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HHO Gun possibility?

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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Unread postAuthor: THUNDERLORD » Mon Jun 29, 2009 7:36 pm

So what if it's "HHO" or "H2O2" Or IDK...call it "POOP"....
As long as it makes a "bang" like that who gives an eff???

Reminds me of "nitro-glycerine" being an incorrect terminology...
Nobody has cared for almost 200 years right?

BTW 1 More until post 1000!!!! WoooHooo 1K!!! :P 8)
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Unread postAuthor: inonickname » Tue Jun 30, 2009 3:51 am

Hydrogen can be compressed to a much higher ratio than gasoline. Take that into account. If you can make an oxy-hydrogen hybrid that uses pre ignition pressures much higher than 10,000 psi (they both liquefy way, way after that..).

Lets see you compress gasoline to those pressures. Oh wait..

Fair enough point that hydrogen could act as a 'booster' in a similar manner to a detonating cap to detonate secondary or tertiary explosives- using it's insanely fast flame propagation rate (close to twice that of acetylene, and not hard to get it supersonic.)

That said, I don't want DDT to occur in any car I'm driving.

And about hydrogen production for cannons on a larger scale, it's impractical. Think about a simple law of thermodynamics. You don't get more energy out than you put in. So therefore, if you use a 12v car battery as an energy source that's how much power you get in your gun. Minus the massive losses through wasted energy in heat during production, then the energy during combustion which doesn't actually go to propelling the projectile.. And larger scales start to look obsolete.

HHO is simply incorrect.

1) Hydrogen and oxygen are diatomic, hence they will always be (if they can) H2, O2, N2 and so on.
2) HHO would imply it's a compound. It's a mixture. It's not hydrogen oxide acid or something.
3) As has been mentioned, HHO is a rubbish term to imply that people selling these rubbish fuel kits for cars actually came up with something new.

Thunder, not to nitpick..

H2O2 is hydrogen peroxide. You want a mixture of 2H2 and O2, which is what comes straight out of electrolysis, assuming you don't do something stupid like use chlorine compounds as electrolytes.
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Unread postAuthor: Insomniac » Tue Jun 30, 2009 4:44 am

jimmy101 wrote:BTW, anyone interested in a store bought "HHO" (aagh, even Estes knows not to call it HHO) powered rocket might want to take a look at http://www.estesrockets.com/rockets.php?pid=001876
With a bit'o plumbing it could probably be used to fuel a spudgun. It's described as hydrogen fueled, which it is, but it also uses the generated O<sub>2</sub> as the oxidizer. Look up the patent for more details. The use of citric acid as the electrolyte is much safer than the often used lye or table salt. I wonder what the electrodes are made of?


I too am extremely curious as to what the electrode material they use is.

I want to figure out a design for a small, effective and most importantly safe H2/O2 generator.

The one I currently have uses two graphite electrodes (taken from dry cell lantern battery cells) and sodium bicarbonate as an electrolyte. I have a few problems with it though.

Firstly, the graphite electrodes (while they haven't needed replacing yet) arn't perfect. One of them (can't remember which polarity it is as I switch it around to keep the wear even) starts to flake away and degrade when used, so there are little dark specks in the water after using it. The only electrode material I've found that doesn't easily corrode is stainless steel, but I don't use that anymore due to the hexavalent chromium it deposits in the water.

The second issue with my setup is that it isn't producing gasses in the right ratios. I'm pretty sure that somwhere along the line I'm losing quite a bit of oxygen. If I electronically ignite a small amount of gas in a balloon underwater and manage not to burst it, the balloon is still partly inflated afterwards. Letting this gas out over a flame results in a pale orange, fast burning flame (Ie, it doesn't have the long, bright burn of somthing like propane, it 'whooshes' as it burns). I don't know why I'm left with this gas. I'm fairly sure it's hydrogen based on the way it burns, and the only reason I'd have extra hydrogen is if there wasn't enough oxygen to burn it. I don't think it's leeching out of the balloon as I'd expect the smaller hydrogen molecule to do so at a faster rate, which would leave me with too much oxygen. My best guesses are that it's somehow oxidizing the carbon leaving me with either carbon dioxide or monoxide, or combinging with somthing in the electrolyte. However this is all wild speculation and I don't have enough chemistry knowledge to know if this is plausable or not. (I suppose the heat of the combustion could also cause the latex of the balloon to decompose into somthing flammable but that seems a bit unlikely)

What would be a good combination of electrode material and electrolyte that would result in minimal corrosion of the electrode while still providing the right gasses and no dangerous by-products? I'm interested to know if nickel would work, because if I remember correctly it's the material used in the electrolysis cell on the 'deans benchtop' water rocket site. (I found a link showing how he made it, not sure where though.)
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Unread postAuthor: inonickname » Tue Jun 30, 2009 5:02 am

I recommend a different electrolyte. I've seen stated more than once that using sodium bicarbonate as an electrolyte will result in carbon-oxygens on the electrode, mainly monoxide and dioxide. It also rapidly eats electrodes.

