And how will my cat react to this thing? Something with enough sonic energy to vaporize a significant volume of water is probably loud enough to wake every animal in the area.
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.
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 'soundproof box' is hard because most of those boxed things we want to quiet down (say, pets) still need to be a part of our environment, breathing air and the like.
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.
If you are going to go through all the effort to create a proper vacuum, and then isolate all the little penetrations needed to maintain whatever is inside, just throw the wet clothes into the vacuum and call the thing a freeze dryer. No sonic required. A heat lamp inside a vacuum chamber would probably dry stuff using much less energy than either sonic of hot air.
I'm not sure whether organic materials would be very happy with all their water content getting sublimated out of them due to the sudden drop in pressure. The result would probably look more like cotton jerky than fluffy towels. (If anyone has a Youtube link of such a reaction, though, I'd love to be proven wrong!)
That (the 600 Hz) is the modulation of the ultrasonic signal from the transducer...I am not sure if modulating the underlying signal at that frequency has a similar auditory effect as a simple 600 Hz sine wave.
Indeed that's what it says. That's neither ultrasonic nor easy to block with reasonable quantities of sound dampening materials.
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.
To get the effect they want they have to use high frequency 30-40kHz (as in name, ultrasound). They modulate it with lower frequency (which probably splits off bigger water globs) for better efficiency or something. You won't be able to hear the modulating signal as you are not able to hear the carrier frequency.
Yeah, maybe it's the frequency that some component runs at but not the produced sounds? Or maybe they forgot a "k" in "kHz"? Eyeballing a chart in their presentation seems to show 100kHz piezotronics. [Page 8 of https://energy.gov/sites/prod/files/2016/04/f30/31297_Momen_... ]
I'm not sure that we can make an accurate judgement based on that because it's going to depend on the mic they used, audio codec, (and less relevantly), speaker setup and hearing of listener.
I don't understand why this is such a valued aspect of dryers. All clothes coming out of the dryer for me go right into my drawers / hanging. They don't get worn at the very earliest the next day. I rotate everything so I'm not just wearing the same socks and undies over and over again, so the vast majority of the time they don't even get worn then.
Is the psychological effect of folding warm clothes rather than cold really that powerful?
Well, if you're using a hotbox dryer, it's not the hanging up while hot, but rather the fact that you just steamed and tumbled them. That gets wrinkles out of anything. Hanging up just keeps new wrinkles from forming.
I didn't realize this, but yes, this is absolutely true. I wonder how many people would actually be willing to pay a premium on having their clothes warm when coming out of a dryer.
Most of the energy consumption in a dryer is from the actual drying cycle -- once the clothes are totally dry, the high-temperature cycle to get them all hot doesn't consume much power.
I'm curious if the ultraound causes increased wear of the fabric at the thread ends, for example.