You wouldn't have to pump below a 10% of an atmosphere to quickly dry your clothes (vapor pressure of water is 5% of an atmosphere at that temp).
To give an idea of how fast:
With a 1liter/sec STP air intake, you would extract ~1gram/sec of water so in 15min you would remove ~1kg of water.
I've done hundreds of solvent evaporations under vacuum (rotovap). The problem is you need a trap, or else solvents condense in the pump which causes your efficiency to go down. So now you need a heat pump or similar, now you're talking about a really complicated dryer. But it'd be efficient.
The output pump would really need to mostly pump water and vapor at the input and liquid at the output, but not to very low pressure... even a peristaltic might be doable (no rotary vane/blower needed). It was just a thought, I used to rotovap too so running through the calculations seemed like a fun idea.
But for those that can use it, it is indeed a great system.
I wish my TV could do that...
If I'm in a major hurry, mostly due to self inflicted procrastination, I'll point a regular fan at the rack as it dries.
And most bathrooms are small and often without a window.
Not a complaint, just pointing out that sun-drying is often not a real choice. Often it is.
A related thing often banned is external over-the-air antennas, protected by US federal law.
"The purpose of this Act is to prohibit real estate contracts, agreements, and rules from precluding or rendering ineffective the use of clotheslines on the premises of [b]single-family dwellings or townhouses[/b]."
One benefit of this is that your clothes last much longer.
You can use a lot of detergent to remove the last bacteria; but household detergents are a big source of water pollution.
> (...) The group put their soiled clothes in a pillowcase and threw it into the geyser’s cone. When it erupted, the clothes were sent flying over a hundred feet into the air. When they collected them, the churning, heated water had indeed cleaned them.
Drying clothes in the shade is also powered by the sun, because the air only has "unused" moisture capacity because it was heated at some point. To repeat the cycle forever it will need to cool down and then be heated again.
Never, ever seen one since, and a quick web search for 'drying tent' shows up nothing but kit for pot growers.
The idea sounds pretty neat but I wonder about longevity of the piezeoelectric transducers. A clothes dryer needs to last at least 7-10 years, minimum. A resistive heating element is about as simple as you can get, and it's cheap to replace if it does burn out.
If they'll wear out fast it's entirely feasible to design the dryer around user-replaceable piezos.
It may end up like with inkjet printers -- where the dryer itself is just a boring spinning drum with a fan and a moisture collector and a powerful piezo driver, and you end up buying consumable cassettes with the actual transducers inside.
Then just allow people to rent the devices (which would obviously cost more) rather that have to buy them outright.
Perhaps they can be legislated into existence... ;)
A Mars rover is a bad example here because it's not an item that is, or will ever be, mass-produced.
Guess I just need to start an appliance company and fail to become enlightened as to why my desire of quality and serviceability are unattainable ideals.
Incidentally, your comment on price is a weak argument, because the product doesn't even exist. Even the luxury appliances have tremendously low longevity now. So luxury at this point basically means it looks really good while it works and you can afford to buy another when it doesn't.
The difference in the longevity of my clothes -- same exact articles, same brand, same material, thickness, size and stitching -- from switching from a "hotbox" dryer to condensation dryer was initially amazing. No more did cuffs and collars start to crack and fail, nor did my shirts slowly develop small tears.
The latest (2014 is when they really started to hit the market) heat pump dryers dry clothes even cooler still, albeit since they're new tech they're quite a bit more expensive right now.
In Europe, a "condensation dryer" is so common, they're just called a "dryer", with no differentiating term. Additionally some countries (Switzerland I think) I believe don't even allow hotbox dryers anymore (and their needed conduit and vents) as part of fire/building code. Condensation dryers simply have a high quality lint filter (that truly does trap it all) and vent to atmosphere, since they just use a heat exchanger.
All while using far less electricity than simply heating things resistively.
I don't think I've ever seen one of these hotbox driers in person, but gathered somewhere that those had existed earlier and saw them as fully obsolete technology used only in some industrial settings. The fact that they are still sold and installed (with all the requirements) in ordinary homes is very surprising.
(Hint: if you buy a condensation dryer, buy one with a drainage hose, if at all possible. Unless you are a very punctual person, you probably won't learn to empty the water storage after every cycle despite that all the manuals tell you to do so, because it can hold water from several cycles – but you will find yourself having unexpectedly wet laundry from time to time when you start drying with an almost full water tank and are not near when the machine tells it can't continue the program.)
