Electrocaloric material makes refrigerant-free solid-state fridge scalable
spectrum.ieee.org
spectrum.ieee.org
This is better than the refrigerant cycle we're using now, sure, but I don't see how this is "solid state"
> “We can scale it because those elements we are using are already commercialized for other purposes.”
> For one thing, none of the present ceramics’ key elements are appealing for mass production. Lead is toxic; scandium is prohibitively expensive; tantalum is a conflict material in Central Africa and, Defay says, best avoided.
So it's not available with the current materials they need?
I think the idea is that there are actually two jobs going on, and one of them has been solid-state-ified: (1) cycling something between hot and cold and (2) ensuring emit-heat-to-environment happens separately from the absorb-heat-from-contents part.
In a regular refrigerator, refrigerant is pumped around doing both things at once, however we could imagine a system where there's two loops with a heat-exchanger: One small liquid+gas loop for refrigerant, and another silicone-oil loop.
Temperature delta can be increased by just putting devices in series. Cooling wattage can be increased by putting devices in parallel
Cooling wattage per electrical watt with a given delta-T is the figure that matters (effectively efficiency).
Yes, but depending on efficiency this can scale quite horribly. Multi-stage Peltier coolers, for example, used to be absolutely horrible in yhis regard - a two stage device would need to dissipate 100W at the high temperature side to provide just 1W at the cold side. (I remember doing the math for a project around 2016, don't know how much better it is these days.)
(*from 3 weeks ago on HN) https://news.ycombinator.com/item?id=38259991
"Using black holes as rechargeable batteries and nuclear reactors" (2023) https://arxiv.org/abs/2210.10587
That's so wrong it's hilarious.
For a write-intensive workload, SSDs certainly die much faster than HDDs.
Otherwise, HDDs die faster, but modern SSDs die much faster than flash memories made with old technologies, which can have a lifetime of 10 to 20 years, while few SSDs can be expected to have a lifetime much longer than 5 years.
Some of my hard drives that failed when that way, sudden unexpected disappearance from the bus, but most of them provided signs of upcoming disaster, which could likely have been averted if the signs were considered in a timely way.
The failure rate of the SSDs was much lower than the HDDs, but the means of failure was more troublesome.
I do have an Inland 1TB with garbage performance that I can't figure out why, but it was super cheap, so at least I didn't pay much for it.
Most of the time the SSD just completely stops, never to communicate with anything ever again. :(
"Read only" mode would be a welcome improvement. :)
hard drives store bits magnetically , ssd's store bits electrically. You could call both solid state if the SSD wasn't specifically named due to its close relation to dram and cache lines that need active power. I would also consider hard drives more solid than ssd's if you tested for how long each could resist entrophy if there was no source of low entrophy.
Ahh so the data on this cooler can be read without moving parts, interesting.
OP was talking about the definition of solid state in a broader sense. In that broader definition (useful outside of computer hardware) "solid state" could refer to the parts that don't require constant power to maintain state.
OP was demonstrating how the term could be reasonably used to mean different things in different ways meaning that "solid state" is not a very useful term in it's own, it needs context to be meaningful.
I never said data, I said state. If you're getting hung up where I said “written” just think “changed” instead.
> In that broader definition (useful outside of computer hardware) "solid state" could refer to the parts that don't require constant power to maintain state.
This particular “broader definition” is not used in any domain, nor is it at all useful.
Nor was OP talking about any domain outside of computer hardware. They were talking specifically about hard drives and SSDs.
> OP was demonstrating how the term could be reasonably used to mean different things in different ways meaning that "solid state" is not a very useful term in it's own, it needs context to be meaningful.
They were demonstrating that if you make up definitions arbitrarily then nothing means anything. Regardless, “solid state” is a well-understood term with a specific widely understood meaning in the domain we’re all obviously discussing.
there is already a perfect term for that:
nonvolatile
non·vol·a·tile [nänˈvälədl] ADJECTIVE not volatile.
computing (of a computer's memory) retaining data even if there is a break in the power supply
Is it correct to say that they're analogous to gases changing temperature as the pressure of the gas changes? i.e. not a continuous generation of temperature change, but a one-shot change between two temperatures that's dependent on the outside force (pressure/electrical/magnetic/etc.) and some inherent capacity of the medium? That feels like the only way one could take away the resulting heat, remove the outside force, and have the element end up cooling down to a lower temperature than it started out, but I am not a physicist.
> "High cooling performance in a double-loop electrocaloric heat pump" (2023) https://www.science.org/doi/10.1126/science.adi5477
> Electrocaloric effect: https://en.wikipedia.org/wiki/Electrocaloric_effect
It sounds too good to be true to have a refrigerator that generates energy, but I lack the education in quantum physics to understand why it would be unreasonable or impossible.
The peltier or Seebeck effect does just this. By heating one side of the element and cooling the other, you get a small amount of electricity. It's impractical and very inefficient, though.
Because you must cool one side, you have to have some sort of system to remove heat as quickly as you put it in. Active cooling with a fan requires too much energy, so you're left with passive cooling. As well, the amount of power you get goes down as the cold side gets hotter.
There are plenty of good uses, though. Old gas water heaters actually used an electronic circuit to control the gas. A thermocouple is placed above the pilot light and creates enough energy to trigger the solenoid valve. Many types of temperature sensors work in the same way.
Leaving capacitive effects aside and concentrating on secondary effects, it's been my understanding until now the electric field in a bulk dielectric is never 100% in sync with the applied signal as the field itself physically distorts the dielectric, as such nonlineararities are introduced into the signal as it's transferred across the capacitor and that they vary to some degree with the signal's (field's) frequency and amplitude. Nevertheless, it's never been very clear to me what happens at the molecular level that contributes to this nonlineararity.
Essentially, losses in capacitors are due to I²R in its electrodes, bulk resistive leakage within the dielectric as well as resistive impurities in the dielectric and that signal distortion is principally due to the intrinsic nature of the dielectric itself. That is, signal distortion is caused by the action of the field on the dielectric which physically distorts it, and although this action is essentially elastic the effective energy through the capacitor is never a 100% truly accurate analog of the applied signal in that group delay and related effects are introduced, and these contribute distortion (that is, energy essentially remains the same but the signal is changed albeit to a minuscule extent). This new work seems to indicate there are additional reasons for why capacitors contribute distortion to signals.
After reading this article it's occurred to me to question how much heat is actually generated within the dielectric by, say, nonelastic strain or deformation of its crystal structure (through molecular movement, phonon coupling losses and or whatever). Heat generated through actual dielectric deformation is energy and by conservation of energy it has to come from the input signal. Signal distortion will then occur by virtue of some energy changing into heat which then becomes subject to thermal inertia. In effect, energy through the capacitor can be lost and if reabsorbed [by adiabatic process?] into the dielectric’s field then the transferred signal will not precisely mirror the input, thus additional distortion is incurred. Moreover, I'd then contend that distortion harmonics introduced into the signal by the dielectric and its related processes are not only likely to be complex but also frequency and amplitude dependent, and would only be predictable with a full understanding of both the dielectric's electrical properties and the heat flow within and around the dielectric.
This mechanism may also account for why high-k ceramic capacitors are more lossy at higher frequencies (it also seems the only true distortionless capacitor would be the vacuum type where ε₀ is the effective 'dielectric').
I'd appreciate it if someone with a better understanding of these issues could enlighten me.