Water electrolysis HHO conversion. Thermodynamics

[bob102939]

I was going to post in the chemical section but not much activity over there. I was curious if HHO conversion has been explored in length here? Either as a fuel additive for automotive applications or for independent fuel?

Per my understanding, HHO is called "Browns gas" which is some magical combination of of H and O that stays in gas form. Per some research there might be some practicality to this for burning an intensely hot flame but that still raises the question, does energy in = energy out in this application? obviously there is an immense amount of energy in water but I was always taught that the energy to crack it is very high.

That, however, does not mean someone cannot re-write the book or find new ways around this. If the conversion makes practical sense, I would love to use this product for use in a steam generator but obviously if it takes more electric to produce the HHO than you get BTUs out, that jus does not make sense. I am wondering if the industry is already telling me the answer since this was developed way back in the 60s and still not being used....

Every month, I hear of some magician, non-engineer type trying to make wild claims that their car is running on water. I will believe it when I see it. Hydrogen burns VERY fast and probably would not make the ideal combustion fuel...

 

[GregLocock]

Last bit first. BMW have an internal combustion engine running on hydrogen.

Yes, using hydrogen as an adjunct to other fuels to improve efficiency or emissions has been widely explored, and not just by tin foil hat wearers. eg

http://www.mech.unimelb.edu.au/people/staff/harry_watson.html

It is possible that the improved efficiency of the total combustion process might exceed the energy required to crack the water in the first place, if the whole system is properly designed.

However, if you are talking about the efficiency of the process energy_in+water->H2+O2->water+work_out alone then the second law of thermodynamics is all you need. It will be less than 100%. It'll be 20% if you are very good at engineering or lucky, if you are burning the gas in an IC engine. it might be 60% if you use fuel cells etc.

An esteemed contributor here did try one of the tin foil hat brigade's devices, if you are lucky he might tell you exactly what fuel consumption improvement he measured. Clue, you won't be missing much if he doesn't.



Cheers

Greg Locock


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[ivymike]

not sure who the esteemed contributor is, but I tried it too (fully expecting that it wouldn't help). The argument was not whether it would work by itself as a fuel source (first law and second law conspire to prevent that), but that it might improve combustion of gasoline to make it burn faster and/or reduce unburned fuel (of which there should be very very little anyway). There were some papers about hydrogen enrichment to improve combustion of very lean mixtures in natural gas engines, so I humored the promotor and agreed to try it out. I keep very careful records of my fuel usage and track the data in a spreadsheet - every fillup since I've owned each of my vehicles, so it should have been easy for me to spot a big change. I bought an HHO generator from the peddlar, and installed it per his recommendations (w/PWM controller to adjust "excitement frequency" to optimize output! you can also use it to keep the current draw low enough to avoid blowing fuses). It makes lots of big bubbles when you turn it on. I kept the gizmo installed for 6 or 7 fillups. There was no observable difference in fuel economy. The guy promoting the devices changed his story a bit and suggested that I needed to also fudge the O2 sensor readings in my car to lean my air/fuel ratio, and that THEN I'd see the benefit of HHO. I didn't feel like breaking the law & risking damage to the engine and/or emissions equipment, so I just removed the device at that point. I've still got it if you'd like to buy it from me and try it out for yourself.

 

[bob102939]

Mike, that is precisely our take on the device. We used an ECM monitor device to compare fuel rate over speed to get the efficiency. We ran a few control tests on the highway, then added the device and tested again. There was no change at all. We were going to lean out just to see what happens by tuning the map sensor but decided against it.

I just decided I wanted to understand the physics involved in leaning out because a lean gasoline condition is one subject to detonation and Hydrogen also accelerates gasoline burn soooo, what does all that mean??? Sounds like piston damage from here...

Per my understanding though, this is not Hydrogen, but OxyHydrogen in a gas which I am wondering is some freak of nature....

 

[IRstuff]

I think these people make up the physics to suit their version of snake oil.

OH^- is a real ion, but normally only exists in solution with water. However, you can get a plasma with the free ions, but probably not inside a car cylinder, since it usually requires much less than atmospheric pressure.

TTFN

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[ivymike]

the HHO devices produce H2 and O2 separately, not HO ions. The ratio of H2 molecules to O2 molecules is 2:1 (just like in water) - no shock there.

 

[benta]

"Per my understanding though, this is not Hydrogen, but OxyHydrogen in a gas which I am wondering is some freak of nature...."

Oxyhydrogen is just H2 + O2, which of course is a gaseous mixture.

Benta.

 

[JSteve2]

If you make gas out of water and then burn it, if water is the product of the burning, then you must lose useful energy in that cycle. If the product is something having a lower energy level than water, then theoretically you could have some net energy there to recover. Unfortunately, water is a very stable, low energy molecule and is the typical result of burning hydrogen and oxygen.

I don't think the temperatures required to start spewing quorks out of the exhaust are going to be practical or even achievable. I do think Brown's gas is an anagram for Snake oil, but I haven't rearranged all the letters myself to be certain.

