The packaged ice industry has an interesting history dating back to cutting ice from glaciers and lakes and storing it in caves for later use. Today we use different methods, but still provide virtually the same product: frozen water. We all do it the same way—apply refrigeration to water to make our product. Even though refrigeration techniques have changed, refrigeration still provides virtually the same product—cold. We make something cold by removing enough heat to make water cold enough to freeze. Without that we cannot make packaged ice or display it for sale.
A brief history of refrigeration for perspective is as follows:
The refrigerator coil was invented during the 11th century by a Persian chemist and physicist named Ibn Sina (980-1037), also known as Avicenna. The coil was used primarily for distillation and not for food storage, but opened the door to refrigeration technology. Not much was done with this technology for seven hundred years until 1748 when William Cullen at the University of Glasgow demonstrated the first artificial refrigeration system, but he never pursued its development. Then in 1805, Oliver Evans developed vapor-compression refrigeration. His theory was to cool by removing heat from the interior of a box by recycling vaporized refrigerant. This vapor moved through the compressor and condenser and was restored to liquid, only to cycle through the system once again.
The first ice making equipment used in the food industry was for transporting frozen meat. Invented and patented in England by Scottish-Australian James Harrison in 1857. His concept of cooling by compression and expansion was made more efficient by a French engineer Ferdinand Carré in 1859 when he substituted ammonia as the refrigerant, which is still widely used. Carré is best known as the inventor of refrigeration equipment used to produce ice.
We continue to use these time tested refrigeration principals in our daily business activities today, but are faced with growing concerns about efficiency and environmental impacts. Our use of electricity is a major expense to make ice and preserve it in cold rooms before delivery. Our refrigeration equipment is much more efficient than even just a few years ago. Even as we have perfected the process and equipment in use, there are other concerns such as the environmental issues related to the use of chlorofluorocarbons (CFC) and hydrofluorocarbons (HFC) and their deleterious effect on the ozone layer. Now is the time for applying new and less destructive technologies to the refrigeration needs of today.
Research is taking place in the EU, USA, Canada, Japan, and China today to develop a commercially viable refrigeration technology known as magneto-caloric cooling. We often hear about disruptive forces in our industries today and magneto-caloric cooling has the potential of being the disrupter for refrigeration in the very near future. The process was discovered in the 1800’s, but has never been commercialized. Now the race is on. There are several prototype machines currently being tested and improved upon. As of this year, there are two commercially available products using magnet-caloric cooling. BASF, Haier and the Astronautics Corporation of America displayed a wine cooler at the Consumer Electronics Show in 2015 and Cooltech of France displayed a medical refrigerator at the MEDICA show this past November. General Electric Appliances, Division of Haier, is developing a home refrigerator at a competitive price point that is expected to be on the market by 2020. This is just the tip of the iceberg (pun intended).
So how is a magnet used to make ice? The magneto-caloric cooling takes place when certain solid materials heat up when placed in a magnetic field and cool down when they are removed from the field. Thermodynamics is way more complicated than I understand, but in simplified language the second law of thermodynamics states that heat always flows from a material at a high temperature to a material at a low temperature. Think of what we use today for refrigeration. The refrigerant, ammonia, Freon, or whatever is in the coil is compressed and then allowed to expand. When it expands heat is removed to a cooler material such as air and expelled. The principle of magneto-caloric cooling is similar. When certain materials are placed in a magnetic field, they heat up, just like when the gas is compressed in your current freezer. When the materials are removed, they cool down, just as when the gas expands. So all we really need is a strong magnet, the right material, and a heat sink to absorb the heat. Seems pretty straight forward, so why are we not using this refrigeration technology today to make our ice and keep our cold rooms cold?
First, we need that magnet. Magnet technology is progressing quickly as more uses are being found. The fast growth of electric cars has been one catalyst for development another is cell phones and other electronic gadgets. In the search for stronger permanent magnets, a number of alloys such as Aluminum-Nickel-Cobalt-Iron were used. Then magnet technology took a giant step in the 1970’s and 80’s when rare-earth elements were incorporated into these magnet alloys. By adding rare-earth elements such as those in the lanthanide family such as lanthanum, samarium, neodymium, yttrium, and several others, permanent magnets became–in some cases–twice as strong as non-rare-earth alloy magnets. Possibly the strongest is a samarium-cobalt magnet.
