This is a most excellent place for technology news and articles.
Elastocaloric coolers are not new. There are even some versions that you can buy right now, they usually for niche industrial use and have their own set of problems, namely that they're not remotely as efficient as vapor compression so it costs more and moves less heat.
The breakthrough here was discovering a different alloy that allows sub-zero temperatures. It doesn't change the efficiency which is the primary barrier to adoption.
So multiple, nickel-titanium alloy tubes, are stretched and released within the refrigerator, causing a temperature change in the alloy, the heat of which (pulled from the interior) transferred to the calcium chloride fluid, being pumped around through the tubes; to be transferred to the outdoor climate, by use of an exterior heat exchanger. Something along those lines?
But past cooling devices have not had enough cooling power for commercial use. The HKUST team developed a device that uses a new type of solid refrigerant, a nickel-titanium alloy with a higher nickel ratio. They also use calcium chloride as the working fluid that transfers heat away for cooling. Their design connects multiple alloy tubes together for a cascading effect that amplifies cooling.
In outdoor tests, the desktop device cools a surface down from 24°C to -12°C, and froze water in two hours. Sun Qingping, the mechanical and aerospace engineering professor who led the work, said in a press release that the researchers plan to increase the system’s efficiency and make it more cost-effectiveness by using advanced shape memory alloy materials and trying different system designs.
Cool.
Er, so to speak.
Finally, someone else in this thread that sees the potential.
Jesus Christ, whoever wrote this "article" has no idea what they're talking about. The researchers achieved sub-zero temperatures with a solid refrigerant, which is impressive. It has however absolutely nothing to do with climate change, because the heat still has to go somewhere. And the point that gas refrigerants are horrible greenhouse gases is not generally true anymore. Most new systems use gases as refrigerants that have equal or less impact on the atmosphere than co2 if they're released into the atmosphere. And that only happens if the loop is damaged, under normal operation it should stay sealed.
Under normal operation, in a perfect system it will stay sealed. Problems come at end of life and in real world use. Seals aren't perfect, gas escapes slowly. Some seals are bad, a blast chiller at my work needs regassing every other year. People dump old fridges and freezers on the street and they get damaged.
It all gets out eventually.
Yes, but the amount of gas in an AC system is insignifcant compared to the CO2 generated just making the AC system in the first place. Hell, delivering it probably generated significantly more pollution. Not saying we shouldn't strive to make it better, but it's not as actively harmful as it was 30+ years ago.
What heat are you referring to? Refrigeration simply moves heat using electricity to pump refrigerant through a cycle of physical changes, aka heat pumps.
Im sure that this doesn't violate the laws of thermodynamics, but the headline makes it sound like this magics away the heat without using electricity or putting the heat anywhere.
Ye canna change the laws of physics, Captin.
Also Titanium is a bitch to extract if I recall correctly, hence the price. Still, options are good.
Ye canna change the laws of physics, Captin.
No, but you can write a bullshit article that has very little bearing on reality.
Goes quadruple for its title.
Agreed. But you can cool without heating the planet. It doesn't violate the laws of thermodynamics because it just uses a larger system - I.e. nocturnal radiative cooling.
No it said it does it without refrigerant.
The headline reads "A new cooling technology freezes food without warming the climate". It doesnt mention the lack of (gaseous) refrigerent.
The thing about machines that make them bad for the environment in general is the fact that they use up energy, which is nowadays still mostly created in a process that also releases massive amounts of CO2.
Its unlikely that the environmental impact of the gaseous refrigerent is as big as the impact of the CO2 that is created to run the fridge over its lifetime. It makes sense then to assume this fridge doesnt use power, since right now thats the only way it could cool without heating up the planet.
Im not saying this tech isnt interesting, but the headline is total BS
Old school refrigerants were absolutely horrendous ghg even modern ones are pretty bad with R134 being 1430x worse of a ghg than CO2
If we can reduce that, that’s good! And metals like titanium are recyclable so yes initially extracting them is bad but the full lifecycle isn’t as terrible
It doesn't use refrigerant, which is full of HFCs, HCFCs and CFCs.
Coefficient of performance (i.e. energy efficiency) at decent delta-T is always the most important factor and rarely mentioned.
Modern cooling equipment generally has the largest environmental impact from energy consumption, not manufacturing or refrigerant leakage.
Especially with ultra-low-GWP propane or butane refrigerant, though that's not usually used in large-scale systems.
First law of thermodynamics...
This made me wonder how much heat/emissions are generated creating liquid nitrogen. 🤔
You just compress the gas to make it liquid, right?
How do you separate it?
Fractional distillation of liquid air I believe (like separating petrol and diesel).
I'm sure it's more complex than I'm making it out to be, but each gas in the air has its own freezing/melting boiling/condensation/sublimation points, so I'd imagine you could just kind of take advantage of that
Basically just cool it down to x temperature at y pressure, and all of the carbon dioxide should be solid, the oxygen a liquid and the nitrogen still a gas, and they've all sort of separated themselves out. Fish out the dry ice, siphon off the oxygen, and you're left with nitrogen.
Might need to do a couple more rounds of that on each of those to account for other gases in the mix depending on how pure you need it to be, but in theory I imagine it could be that simple (again in practice I'm sure there's probably a lot of details I'm missing)
There are filters that you just need a little compression to get close to pure nitrogen out of, then a lot of cooling to liquify it.
Generally it’s made by first filtering out other gasses (there are materials that will pass nitrogen but block oxygen), and then you just get it super cold with a cryocompressor (uses helium as a refrigerant) to liquify it.
you can't turn a gas into liquid by compression alone if temperature is above critical point, you also need to cool it down. separation is done by fractional distillation, but the reason it's done is mostly about oxygen (medical and steelmaking among some other uses). for nitrogen it's somewhere about -150C. first air is stripped of water and carbon dioxide, then it's turned into a liquid, then it's separated into oxygen, nitrogen and argon, and some large specialized plants also separate xenon, krypton and neon
if you don't actually care for it being a liquid, there's another method called pressure swing adsorption that separates gases based on how tightly do they bind to porous surfaces under pressure. this is how medical oxygen concentrators work
making liquid nitrogen is pretty efficient these days, as in not much more energy is used than is actually needed
Maybe cool the planet with it.
easy, just cause 1 or more supervolcanoes to erupt. or a large asteroid throwing dust into the air.
TL;Dr but the gif looks really cool
Cool.
