Old is always gold keep it on, and plz bring it to the work
A centrifugal spin on a 500-year-old air compressor design
11–20 of 64 posts
Re: A centrifugal spin on a 500-year-old air compressor design
#12Interesting. A few questions that come to mind: 1. What is the dew point of the compressed air? Many applications using compressed air require very dry air so as to avoid corrosion issues (e.g., air tools) as well as problems related to heating of water vapor (e.g., tires). For small applications, the dew point is reduced using simple traps, silica gel beads, or molecular sieves, but for even-drier air or larger appl…
300 bar air.. Are you filling scuba tanks?
The wet air question is an interesting one. It seems like the compressed air would have more moisture in it than a piston-driven compressor, but at the same time having oil-contaminated air is problematic for moisture removal systems, especially dessicant-based ones. So you might need more thorough moisture removal, but with the dryer system having more life.
As far as efficiency goes, it's hard to tell because it's mostly a paper-company at this point and they don't have much in the way of product. Another press release mentions they can provide large volumes of air which usually translates to efficiency. The major source of work done in their system is to accelerate the water, so if you want more air, accelerate more water. It sounds pretty efficient to this armchair critic.
The other press release mentions they are targeting 10hp and 20hp systems, and 100hp systems are feasible. I'd imagine 10hp is where industrial compressors start.
[edit] Found a press release from 2014 where they claim better energy efficiency than conventional methods. This really does sound like a breakthrough.
Re: A centrifugal spin on a 500-year-old air compressor design
#13Interesting. A few questions that come to mind: 1. What is the dew point of the compressed air? Many applications using compressed air require very dry air so as to avoid corrosion issues (e.g., air tools) as well as problems related to heating of water vapor (e.g., tires). For small applications, the dew point is reduced using simple traps, silica gel beads, or molecular sieves, but for even-drier air or larger appl…
I didn't realize that air compression hardware has to deal with water removal but apparently it does. One article I found is suggesting that air at 7 bar can hold about 1/3 as much water. What confused me is that the a wing stall (low pressure above a wing) causes cloud formation, due to vapor condensing out of the air. But 7 bar is ~7 times as much air per cubic centimeter, so that's 14% as much space containing 33%…
>you're going to wash the particulates through a fluid that stays in the pump permanently, so how quickly is the funk going to make that compressor unpleasant to be around?
Yeah, I was wondering about that too. But is the water going to be there permanently?
If the input air is quite dry, presumably (total guess) it would pick up some extra water. So you'd need to supply more. And probably not just tap water because of dissolved minerals and so forth - distilled seems like a better idea.
Conversely if the input air is humid, you might end up condensing water out of it, and need to bleed water from the system.
And then you're dissolving particulates in it either way...
All sounds like maintenance work, but maybe not a prohibitive amount of it.
Re: A centrifugal spin on a 500-year-old air compressor design
#14I suspect that Carnot is aiming to compete with liquid ring compressors https://en.wikipedia.org/wiki/Liquid-ring_pump, which have much of the same advantages and disadvantages (near isothermal compression, water saturation). I'm guessing the article didn't mention this because every home compressor user wants a less noisy one and they get better propagation of the article around the internet that way. I considered building a centrifugal trompe a while ago for a project of mine, mainly because its really hard to find sub-horsepower liquid ring compressors, but frankly my experience with DIY centrifuges has been explosively scary.
You can run a pump like this with kerosene instead of water, in order to reduce the amount of saturated vapor that comes out with the compressed air, but that can also cause certain flammability concerns. I once had one of my homemade vacuum pumps blow kerosene all over me when a gas bubble entrained a lot of fluid. This is one of those reasons I don't smoke - it can kill you.
Re: A centrifugal spin on a 500-year-old air compressor design
#15I suspect that Carnot is aiming to compete with liquid ring compressors https://en.wikipedia.org/wiki/Liquid-ring_pump , which have much of the same advantages and disadvantages (near isothermal compression, water saturation). I'm guessing the article didn't mention this because every home compressor user wants a less noisy one and they get better propagation of the article around the internet that way. I considered…
Could you do it with mineral or tool oil?
Re: A centrifugal spin on a 500-year-old air compressor design
#16Interesting. A few questions that come to mind: 1. What is the dew point of the compressed air? Many applications using compressed air require very dry air so as to avoid corrosion issues (e.g., air tools) as well as problems related to heating of water vapor (e.g., tires). For small applications, the dew point is reduced using simple traps, silica gel beads, or molecular sieves, but for even-drier air or larger appl…
I'm certainly no expert, but as they pointed out this is basically a trompe, which... >Compressed air from a trompe is at the temperature of the water, and its partial pressure of water vapor is that of the dewpoint of the water's temperature. If the water is cool, the compressed air can be made very dry by passing it through pipes that are warmer than the water. Often, ordinary outside air can warm the pipes enough…
> this is basically a trompe
Is it though? They don't really explain how it works or show any diagrams, and they said it was "inspired by" the trompe. So I'm a bit confused on that point.
It really looks more like a mashup of a centrifugal compressor and a diffusion pump. One where water instead of oil is used as the working fluid.
Re: A centrifugal spin on a 500-year-old air compressor design
#17I suspect that Carnot is aiming to compete with liquid ring compressors https://en.wikipedia.org/wiki/Liquid-ring_pump , which have much of the same advantages and disadvantages (near isothermal compression, water saturation). I'm guessing the article didn't mention this because every home compressor user wants a less noisy one and they get better propagation of the article around the internet that way. I considered…
"isothermal" is the reason this system is more efficient right?
But is it the theoretically most efficient way to compress air? Is there a (theoretical) way to compress the air adiabatic'ly (letting it heat up as you squeeze it), and do better overall?
Re: A centrifugal spin on a 500-year-old air compressor design
#18So by this same reasoning, adding a little water spray to the input of my air compressor, and a water seperator on the output, would reduce energy consumption since the water would absorb heat during the compression stroke making the compression closer to isothermal rather than adiabatic?
Do any commercial products do this?
Re: A centrifugal spin on a 500-year-old air compressor design
#19Am I the only one twitching and reaching for Close Tab when the video labeled atmospheric air intake as "o2"?
Re: A centrifugal spin on a 500-year-old air compressor design
#20Interesting. A few questions that come to mind: 1. What is the dew point of the compressed air? Many applications using compressed air require very dry air so as to avoid corrosion issues (e.g., air tools) as well as problems related to heating of water vapor (e.g., tires). For small applications, the dew point is reduced using simple traps, silica gel beads, or molecular sieves, but for even-drier air or larger appl…
300 bar air.. Are you filling scuba tanks? The wet air question is an interesting one. It seems like the compressed air would have more moisture in it than a piston-driven compressor, but at the same time having oil-contaminated air is problematic for moisture removal systems, especially dessicant-based ones. So you might need more thorough moisture removal, but with the dryer system having more life. As far as effic…
The work done accelerating the water doesn't seem to be recovered anywhere...?
I would assume that to get any kind of respectable efficiency the high pressure water needs to go through an energy recovery turbine before being cooled and reused.