PDA

View Full Version : Boiling water



ScatterPlot
07-16-2002, 04:20 PM
OK, now I'm not sure if this forum is for paintball tech only or not, so here goes.

-Please don't delete this, it sounds minor but is part of a much more technical project I am working on, and here I can get the kind of help I need.-

What is the most energy efficient way to make water into steam? I need to be able to use a small generator to do it. The water will be condensing on something above it, so I could use something to take heat from that. So please tell me how I can do this
Thanks
Bert

Coaster
07-16-2002, 08:04 PM
the sun :)

rjvemt1
07-16-2002, 08:29 PM
is it a 110 volt generater?i think the simplest way to do it would be to use an electric stove burner(with temp dial).what are you trying to do, make drinkable water in a wilderness setting?

Death Doctor
07-16-2002, 09:39 PM
Sounds like moonshine to me :p

rjvemt1
07-16-2002, 09:50 PM
allright, now that yous seen the still we is gonna haves ta kills ya!:D

314159
07-16-2002, 09:55 PM
you take a toster, plug it into the wall next to the bathtub (if you have one of thoes gfi sockets you are f***ed unless you have an extension cord). fill the bathtub half full of water, and drop the toaster in your lap. ;)

why do you care for efficency, why not just say to hell with it and use energy courtesy of the electric or gas company.....

(if you give us a hint or tell us what u are dooing, you will get better sugestions):P

Aranarth
07-16-2002, 11:48 PM
Agree with PI. What are you attempting to do? Are you making a simple heat transfer device, or are you making something to get pure water?
Just for a simple pure water though. I'd use the steam generated to heat the water you feed into it. Use that excess heat. Don't expect huge efficiency though. Heat engines have poor efficiency.
Do a search on the net. Some things you might use are heat engines and carnot cycles. Might give some luck.
Then there's always the trick of digging a hole and using some black plastic bag over it with a rock in the center over a cup. All it takes is the effort to dig the hole. Might be considered efficient, if not mechanical. :)
-AranarthX

ScatterPlot
07-17-2002, 12:07 AM
Im trying to make something that cycles water through some stuff (non contact) and then plops it in a bucket. The thing it goes through generates some current (cant explain now, too much time) and I need a way to get the water back to the top. I was thinking I could use the current from the machine to boil the water, and let gravity lift the steam to a thing on the top where the water would condense. So I REALLY do need efficiency, not just want it. Oh yeah, what was with that toaster thing? Kinda random

nerobro
07-17-2002, 01:54 AM
Putting ANYTHING through a phase change is not efficant. You're best off with a pump. even if you did go with boiling the water, to keep that process efficant you'd need to do something to recover the heat you put into boiling it... that's going to require coolant and pumps as well.. (thinks about it) or a well primed system so a siphon effect would hual water through the heat exchanger.

IT comes down to, unless you have a LOT of waste heat, boiling water is not efficant.

bjjb99
07-17-2002, 07:18 AM
Get a narrow band microwave emitter tuned to a strong absorbance line of liquid water, shoot it through a water filled tube, and you'll get steam. Good coupling between the microwave energy and the water molecules results in decent energy transfer. As for the efficiency of the emitter, no idea.

Pass the water across an array of nuclear fuel rods placed sufficiently close together to result in controlled fission. Assuming the rods are completely submerged, you will get good thermal energy transfer to the water, boiling it. You can keep boiling water with little regard for efficiency until the NRC, FBI, and a few other groups come knocking on your door (assuming you're in the USA).

> The thing it goes through generates some current (cant explain now,
> too much time) and I need a way to get the water back to the top. I
> was thinking I could use the current from the machine to boil the
> water, and let gravity lift the steam to a thing on the top where
> the water would condense.

You're not talking perpetual motion machine here, are you? After all,
you did mention using the current generated by your device to bring
water back to the top of the system, where it can be used to generate
current again...

BJJB

ScatterPlot
07-17-2002, 10:37 AM
Perpetual motion, hmm... interesting thought.
Probably not perpetual, but it would last a pretty good while, plus look cool just ticking away like that for a while. I dont really want to turn this into a debate pver whether or not it can be done, cause I think it just might be able to. I always try to think open minded about stuff like this. If we dont get it now, we will someday. An example of thinking ahead too predictively will end you up like the Disney show on lasy night called Magic Highway, USA. They had the entire highway building system worked out, complete with cars that were automated, and you told where you wanted to go with your punch card, then your car would go by itself on a nuclearreactor so it didn't need to be refueled and so on and so on and so on. Im not complaining about the technology one day being availible, but come on, punch cards!?!? I dont think we should predict the future too certainly.

SlartyBartFast
07-17-2002, 11:09 AM
Impossible to get into a debate about perpetual motion. Because it is absolutely impossible. The universal law of entropy rules it out.