I wouldn't be concerned with an average stainless steel. Not only is the chromium count quite low, it would take a fair tune of current for it to be released into the water. Though if your stainless is rusting then you should be concerned about the chromium.

The graphite electrodes will leave a lot of muck floating around.

Lastly, consider oxygen's weight compared to hydrogen. I haven't seen your unit, so I wouldn't know..I didn't have any problems with it on mine, but I had a constant water supply to keep 'dead space' minimal.

Edit: if you can get it, there's no going past platinum for electrodes. It is expensive.. It can be bought as wire which may be more cost effective than sheet.
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Unread postAuthor: Insomniac » Tue Jun 30, 2009 6:06 am

It's not sinking oxygen that's the problem... water level is usually very high (its a very small, very simple little cell). If bicarb's causing CO and CO2 to form, that would explain why I'm left with excess hydrogen... the oxygen's being used to form CO and CO2. I've seen people on youtube do tests for chromium in the water of their generators, and while theirs are generally larger and have been running for longer, I'd rather avoid using steel if possible. What other electrolytes would you recommend? I tried using citric acid and a couple of pencil leads to see how well they'd hold up (I don't have the cell on me at the moment, so I can't try it in that). The pencil leads fell apart quite quick, although I can partly attribute that to the fact that pencil leads arn't pure graphite, but a combination of stuff to make them work well in pencils)

Why does the sodium bicarbonate cause the CO2 and CO to form? Is it the carbon in the electrolyte forming the gasses, or is it carbon from the electrodes?
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I wonder how much deeper the ocean would be without sponges.
Right now I'm having amnesia and deja vu at the same time. I think I've forgotten this before.

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Unread postAuthor: inonickname » Tue Jun 30, 2009 6:23 am

Acid-base, or something during electrolysis. I'm unsure, and don't have proof, but it's been mentioned several times.

And yep, pencil leads are a mixture of low-grade graphite, wax and clay.

As for electrodes platinum is about as good as you can get. If you can find platinum wire then it would be easy to coil for use. I've seen copper listed, though never tried it.

As for electrolytes, there's a very large selection.

The following cations have lower electrode potential than H+ and are therefore suitable for use as electrolyte cations: Li+, Rb+, K+, Cs+, Ba2+, Sr2+, Ca2+, Na+, and Mg2+. Sodium and lithium are frequently used, as they form inexpensive, soluble salts.

If an acid is used as the electrolyte, the cation is H+, and there is no competitor for the H+ created by disassociating water. The most commonly used anion is sulfate (SO42-), as it is very difficult to oxidize, with the standard potential for oxidation of this ion to the peroxodisulfate ion being −0.22 volts.


Basically, salts of the above list.

If you didn't know, don't use chlorine compounds as electrolytes.
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Unread postAuthor: Insomniac » Tue Jun 30, 2009 6:28 am

Yep, already knew about the chlorine. I know from experience copper is aweful, degrades extremely quickly. I'll give citric acid a proper go somtime and see how it holds up.

Apparently platinum will as a catylist between hydrogen and oxgyen... one guy said he stabbed a h2/o2 balloon with a bit of platinum wire and it exploded instead of just bursting... not sure how accurate this is but if it is true that could be pretty useful.
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Unread postAuthor: inonickname » Tue Jun 30, 2009 6:32 am

Platinum acts as a catylist for the decomposition of hydrogen peroxide if I remember correctly. Infact, it's used as a monopropellant in rockets..

Let us know how the citric acid goes, I'm looking for something more friendly than NaOH. (I might give sodium carbonate a go soon, apparently it's very good)
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Unread postAuthor: daccel » Tue Jun 30, 2009 9:24 am

Haven't really read much on electrolysis, but what about using a platinum spark plug for electrodes? Cheap and easy to find.
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Unread postAuthor: jimmy101 » Tue Jun 30, 2009 11:53 am

Platinum is of course the best electrode material but unless you've got very deep pockets it is impractical. You can get fine gauge Pt wire for "sort of cheap" (Pt is roughly as expensive as gold :shock: ), but it really isn't useful as an electrode in a hydrolysis rig since you want the largest possible electrode area. Hence the use of plate electrodes in most serious electrolysis cells and liquid based batteries. A plate of Pt, even if it "foil" thickness is going to be pretty pricey.

