Magnetic Refrigeration FTW!

Jan 7, 2002
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Magnetic refrigeration technology could provide a 'green' alternative to traditional energy-guzzling gas-compression fridges and air conditioners. They would require 20-30% less energy to run than the best systems currently available, and would not rely on ozone-depleting chemicals or greenhouse gases. Refrigeration and air conditioning units make a major contribution to the planet's energy consumption - in the USA in the summer months they account for approximately 50% of the country's energy use.

A magnetic refrigeration system works by applying a magnetic field to a magnetic material - some of the most promising being metallic alloys - causing it to heat up. This excess heat is removed from the system by water, cooling the material back down to its original temperature. When the magnetic field is removed the material cools down even further, and it is this cooling property that researchers hope to harness for a wide variety of cooling applications.

The technology, based on research funded in the UK by the Engineering and Physical Sciences Research Council (EPSRC), has proved possible in the lab but researchers are still looking for improved materials that provide highly efficient cooling at normal room temperatures, so that the technology can be rolled out from the lab to people's homes and businesses.

They need a material that exhibits dramatic heating and cooling when a magnetic field is applied and removed, which can operate in normal everyday conditions, and which does not lose efficiency when the cooling cycle is repeated time after time.

The new study published today shows that the pattern of crystals inside different alloys - otherwise known as their microstructure - has a direct effect on how well they could perform at the heart of a magnetic fridge. The Imperial College London team behind the new findings say this could, in the future, help them to custom-design the best material for the job.



Professor Lesley Cohen, one of the authors of the paper, explains that by using unique probes designed at Imperial, her team, led by Dr James Moore, was able to analyse what happens to different materials on a microscopic level when they are magnetised and de-magnetised. This enabled the team to pinpoint what makes some materials better candidates for a magnetic fridge system than others.

Professor Cohen, from Imperial's Department of Phsyics, said: "We found that the structure of crystals in different metals directly affects how dramatically they heat up and cool down when a magnetic field is applied and removed. This is an exciting discovery because it means we may one day be able to tailor-make a material from the 'bottom up', starting with the microstructure, so it ticks all the boxes required to run a magnetic fridge. This is vitally important because finding a low-energy alternative to the fridges and air conditioning systems in our homes and work places is vital for cutting our carbon emissions and tackling climate change."

This new research follows on from another study published by the same Imperial group in Physical Review B last month, in which they used similar probing techniques to precisely measure the temperature changes that occur when different materials are removed from a magnetic field, and to analyse the different ways they occur.

The lead scientist Kelly Morrison found that at the molecular level two different temperature change processes, known as first- and second-order changes, happen simultaneously in each material. The team think that the extent to which each of these two processes feature in a material also affects its cooling capabilities.

Professor Cohen says this means that whilst the majority of research to perfect magnetic refrigeration worldwide has tended to involve analysing and testing large samples of materials, the key to finding a suitable material for everyday applications may lie in the smaller detail:

"Our research illustrates the importance of understanding the microstructure of these materials and how they respond to magnetic fields on a microscopic level," she concluded.


http://www.physorg.com/news161606698.html
 

allisolm

Elite Member
Administrator
Jan 2, 2001
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#2
They need a material that exhibits dramatic heating and cooling when a magnetic field is applied and removed, which can operate in normal everyday conditions, and which does not lose efficiency when the cooling cycle is repeated time after time.

Do they have any idea whether such a material even exists?

If it doesn't then we are left with: "we may one day be able to tailor-make a material from the 'bottom up', starting with the microstructure, so it ticks all the boxes required to run a magnetic fridge" which seems pretty much like a lot of other "we may one day be able to..." ideas.
 
Apr 18, 2001
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I don't think we'll beat the vapour-compression design for efficiency (equipment and energy costs) any time in my lifetime.
 

iGas

Diamond Member
Feb 7, 2009
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#4

I hope the technology realize soon for the mass market.

A magnetic refrigeration system capable of using the powerful magnetic field of a superconducting magnet to reduce temperatures from room temperature (about 20°C) to about 0°C was first developed in FY2000. Subsequently in FY2003, a system was successfully developed that could reduce the temperature to -1°C by rotating a magnet even with the weak magnetic field of a permanent magnet.

The recently developed magnetic refrigeration system has the following features.

World's highest refrigerating capacity

Refrigerating performance of 540 W achieved with optimal permanent magnet positioning, improved heat exchanger structure and reduced heat infiltration. (This is a nearly ten-fold improvement of refrigerating capacity over the 60 W system developed in FY2003.)
World's highest operating coefficient of performance

Operating coefficient of performance (COP)** of 1.8 achieved (compared to 0.1 with system developed in FY2003)

**Refrigerating capacity divided by energy consumption. The higher the value, the greater the energy savings.
<a target=_blank class=ftalternatingbarlinklarge href="http://www.chuden.co.jp/english/corporate/press2006/1107_1.html">Development of Room Temperature Magnetic Refrigeration System
- World leading performance a big step forward in achieving practical systems -</a>

NIST`s First Magnetic Refrigerator: Quieter, More Energy Efficient

Magnetic refrigeration

 

frostedflakes

Diamond Member
Mar 1, 2005
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#5
Interesting, I hadn't heard about this before. I skimmed the Wiki page and it doesn't sounds like commercialization is that far away.
 
