SoylentNews is people
SoylentNews
https://arstechnica.com/science/2023/11/capacitor-based-heat-pumps-see-big-boost-in-efficiency/
Various forms of heat pumps—refrigerators, air conditioners, heaters—are estimated to consume about 30 percent of the world's electricity. And that number is almost certain to rise, as heat pumps play a very large role in efforts to electrify heating to reduce the use of fossil fuels.
Most existing versions of these systems rely on the compression of a class of chemicals called hydrofluorocarbons, gasses that were chosen because they have a far smaller impact on the ozone layer than earlier refrigerants. Unfortunately, they are also extremely potent greenhouse gasses, with a short-term impact several thousand times that of carbon dioxide.
Alternate technologies have been tested, but all of them have at least one major drawback in comparison to gas compression. In a paper released in today's issue of Science, however, researchers describe progress on a form of heat pump that is built around a capacitor that changes temperature as it's charged and discharged. Because the energy spent while charging it can be used on discharge, the system has the potential to be highly efficient.
[...] For hydrofluorocarbons, the difference in heat content can be controlled by altering the pressure. Compressing a gas will heat it up while lowering the pressure cools it down. However, various other materials undergo similar heating and cooling in response to other external influences, including physical stress, magnetic fields, or electric fields. In many cases, these materials remain solid despite experiencing significant changes in temperature, which could potentially simplify the supporting equipment needed for heating and cooling.
In the new work, done by researchers mostly based in Luxembourg, the researchers focused on materials that change temperature in response to electric fields, generically known as electrocalorics. While a variety of configurations have been tested for these materials, researchers have settled on a layered capacitor structure, with the electric field of the material changing as more charge is stored within it. As charge is stored, an electrocaloric material will heat up. When the charge is drained, they'll draw in heat from the environment.
This has a significant advantage regarding the power needed for the device to operate since the current generated when draining the capacitor can just be used to power something. There's a little energy lost during the round-trip in and out of storage, but that can potentially be limited to less than one percent.
Journal Reference:
Junning Li et al., High cooling performance in a double-loop electrocaloric heat pump, Science, 16 Nov 2023 Vol 382, Issue 6672 pp. 801-805 DOI: 10.1126/science.adi5477
(Score: 3, Insightful) by RS3 on Monday November 20 2023, @02:50AM (4 children)
As an engineer, and very hands-on, reading your posts about the lack of product quality frustrates me, even though I know it all too well.
I generally observe, to a great extent, that older things were generally made better and last longer.
Over the years economics have pushed and pushed and squeezed engineers and designers to make things cheaper, cheaper, and cheaper still. The #1 thing I'm supposed to have on my resume is: how I cheapened something.
People love to talk about the energy efficiency of that new whatever thing. But nobody seems to calculate in the costs, including energy use and CO2 production, of making new ones of that thing, or repairing that newer thing, versus keeping that much older thing. It's all about short-term profit and/or energy efficiency.
A friend has a 1950s GE refrigerator in his late mom's basement. Several times he's talked about getting rid of "that old thing". Well, it still runs. As far as I know has never had service. It's dead quiet. It was designed and made when people took great pride in making quality products. Interestingly it has great market value now.
The evaporators and condensers you mentioned are great examples. They used to use much thicker copper tubing and aluminum fins. Way back they may have been copper fins. Now they're so thin they corrode and fail, sometimes within a year.
I have a 30-year old window AC that still works. I don't use it a lot, but one of the things I did to preserve it was to paint some of the internal parts, where they get wet at the bottom, with some anti-rust paint. Also I drilled a hole to allow the water to drain out in off season. I plug the hole for summer because the cold condensate gets sprayed onto the condenser and improves thermal efficiency.
My solution: if govt. wants to force higher efficiency heat-cycle products, I'm okay with that, but also force very long full warranties. Yes, things will cost more initially, but how nice it would be to have a thing last 10, 20, 30, or more years.