Rare earths along with metals like lithium and cobalt are seeing soaring demand from a growing electric vehicle market. As recently as 20 February 2018, at a briefing in Tokyo, Toyota announced that it will use the rare earths lanthanum and cerium, which cost only about 5% of the cost of neodymium that is being used in the magnets it now uses. This is one more example of how the cost of this technology is approaching a level to be used in the mass market.
Other actions by companies such as Apple, one of the largest users of cobalt for its batteries, announced during the same week that it will be buying cobalt directly from miners. Apple plans to use long term contracts for thousands of tons of cobalt per year in order to ensure an adequate supply of the material at a reasonable price for its battery needs. The electric car industry is having a ripple effect on demand and price for materials needed to build magnets. This will only put more pressure on the industry to find more ways to offset the cost of these needed materials.
Now that we are finding ways to build affordable and strong permanent magnets that also can operate in the temperature ranges found in our factories without having to acclimatize them. The second component needed to make use of the magneto-caloric effect is the material that will heat when placed in a magnetic field and cool when the magnetic field is removed. Most metals with do this to some degree, but what is needed is a material that demonstrates a significant hot-cold variance. Such a material is said to possess a high magneto-caloric effect (MCE). One element that has shown to work well is gadolinium. When gadolinium and some of its alloys are placed in a strong magnetic field, it quickly heats up. Then, when the magnetic field is removed, it quickly cools down. Another element praseodymium, demonstrates an even stronger effect when alloyed with nickel.
So now we have found two of the three major components needed for an efficient magneto-caloric ice maker. The third is a convenient, safe, and affordable coolant. This is the easiest issue to solve. At the operating environments of our ice factories, it has been determined that water mixed with little ethanol is optimum to be used as the coolant.
These three components can be constructed so that there is a cold side and a hot side, just as in current compressor designed freezers of today. If we hold the high magneto-caloric effect (MCE) material stationary and position the strong permanent magnet so that it moves over the MCE in such a manner so that half the time the MCE is in the magnetic field and half the time it is not in the magnetic field, we find rapid heating then cooling of the MCE. Think of a split wheel made up of the magnet. As the split or half wheel spins around the MCE, the magnetic field is applied to the MCE then removed repetitively. The coolant or heat sink serves to absorb the heat generated when the MCE is in the magnetic field and disposes of it.
This provides the same cold side/hot side as found in a heat pump. The now cold coolant is deployed to the space to be cooled and the heat can be harmlessly dispersed into the air. The amount of electricity needed is now limited to spinning the magnet and pumping the coolant not the greater amount needed to run a compressor to compress the refrigerant. In testing prototypes the electrical savings have been at least 20% and as much as 35% less electricity required for the same cooling capacity when compared to compression designed refrigeration.
Imagine a further future development to use the discarded heat to generate much of the electricity needed to run the magnetic cooling equipment. If you generate enough heat, then you can do what power plants do and use the heat to generate steam, and use the steam to spin a turbine. The turbine can drive a generator and produce electricity. Now the only electricity needed is the amount to offset the friction from the moving parts. That smaller amount of electricity needed could be generated by solar panels and eliminate the need to pay for any electricity for ice production or cooling your cold rooms. This next step might be just a little optimistic, but the future holds many surprises and this might just be one.
Several studies indicate that other benefits also are gained:
1. The environmental friendly technology will remove the need for chlorofluorocarbons (CFC) and hydrofluorocarbons (HFC) that are used in many compression-expansion cooling systems today. The heat transfer coolant to be used in the magneto-caloric cooling systems is water mixed with little ethanol which is environmental friendly and has no ozone depletion effects;
2. The sound and vibration levels in your production facility will be minimized due to the lack of a conventional noisy compressor;
3. Without the need for compressing and decompression a vapor means that the high pressure tubing will not fail and leak gases.
4. The overall cost savings will also come from reduced operational costs, as well as lower maintenance costs.
This all sounds too good to be true, but enough smart people are working on this today and making great strides. Maybe tomorrow the “Ice You Can Trust” made by EPIA ice producers will be produced by magneto-caloric cooling equipment built by and supplied by EPIA equipment providers.
Take look at some of these websites and studies for a better understanding of magneto-caloric cooling and the progress being made today.
By Stan Williams
Managing Director EPIA
http://iowapublicradio.org/post/ames-lab-turns-70-concerns-about-budget-cuts#stream/0 (46 minute public radio discussion, last ½ is magneto-caloric cooling)