A Pt spark plug has a very small electrode plated with Pt. The surface area is too small to be a practical electrolysis electrode. For even a fairly small cell you want at least several square inches of electrode area. That's also why carbon rods arent the greatest electrodes, their surface area is just too small and they generate H2 + O2 fairly slowly.

Pt is an excellent catalyst for H2 + O2. Introduction of a very small amount of Pt metal into a H2 + O2 mix will generally cause spontaneous combustion of the mix. This is a fairly common lab demonstration for the effectiveness of catalysts. Put a small amount of H2 in a bottle of air, drop a few granules of Pt metal into the bottle ... big bang. In chemical laboratories Pt is used to catalyze the addition of H2 to other compounds. Typically the Pt used is a 5% mixture on graphite. Very small quantities of the catalyst are used, usually less than a percent or so of the weight of the compound being hydrogenated, divide that by 20 to account for the "5%" nature of the catalyst and you get very small amounts of Pt used in the reaction. Often the catalyst is recovered because it is pretty $$$$.


The Estes hydrogen rocket patent is available online. It should describe the voltage, electrode material and the composition and concentration of electrolyte, but I haven't actually read it. http://www.freepatentsonline.com/y2004/ ... temming=on
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Unread postAuthor: jimmy101 » Tue Jun 30, 2009 12:05 pm

Insomniac wrote:The second issue with my setup is that it isn't producing gasses in the right ratios. I'm pretty sure that somwhere along the line I'm losing quite a bit of oxygen. If I electronically ignite a small amount of gas in a balloon underwater and manage not to burst it, the balloon is still partly inflated afterwards. Letting this gas out over a flame results in a pale orange, fast burning flame (Ie, it doesn't have the long, bright burn of somthing like propane, it 'whooshes' as it burns). I don't know why I'm left with this gas. I'm fairly sure it's hydrogen based on the way it burns, and the only reason I'd have extra hydrogen is if there wasn't enough oxygen to burn it. I don't think it's leeching out of the balloon as I'd expect the smaller hydrogen molecule to do so at a faster rate, which would leave me with too much oxygen. My best guesses are that it's somehow oxidizing the carbon leaving me with either carbon dioxide or monoxide, or combinging with somthing in the electrolyte. However this is all wild speculation and I don't have enough chemistry knowledge to know if this is plausable or not. (I suppose the heat of the combustion could also cause the latex of the balloon to decompose into somthing flammable but that seems a bit unlikely)

I wonder if it is a problem with the relative solubilities of H2 and O2 in water? If the O2 is much more soluble in water than the H2 then the water will trap a fair amount of it. Might want to google for the two solubilites. If it is a solubility problem then run the cell for a while to saturate the water with H2 and O2 then empty your collection chamber and run the cell some more. Once the water is saturated you won't loose any more O2 to it.

Insomniac wrote:I'm interested to know if nickel would work, because if I remember correctly it's the material used in the electrolysis cell on the 'deans benchtop' water rocket site. (I found a link showing how he made it, not sure where though.)

I seem to recall that commercial H2 generators use nickel plated electrodes, but I could be wrong. Might just try a couple of US Nickels. :D Perhaps a couple US quarters (silver over copper, coat the edges with wax or something to protect the copper edge of the coin). Silver is sometimes used as an electrode material. Silver is almost as inert as Pt and a lot cheaper.
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Unread postAuthor: jimmy101 » Tue Jun 30, 2009 12:09 pm

THUNDERLORD wrote:So what if it's "HHO" or "H2O2" Or IDK...call it "POOP"....
As long as it makes a "bang" like that who gives an eff???

Reminds me of "nitro-glycerine" being an incorrect terminology...
Nobody has cared for almost 200 years right?

1. People care because it is a sure sign of someone running a con job or of chemical ignorance. The "HHO" mixture has been known for a long time and has an accepted name, i.e., a 2:1 mixture of H<sub>2</sub> and O<sub>2</sub>.
2. Any chemical name that is 200 years old is never considered "incorrect". It is considered a trivial name and completely exceptable in chemical parlance.


that makes three posts in row oooops
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Unread postAuthor: jimmy101 » Tue Jun 30, 2009 12:17 pm

boyntonstu wrote:Copied from another forum and authored by a fellow 'HHO' idiot.