I wonder why dryers don't work this way, other than I think that it'd be much slower to dry as compared to a traditional dryer, and I'm not sure if you'd be able to wick the moisture out of ever fabric.
If a battery is a consumable, shouldn't it last only one charging cycle?
There’s no reason to introduce a new limitation unless the technology makes up for it in other ways. Having to replace a clothes dryer every two years would require the technology to be very good to justify such a burdensome task.
Or, a cost cutting measure of replacing a long-lasting ball bearing assembly with a shaft rotating in a vinyl cup which wears down to metal-on-metal like mine did after 3 years. Which is the sort of accelerated deprecation the OP was alluding to. Granted, the battery metaphor isn't great as energy storage tech is far from mature.
However, if you select the Samsung 7.5cf dryer, it also has free delivery. Of course, this is built into the price, and $550 for an appliance isn't pocket change.
also, where did they state the longevity?
The benefit reduces if you have a consumable component that needs changing, especially with the amount of e-waste that goes to landfill.
If my dryer was $50-$200 and could be carried in one hand, I'd be (grumpily) okay with it only lasting 2 years.
Pretty sure as soon as China is aware of this idea (if not already), they will have something in production and out the door faster and at a much larger scale than the US. Could someone explain why innovative ideas like this have to be published before they're actually built?
Looks Chinese to me.
I'm curious if the ultraound causes increased wear of the fabric at the thread ends, for example.
Good point! The water vapour needs a way out. That means a direct air path between the fabric and the outside world. They cannot seal the entire thing in a vacuum bottle to deaden the sound. I see a 50' pipe full of baffles, a giant truck muffler, between this thing and anyone with eardrums.
There are ultrasonic mist generators for cooling yourself down which probably work on the same principle:
and 500: https://www.youtube.com/watch?v=GlEfshsoyZk
If that really is the range they are targeting, this product is doomed. That will be one heck of a noise to cancel. "Soundproof box" is right up there with perpetual motion, zero-point energy, and spherical chickens in vacuums.
A clothes dryer, meanwhile, is a near-ideal case for vacuum isolation + elastic dampening. Build a box with a door; hang an airtight motorized barrel in the box from a bungee cord, with a second door, and electrical connection; and then, whenever both doors are sealed at the same time, [slowly] evacuate the air from the box.
They also directly mechanically couple the transducers to the fabric. You need as much area of transducer as fabric you need to dry, unless you have some automated way to place the fabric on the transducers sequentially.
Is the psychological effect of folding warm clothes rather than cold really that powerful?
They're concentrating too much on kWh. One could use the same technology and focus on variable electricity pricing. I want a dryer that I turn at night, and it dynamically turns on-and-off as electricity rates go up and down. It ends at a smooth tumble in the morning so I can put on my day's clothes and fold the rest at it's lowest wrinkle-point.
Probably the best solution is a cultural shift to air drying. I was very surprised that when I was in the UK, a place not known for sunshine, many air dried their clothes, while when I lived in the desert of Eastern WA nearly everyone used a drier.
And driers (and washing machines - which use a considerable amount of energy particularly if they heat the water internally) typically already have timer-start functions.
It also mentions that they're thinking of creating a tumble/drum dryer with these piezoelectrics. As opposed to a traditional tumble dryer that spins to aerate the cloths, I think the spinning motion would instead be required to pin the clothing against the piezoelectric lined drum (though I imagine it would need to stop and change direction periodically in order to expose different areas of the fabric to the drum wall).
Anyway, there are real health risks according to the World Health Organization:
"Food safety: Food safety is an important health issue. In a microwave oven, the rate of heating depends on the power rating of the oven and on the water content, density and amount of food being heated. Microwave energy does not penetrate well in thicker pieces of food, and may produce uneven cooking. This can lead to a health risk if parts of the food are not heated sufficiently to kill potentially dangerous micro-organisms. Because of the potential for uneven distribution of cooking, food heated in a microwave oven should rest for several minutes after cooking is completed to allow the heat to distribute throughout the food."
That sounds like nuking the surface of the food then waiting for it to cook after it has ben microwaved which may or may not fully achieve thorough cooking.
I found a washing machine with ultrasonic much more interesting:
Would be a little worried about stress on your clothes AND/OR Ears. http://www.sciencemag.org/news/2014/09/sounds-you-cant-hear-...