Dec 9, 2001
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#6
When will they make a cpu cooler based on this?
 

skull

Golden Member
Jun 5, 2000
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#7
Thats pretty cool. I've always wondered if theres a way to harness the energy from all the heat in regular systems. Since all the energy used comes out as heat. If you could find a refrigerant that gets hot enough on the high side, use it to boil water and turn a small turbine. Even if its 25% percent efficient, it would make it close to 30% since you don't need the outside fan any more.
 

Eli

Super Moderator | Elite Member
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Oct 9, 1999
50,430
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#8
Interesting.

I don't really get it though. So if you subject a special material to a magnetic field, it heats up. You can then harvest the heat.

When you pull the magnetic field away, the item cools to below ambient? How? Where does the energy go? Is it just radiated away?

:confused:
 
Jan 4, 2001
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#9
Originally posted by: Eli
Interesting.

I don't really get it though. So if you subject a special material to a magnetic field, it heats up. You can then harvest the heat.

When you pull the magnetic field away, the item cools to below ambient? How? Where does the energy go? Is it just radiated away?

:confused:
I'm wondering that too.
 

Eli

Super Moderator | Elite Member
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Oct 9, 1999
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#10
Originally posted by: Jeff7
Originally posted by: Eli
Interesting.

I don't really get it though. So if you subject a special material to a magnetic field, it heats up. You can then harvest the heat.

When you pull the magnetic field away, the item cools to below ambient? How? Where does the energy go? Is it just radiated away?

:confused:
I'm wondering that too.
I wonder if its somehow "pulled" away with the collapsing magnetic field? It would probably just go into heating whatever is creating the magnetic field then. I don't get it.

moar technical article plz, kthx.

Collapsing magnetic fields also tend to induce current in things around them. Hopefully these devices are EMF shielded to the max. ;)
 

frostedflakes

Diamond Member
Mar 1, 2005
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#11
The Wikipedia article describes the cooling cycle, although it's still a bit ambiguous to me as well. In my head it just doesn't seem as intuitive as the traditional refrigeration cycle.

edit: I would probably be able to make sense of this if I had paid more attention in thermodynamics. :p
 
Jan 4, 2001
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#12
Originally posted by: Eli
I wonder if its somehow "pulled" away with the collapsing magnetic field? It would probably just go into heating whatever is creating the magnetic field then. I don't get it.

moar technical article plz, kthx.

Collapsing magnetic fields also tend to induce current in things around them. Hopefully these devices are EMF shielded to the max. ;)
I am aware of conduction and radiation as ways of removing heat from something. (Yes, there's also convection, but it's really just conduction of energy to moving particles in a fluid. ;))

I've not heard of anything concerning magnetic removal of heat...though that sort of thing would likely be beyond the scope of my Heat Transfer course, just as we never talked about using lasers to cool something down to form a Bose-Einstein Condensate.

 

puffff

Platinum Member
Jun 25, 2004
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#14
Originally posted by: allisolm
They need a material that exhibits dramatic heating and cooling when a magnetic field is applied and removed, which can operate in normal everyday conditions, and which does not lose efficiency when the cooling cycle is repeated time after time.

Do they have any idea whether such a material even exists?

If it doesn't then we are left with: "we may one day be able to tailor-make a material from the 'bottom up', starting with the microstructure, so it ticks all the boxes required to run a magnetic fridge" which seems pretty much like a lot of other "we may one day be able to..." ideas.
I interpreted this as they have materials that cool, but not enough for refrigeration.
 
Feb 22, 2007
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#15
I like the old tech of gas powered refrigerators. If more people had homes set up for gas I really think they would be a great alternative.
 
Feb 22, 2007
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#16
Originally posted by: Eli
Interesting.

I don't really get it though. So if you subject a special material to a magnetic field, it heats up. You can then harvest the heat.

When you pull the magnetic field away, the item cools to below ambient? How? Where does the energy go? Is it just radiated away?

:confused:
I'm wondering how they intend to cool the water they are using in the first part of the process.

This excess heat is removed from the system by water, cooling the material back down to its original temperature.
 
Aug 12, 2001
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#17
Originally posted by: Modelworks
Originally posted by: Eli
Interesting.

I don't really get it though. So if you subject a special material to a magnetic field, it heats up. You can then harvest the heat.

When you pull the magnetic field away, the item cools to below ambient? How? Where does the energy go? Is it just radiated away?

:confused:
I'm wondering how they intend to cool the water they are using in the first part of the process.

This excess heat is removed from the system by water, cooling the material back down to its original temperature.
through some sort of radiator I imagine, just like how ordinary refregirators dissipate heat.
 

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