"First of all, with a fast initiator (like a brisant explosive charge)
and atmospheric pressure (etc.), the gasoline will win, big time. Why?
At atmospheric pressures and temperatures, gasoline vapor is much more
dense than hydrogen. Even though hydrogen has much more energy per
pound, gasoline has much more energy per unit of volume.

Now, simply a spark to ignite the mix and the hydrogen will be MUCH more
brisant, it will deflagrate or detonate with a bigger "bang" because it
has a much higher propagation velocity than gasoline. In fact, hydrogen
burns so fast, it may not need an initiator to be an FAE. If you look
at the experimental data on flame front propagation, the measurements
showed supersonic propagation of the flame front in a tube, which would
turn it from simple burning or deflagration (combustion that propagates
through a gas or along the surface of an explosive at a rapid rate
driven by the transfer of heat wordnet.princeton.edu/perl/webwn
<http>)

See this is one of places where people make big mistakes. Yes, there is a possibility of getting detonation instead of deflagration with H2. But that doesn't change the amount of energy released only how quickly it is released. In DDT you get very high shock wave pressures but that pressure lasts for an extremely short period of time, IIRC on the order of a couple microseconds. A shock wave is typically a fairly inefficient way to transfer energy from a gas to a solid. A massive high pressure shock wave can do a lot of damage. The shock wave in a couple liter volume of H2 only puts the container at risk, it's an awful way to try to actually transfer energy to a projectile or piston. In an ICE all a shock wave ("pinging") does is setup acoustic resonances in the engine which beat the crap out'a the bearings. The short pressure spike is much too short to be of mechanical use in the engine.
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Unread postAuthor: boyntonstu » Tue Jun 30, 2009 3:05 pm

jimmy101 wrote:
boyntonstu wrote:Copied from another forum and authored by a fellow 'HHO' idiot.

"First of all, with a fast initiator (like a brisant explosive charge)
and atmospheric pressure (etc.), the gasoline will win, big time. Why?
At atmospheric pressures and temperatures, gasoline vapor is much more
dense than hydrogen. Even though hydrogen has much more energy per
pound, gasoline has much more energy per unit of volume.

Now, simply a spark to ignite the mix and the hydrogen will be MUCH more
brisant, it will deflagrate or detonate with a bigger "bang" because it
has a much higher propagation velocity than gasoline. In fact, hydrogen
burns so fast, it may not need an initiator to be an FAE. If you look
at the experimental data on flame front propagation, the measurements
showed supersonic propagation of the flame front in a tube, which would
turn it from simple burning or deflagration (combustion that propagates
through a gas or along the surface of an explosive at a rapid rate
driven by the transfer of heat wordnet.princeton.edu/perl/webwn
<http>)

See this is one of places where people make big mistakes. Yes, there is a possibility of getting detonation instead of deflagration with H2. But that doesn't change the amount of energy released only how quickly it is released. In DDT you get very high shock wave pressures but that pressure lasts for an extremely short period of time, IIRC on the order of a couple microseconds. A shock wave is typically a fairly inefficient way to transfer energy from a gas to a solid. A massive high pressure shock wave can do a lot of damage. The shock wave in a couple liter volume of H2 only puts the container at risk, it's an awful way to try to actually transfer energy to a projectile or piston. In an ICE all a shock wave ("pinging") does is setup acoustic resonances in the engine which beat the crap out'a the bearings. The short pressure spike is much too short to be of mechanical use in the engine.


Yes, a slow blast like the fertilizer explosion in Oklahoma is a good example.

Would the increase in pressure caused by ignited H2 in a vessel be useful as a propellant?

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Unread postAuthor: Mateo » Tue Jun 30, 2009 6:47 pm

Yes, a slow blast like the fertilizer explosion in Oklahoma is a good example.

Would the increase in pressure caused by ignited H2 in a vessel be useful as a propellant?


it could be used as a propellant and it would probably work fine but its impractical to use on a large scale. where propane and butane are both easily accessible and cheap gases that can be found virtually anywhere. so what exactly the point of tirelessly pursuing this?

as for that whole car thing... its not a con. ive made my own and it works but not much. all it does is mix a flammable gas in the fuel/air mixture and then the computer sees that it suddenly starts burning better so it lessens the amount of gas injected into the mix. in the end it just replaces a bit of gas with a bit of hydrogen
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