Hacker News new | ask | show | jobs
by DannyBee 1875 days ago
Speaking as someone who uses compressors both for shops and breathing air - this is mostly non-interesting so far. For starters, 70db is actually pretty horrible.

Indoor Scroll Compressors are around 47db (IE 100-1000 times quieter than the 70db mentioned here). They are completely oil-free and produce class 1/class 0 air. That is, you can use them to breathe from They are not as energy efficient as rotary screws, but it's only off by about 20%.

In practice, the flow of air into a tank produces way more noise than the compressor itself with these.

Even rotary screws are around 60-65db, and there are both oil and water cooled versions. They are very energy efficient, and due to the design, can be put on VFD's and modulate air-demand incredibly well.

Oil carryover is typically <3ppm, and you can use oils meant for incidental food contact/etc or filter it down further.

Both the above have 100% duty cycles. They can be on continuously (and in fact, oil-flooded rotary screws get unhappy if they are used too little).

Without more, or at least, based on what this article says, it's really hard to see what part of the market this thing will inhabit. They also don't talk at all about how to modulate them, what their duty cycle is, etc. Nor the dewpoint, etc.

1 comments

The trompe article goes into a bit more detail that might be of interest. You apparently modulate a trompe by changing the height of the intake and to some degree it’s diameter. I would assume that you modulate the Carnot device by changing the speed of the drum.

I am no expert here so I am making the assumption that perhaps the innovative part here has to do with using fewer moving parts than existent solutions, and potentially naturally producing cool dry compressed air without any oil mixed in. The idea of fewer parts/nothing but the air filter, belt, fan, maybe drum bearing to ever replace I’d quite appealing to someone who only has access to a pancake compressor that’s loud as all hell.

Yeah, this really does not sound like an energy efficient way to modulate down.

It's similar to some of the ways you see here: https://cascousa.com/compressed-air-101/types-of-compressors...

As for fewer moving parts and less maintenance, probably not gonna win on that. The state you want already exists. If you get a rotary screw, you are basically just going to replace oil and filters every so often until the air end dies. For a hobbyist, maybe never.

You might never run it for the 8000 hours the oil lasts or the filters last. If you ran it 3 hours a day, it would take 7 years :)

If you want simplicity and less moving parts, and the ability to fix them easily, you can get a rotary vane compressor.

They can't be modulated down as well using a VFD as you can a rotary screw (there is a minimal speed at which the vanes seal properly due to centrifugal force) , but they are ridiculously simple and have very few moving parts. They are also easily repairable.

Until it literally falls apart, you will just need to replace filters and oil every so often, and some carbon blades every so often (50k+ hours) or so of usage. The compressor itself will probably last 100k-200k hours, and so, again, for a hobbyist, may easily outlive you.

It's just a motor, connected to a slightly offset spinning circle with blades (so that as it rotates, the offset causes it to form progressively smaller chambers).

Looks like this: https://aircompressorworks.com/wp-content/uploads/2017/10/v-...