 

[IRstuff]

http://en.wikipedia.org/wiki/Brown's_gas#Fringe_science_and_fraud

TTFN

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[ivymike]

again, the snake oil salesmen have moved a bit beyond the simple first law and second law violators.

The arguments for HHO devices today seem to be based around improving combustion of the fuel you're supplying (by making it burn faster, more completely, with leaner AFRs, etc). Not all of those claims are necessarily bogus (very lean natural gas engines have been demonstrated to benefit from H2 enrichment). It's not as obvious that there's nothing to it, if you assume an engine development program around hydrogen-enriched lean combustion.

The clearly bogus bit is the proposal that you can slap a device on an existing vehicle and fiddle with the AFR to get something which still meets emissions and delivers improved fuel economy.

 

[bob102939]

Well, I guess in my peanut brain, my thoughts here were possibly that, like petroleum, water already contains a large energy density in potential energy that can be released thus recovering petroleum nets more energy than is used to acquire and use the fuel.

Possibly water can be looked at in the same way some day? i just don't think this is as simple as energy in = energy out because water already contains potential energy. However, the HO bond has proved extreme in our atmosphere but maybe there will be a day when we can easily crack water to extract the energy.

This might be similar to chopping wood. Takes less energy to extract the heat energy from the wood because there is potential energy (fuel) stored up in the wood.

Maybe I am a little off base in my thinking. Certainly not a chemical wizard, just trying to wrap my head around the principals.

Regarding combustion in an IC engine, I could undertand where H could improve the use of all the hydrocarbons in the fuel but I fail to see how accelerating the combustion rate would off any benefit. This is already the advantage of diesel. Slower burn gives a better conversion of that pressure to the crankshaft. I realize there are other reasons from the higher CR but just trying to make my point that accelerating burn rate in an IC engine might not be optimal.

I realize that the best situation for an IC engins is one in which you can fire the cylinder at 0 degrees or TDC and still achieve peak cylinder pressures at the right time. As of now, rates are still a bit slow so we have to add timing. By increasing the CR though, we can reduce the timing and get a better eff from the engine.

 

[IRstuff]

Wrong, water releases energy on formation, i.e., when you combine oxygen and hydrogen, you get an explosion. Therefore, it takes a massive amount of energy to crack water back into hydrogen and oxygen. There is no there, there.

TTFN

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[ivymike]

crack water to extract the energy.

The energy that is released when you burn hydrogen to make water is almost identical to the energy you need to put in when you "crack" water to make hydrogen.

For a physical analogy:
1) you roll a ball down a hill and it goes faster and faster as potential energy is converted to kinetic. ~ Burning hydrogen to convert chemical potential energy to thermal energy
2) If you want to roll the ball down the hill again, you must get it to the top of the hill, and this requires that you put in energy. ~ "Cracking" water to make hydrogen and oxygen requires you supply enough energy to restore the chemical potential energy which was released in step 1.

 

[BrianPetersen]

... and the inherent inefficiencies of every thermodynamic process (and chemistry follows the laws of thermodynamics ...) mean that you will actually get less useful energy back than you originally put in. In a system such as those proposed, typically MUCH less.

 

[bob102939]

We looked at Hydrogen before as a way to store up energy from a large wind generator. We built one at a friends place that is 30kw and can more than power the whole shop but we do not have a way to store up that large amount of energy and pressurized H does not make financial sense. Still looking I guess. Right now, if the voltage drops below usable levels, it takes itself offline. We are not going to grid tie it because the power company wants us to spend 30G in switching and then pay us .02/kw. no thanks....

Rather find a way to store energy. Obviously HHO is not feasible either because we are not effectively storing it. So far, the only thing that even half way makes sense is DIY lead acid batteries made in the shop and a LOT of them. 30k lbs of them... Then you look at the price of lead and none of it makes sense.

Sensible large energy storage,,,where are you??

 

[ivymike]

run one of these?

http://www.ice-energy.com/ice-bear-energy-storage-system

 

[bob102939]

Thank you. I have seen that device but unfortunately most of the load is electric motors so an AC will not help us. We need either some way to store electric energy or a way to convert the electric to a storable fuel. We have so far looked at hot water, H, Ethanol, compressed air, etc. Just really difficult to get the power density and volume up without spending irresponsible amounts of money.

 

[IRstuff]

"Sensible large energy storage"

Yup, that's the Holy Grail right there...

TTFN

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[dgallup]

http://www.duke-energy.com/power-plants/pumped-storage-hydro/jocassee.asp

 

[patprimmer]

A big water tank on the top of a nearby hill or suitable structure works fine, that is if you have pipeline access and room available to you on a nearby hill. Structures have to be VERY strong and VERY high to be useful.

You need a turbine to convert it back to electricity. That might be achieved with the pump used to get the water up the hill being used to drive the windmill when there is no wind.

Regards
Pat
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