That's bad news if you want your house to be 70 when it's 90 outside. But the researchers at the Technical Unviersity of Denmark are working on the problem, and say they will have a working (though certainly expensive) prototype in 2010. Via Denmark.dk Comments
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written by Joel , September 05, 2007
The distinction you wanted to make between this technology and what people have in their homes isn't well expressed by magnetic vs. electric. While a type of purely electric heat pump (Peltier effect) is in use in some vehicle refrigerators, the bulk of refrigeration and air condition is accomplished by evaporation.
Unfortunately "evaporative cooling" is usually reserved for the ambient-pressure evaporation of water, even though systems that use anhydrous ammonia or Freon-like chemicals also work by evaporation. Perhaps a better wording would be "a magnetic heat pump instead of a mechanical heat pump". After all, as you've said, both run on electricity.
refrigerators and freezers?
written by kballs , September 06, 2007
Though it's easier to cool a sealed insulated box, you'd need about 60F (33C) drop for a refrigerator (assuming optimal internal temp of 40F with a 100F ambient temp) and a 75F (41C) drop for a freezer (assuming optimal internal temp of 25F with a 100F ambient temp).
It might be tougher with their magnetic evaporator... though it should still be possible because it's still using evaporative technology (same physics) which is still the most efficient way we have at transferring/absorbing heat (peltiers/thermoelectric coolers are still not that efficient though they have very desirable reliability/runtime attributes since they are solid state). Cost-wise, I wonder how the magnetic evaporators compare with the mechanical turbine/water evaporative systems they have now (which are supposed to be more efficient and more environmentally friendly, but more expensive than R-134a compressor systems). | |
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That's a change of about 11degC. The article said they had 'already' cooled a room by 9C, so we can only expect them to do better.
Regardless, assuming the same difference is possible at greater temperatures, a potential drop from 33C (93F) to 24C (77F) is not negligible for air conditioning.