(Score: 2) by slap on Tuesday November 21 2023, @04:22AM (3 children)
Our house AC unit is 35 years old, and we live near DC so it gets used a fair bit in the summer. It still works fine, and hasn't been touched for servicing in about 10 years. While a new unit would be alot more efficient it wouldn't last nearly as long.
(Score: 2) by RS3 on Tuesday November 21 2023, @06:00AM (2 children)
That's pretty impressive. What brand unit?
If economics worked the way my Utopian fantasy wishes it would, someone would sell better / ruggedized things for those of us who prefer better quality. I don' t mean Bentley prices, but something reasonable for what it is. What saddens me is that as companies "optimize" (cheapen) products, they don't lower the price, rather raise the price, advertising "NEW!", and people don't have much choice about what they buy. I know someone who has a seashore vacation property and the outdoor heat pump units maybe last 5 years due to corrosion. I haven't researched it but maybe someone makes a unit that's more resistant to the salt air.
(Score: 0) by Anonymous Coward on Tuesday November 21 2023, @03:30PM (1 child)
I'd certainly pay more for a ruggedized house AC, if it was backed up by a long warranty (10 years or more). But it would have to be from a company that seems likely to stick around for the duration of the warranty. Haven't seen anything offered like this, but maybe it's out there?
Possibly related? The newer high efficiency units have much more heat transfer surface than older units. This means thinner fins, more fins, and more tubes to get the working fluid to the fins. These all sound like increasing the "attack area" for leaks and corrosion. Maybe it's the nature of high efficiency to have more leaks?
After several basement dehumidifiers lasting only 2-3 years (they leak and slowly quit working), we bought an extended warranty on the most recent one. Luck of the draw, this one is still doing fine after a few years and maybe we wasted that 10- or 15% extra cost of the warranty?
(Score: 2) by RS3 on Tuesday November 21 2023, @06:51PM
I wish you'd come out of hiding.
Yes, I forgot to mention, but I'm sure I did elsewhere recently, that 10-year warranty should be required by law. Things would have to be made better, and no more "fly-by-night" crap from nobody-knows-where with some old good recognizable but now defunct company's name on it.
Thermal efficiency:
- More surface area- yes, absolutely, pretty much intuitively obvious (to me anyway).
- Thinner fins: no, no, and no. The fins have to conduct the heat away from (or into) the tubes carrying the refrigerant, right? Thinner means LESS heat carrying ability. It's only done because CHEAPER.
- Okay, I'll give you that thinner fins allow more of them per unit area (volume) but as I'll mention further down, they fail sooner and the long-term net result is more waste, which is BAD for environment and overall efficiency.
- Oh, another thing: thinner denser fins = more clogging with dust and debris. So NOT good for efficiency.
- Thinner tubes: I'm not an ME but still very good with thermo. I'll state, unqualified but strong hunch that thinner copper tubes have immeasurable effect on efficiency. They're thinner because it's all about being able to make something that lasts just to the end of the warranty.
A good friend recently did a major research on dehumidifiers. He came up with commercial / industrial ones, some cost more than $1K, but are so efficient they'll pay for themselves, and typically last more than 10 years. I don't know the brand he chose, but he found them at Global Industrial. Some are "Global" branded. It's easy to do a web search and find them (search: "global industrial dehumidifier"). The warranties are not what I want to see, but they're made so well they'll last much longer. One feature many have: "rotary" compressor. Very little vibration, which (should be intuitively obvious) causes metal fatigue and cracks. One thing I notice a lot and hate: newer refrigerant compressors vibrate BADLY, compared to much older stuff. Friend's 1950s GE refrigerator: you can't hear the compressor running. Putting you hand on it, you can barely tell it's running. Designed and made before they figured out how to cheapen things.
Vibration + too-thin tubing = early death.
Finally to mention: the harmful refrigerants are getting into the atmosphere much more than they used to due to high compressor vibration and thinner tubing.