Is this possible ?
Is this possible ?
(OP)
Humid air contains more energy than the same amount of
dry air and water at the same temperature.
Would it be possible to take humid air ( e.g. at sea )
compress it, with heat exchenger cool it, precipitate
the water and recover the energy from heat and pressure
to drive the compressor.
Would this be useful for producing clean water?
Perhaps even end up with some energy left over ?
dry air and water at the same temperature.
Would it be possible to take humid air ( e.g. at sea )
compress it, with heat exchenger cool it, precipitate
the water and recover the energy from heat and pressure
to drive the compressor.
Would this be useful for producing clean water?
Perhaps even end up with some energy left over ?
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>





RE: Is this possible ?
RE: Is this possible ?
The difficulty comes from your second step. You want to start with humid air (which does have more energy than the equivalent amounts of dry air and liquid water). You then compress this air. This is an energy intensive step, and inherently/practically has a fair amount of irreversibility (lost work) to it. Now comes step two - cool the compressed air. This removes much of the energy contained in the compressed humid gas, especially if accompanied by condensation. Furthermore, it is likely heat that will be rejected as waste heat to atmosphere or some heat sink. So what energy will you recover? The only energy to recover is what I've called "waste heat". That has low utility since its temperature will likely be quite low; it is not likely to be a source of useful energy. While I hate to sound so negative, I cannot be optimistic about this. Try analyzing the overall process using the second law of thermodynamics.
Doug
RE: Is this possible ?
The heat could be pumped from the compressed humid air to
heat up the dry air. I realize that efficiencies are
important but even if there is some energy loss,
it may be useful to make clean water if it require
less energy than distillation.
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: Is this possible ?
RE: Is this possible ?
To cool, you have to compress some gas so why not use
the air itself?
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: Is this possible ?
why will the water be clean ? won't it have all the impurities (junk) that's floating around in the air now ?
and how much water are you looking to produce ? i don't know the %age volume of water in humid air, but i'm willing to speculate that it's not much.
we've speculated that this process isn't efficient, you've responded that maybe it is more efficient than distillation. maybe it is, maybe it isn't, maybe no-one has thought of this process before (i think that's unlikely), but certainly people have invested in distillation plants and i think they'd've considered the alternatives.
but what the heck, give it a whirl and see what happens.
RE: Is this possible ?
I don't think it would be too hard to show that the whole process violated the 2nd law, though. Whip out that Thermodynamics textbook and go to work.
RE: Is this possible ?
Thermal energy storage is another possibility.
Condensing water to drink out of air is a known technique. It is taught in survival schools, often called a "solar still".
I believe that sailing ships of yore collected the morning dew from the sails.
RE: Is this possible ?
And by the way there is no violation of the 2nd law of thermo, only the uselessness of the form of energy you have extracted.
RE: Is this possible ?
You still have the purity issues to deal with, and I know nothing is free, but as clean water becomes less and less available this might be an interesting process to explore.
I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI
RE: Is this possible ?
RE: Is this possible ?
I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI
RE: Is this possible ?
When you get rich and famous don't forget the little guys out there bangin around these fool hardy notions.
I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI
RE: Is this possible ?
Humid air at ambient temperature comes in.
Dry air at ambient temperature (perhaps colder) goes out.
Water at ambient temperature goes out.
Heat goes out.
And is that process possible? I think not.
For that matter, if you have a black box that sits there sucking in humid air and putting out heat all on it's own, let's just hook it up to a steam engine and get some free energy off that heat while we're at it.
RE: Is this possible ?
A typical thermopile requires the temperature of a burning fuel to generate electricity.
TTFN
RE: Is this possible ?
So if you are going to condense water out of air, you should probably target cool humid air that requires slightly less energy removal to condense.
RE: Is this possible ?
I was engineer for 30+ yrs, got 10+ patents which is not enough to be famous. For that you have to be a singer
or football player.
I used "clean" as shorthand for "reasonably saltfree
to be usable for drinking or irrigation"
Jstephen:
The mixture of oil and water has higher entropy but still
separates sponteneously.