It is absolutely impossible to create any process which is 100% efficient. Whether to friction or other lost heat, that means there are always losses. Therefor all processes real or imagined will need input of some power to continue running.

To address the initial question, the most efficient way to boil water is with a high efficiency gas water boiler.

But in this case, whatever the machine, there will be large energy losses during the water boiling and large energy losses during the condensation.

Has nothing to do with being open-minded or not. Have to face reality.

As for the Disney idea, seems rather feasible to me. It only suffered from two errors. The rather pathetic past love affair with nuclear power thinking it was cheap and clean (both wrong) and not being able to guess at future computer technology. Punch cards seem to be a better guess than voice control. They guessed that computers would be capable enough but had the forsight to realise that voice recognition is decades away.

ScatterPlot
07-17-2002, 11:17 AM
Actually, the lawys of physics apply to the PHYSICAL world, not the quantum world. In the atomic world, im pretty sure the electrons keep moving. But, egads! No energy input! It stays the same.

SlartyBartFast
07-17-2002, 11:23 AM
Well, perpetual motion machines are firmly planted in the physical world. So I don't think any kind of side track to quantum physics is of any use.

Besides, electrons receive and give off energy all the time. Is there proof that the energy consumption of an electron is zero?

The universe is slowing down and cooling, the stars are all slowly dying.

If the universe isn't perpetual, can't expect any man-made thing to be.

Aranarth
07-17-2002, 05:34 PM
Nuclear power is not cheap by any means. But its very clean, as compared to fossil fuel power supplies. Sure, can't compare to solar, hydro, and wind. But of those three, hydro is the only one currently able to give huge outputs, and it requires a bit of terraforming to do.
But as nerobro said, putting anything through a phase change is inefficient. If you don't need the heat for anything specific, heating something is always bad, because you have to get rid of the heat somewhere. Waste heat is wasted power. Though if you insist on the heat idea. Have you considered not boiling the water? Given a closed system, if you heat water at the lowest part of the system, and cool water at the highest part, you get a thermal cycle which makes the water flow due to differences the density of the water as it heats up. Pumpless flow. Works pretty good, but you aren't going to get enough flow do push anything like a turbine with it.
-AranarthX

rjvemt1
07-17-2002, 06:10 PM
The thing it goes through generates some current i thought you already had a generator
I need to be able to use a small generator to do it. or is your doohicky the gen. that you where referring to?
Then there's always the trick of digging a hole and using some black plastic bag over it with a rock in the center over a cup. All it takes is the effort to dig the hole. dont forget a source of moisture(gras,non-potable water,urine...)

314159
07-17-2002, 06:53 PM
Originally posted by bertmcmahan
The thing it goes through generates some current



Originally posted by rjvemt1
i thought you already had a generator

maby he wants to route the output to the input and make a bomb.... a really big bomb ;) how a bucket fits into all of this i do not know, but what i do know is that it must be evil ;)

seriously, just tell us what you are trying to do

rjvemt1
07-17-2002, 06:58 PM
all this secrecy does have a very sinister ring to it;) or maybe he works for the gubment:D

ScatterPlot
07-17-2002, 10:56 PM
Here we go, I got the site I saw it on. http://amasci.com/emotor/ikelv.html Not perpetual motion, but possibly goes for a long time. The heat would be added at the bottom, and removed at the top- maybe use the heat from the top to go to the bottom. You could suck a pretty good bit of current out of it if you had one really big, maybe three stories. By boiling the water I use atmospheric pressure to lift it. Pumps would be good for going like a few feet, but once you get high up its harder for the pump to work. With the boiling idea at some point you use less energy to boil the water than to pump it really high. Sorry I didnt have the site sooner, I just couldnt really explain it on my own and didnt realized I had bookmarked it.

Aranarth
07-18-2002, 04:38 AM
Ditch the idea of a heater, either submerged or stovetop type. They draw a lot more current than the microamps this talks about, even when stepped down from the 'high volts' this outputs.
-AranarthX

Teenkertoy
07-21-2002, 12:01 AM
I think you're on the topc of an "waterdrop electrostatic generator". I have a few links that explain it a little more with better pictures. If you've never seen one in action, it's freaking cool.

http://www.newphys.se/fnysik/3_1/kelvin/
http://www.angelfire.com/ak/egel/kelv1.html

These are all links to websites I've found becuse I was once interested in building one myself.

Is this even close to what you're talking about?

~Teenkertoy

ThePatriot
07-21-2002, 12:37 AM
Well...why not use a very simple design? If i read this right you are looking for the most efficient way to move water around...why not get an air pump and pump one of of the tube, and create a syphon. I believe that would be very efficient, but i probably have the wrong idea.