The humid air has latent heat, too.
ALL:
Would the efficiency ( friction,heat losses ) be
better if it were scaled up?
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: Is this possible ?
TTFN
RE: Is this possible ?
But alas, we must add in losses. As you are likely aware, mechanical methods are lossy, so calc your transport load, then add your losses.
If you had a waste heat source available, you'd have your transport energy.
attaching some form of your idea to an energy waste stream may actually decrease it's 'wastefullness'. You'll still be consuming but the net result may have benefit.
RE: Is this possible ?
Here the solar heat and condensing humidity is used to generate power by creating an artificial tornado is a stack.
Best regards
Morten
RE: Is this possible ?
Nothing about this process is "perputual motion", it would require a huge energy input.
David
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
The harder I work, the luckier I seem
RE: Is this possible ?
RE: Is this possible ?
Would a star an acceptable expression of thanks?
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: Is this possible ?
just another skeptic ...
RE: Is this possible ?
" and Mr. Michaud has found a way to realize it"- but in fact it seems Mr. Michaud is a long ways from realizing even his idea.
The original cycle is very close to running an evaporative cooler in reverse, for what that's worth.
RE: Is this possible ?
The automobile use didn't workout so an attempt was made to use it in a mode similar to original post, cool the house and get potable water. My last information was that work was continuing but results had been as expected.
As for trapping water it is being done on a very large scale in Chile and Peru using fine mesh nylon nets as collectors tied to a central cistern. It is giving thousands of people clean fresh water for the first time.
As for the water collecting on a sail as you will definately get wet standing under a sail if the boat isn't moving too fast.
RE: Is this possible ?
The condensate will be water with all the impurities from the air & process (non-potable) & will have contamination from the compression process (possibly oil).
The amoung of energy used in compression, cooling the heat exchanger (pumps), a source of cooling for the heat exchanger either sea water or some form of fridge take energy away from the mass of compressed air.
The amount & form of energy left in compressed air has to be less that that invested in the system & has to be in a usable form - essentially any compressed air "motor" is inefficient as it kaes air at one pressure & releases it to atmosphere in one pass.
Energy is used & not multiplied or for that matter easily stored.
Bruce L Farrar.
Works Engineering Manager
Marshalls Mono PLC.Brookfoot Works.
Halifax W.Yorks UK
RE: Is this possible ?
http://www.wataireindustries.com/
They even have residential units. They have quite a bit of information on their site.
RE: Is this possible ?
http:/
RE: Is this possible ?
Refering back to the original question this product is not quite the same in terms of recovering energy to drive the device (which simply cannot be done due to inefficiencies)
One question that puzzles me still is that the atmosphere contains all sorts of contamination (one in particular legionella is present in most of the air we breath - its only when it becomes waterborn, is incubated, then atomised into droplets breahted by susceptible people a problem arises)
How does the system overcome this contamination ?
Commercial fresh water generators (evaporating or distilling) sea water into fresh potable water have to take the water past 180 deg f & have certain restrictions if the sea water contains effluent (as most coastal water does) - simply passing the water condensed by refrigeration through filters etc etc - I will get some data from the makers & update my head with the latest technology !!
I am interested as to how much power these units use in electrical terms & whether these are used in marine environments - as the system gets around the destruction caused by sea water - the marine engineers curse !
Bruce L Farrar.
Works Engineering Manager
Marshalls Mono PLC.Brookfoot Works.
Halifax W.Yorks UK
RE: Is this possible ?
http://en.
There are plans to use the temperature differential between shallow and deep water to generate power. Honestly I've never heard of it actually being used, but we'll see what happens as oil $ continues to rise.
RE: Is this possible ?
RE: Is this possible ?
I think this project was like the Oil Shale project out west, it got over fertilized with money and died.
Anecdote:
I was instrumental in purchasing an all SS centrifugal compressor leftover from the Oil Shale Project. It was brand new in the box and only 10 years old. There was a very good discount on it.