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Old 04-21-2012, 02:07 PM   #41 (permalink)
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Ok, I'd really like to understand what's going on here, so lets look at it a better way if we can please... as this data seems very confused.

Lets take a closer look!

This should really be simplified, as there seem to be many different arguments here.

1) the speed HHO/Hydrogen can be produced
2) the electricity required to produce it
3) how much the engine can actually use it, or if it can use it at all

Let's totally ignore those first two points for a moment, as that's something to overcome later, and it does not really matter if the third point proves HHO totally useless.

Now let's create a specific scenario to test the numbers. If when cruising at 60mph @ 2700RPM the car gets 50mpg (uk measurements), which is equal to 0.02 gallons used per mile. This equates to around 0.09 litres. Because we are travelling at 60mph we are doing 1 mile per minute, thus each minute the engine consumed 0.09 litres of fuel.

Say we use this on a standard gasoline engine. How much hydrogen does the car need in order to fulfil its supply needs? Simply put, if we completely forget about how to get the hydrogen in the first place and all the other factors and focus on one point at a time we might come to a conclusion more easily.

So, can a car (take for example my 1.8 litre 4 cylinder engine) actually use hydrogen in place of, or as well as standard fuel to carry out its normal operation?

Looking at Wikipedia, the energy density of Hydrogen is 0.01005 MJ/litre. Gasoline has an energy density of 34.2 MJ/litre.

At this point please forgive me if my maths is incorrect, I did not study Physics or Chemistry and am simply going from what I have learned myself since leaving college.

From these figures we see that for every litre of gasoline the car consumes, it needs 3402x the amount of uncompressed hydrogen gas to provide the same energy.

The first question is can we even fit this in the cylinder to be burned?

Fuel usage is 0.09 litres per minute, and RPM is 2700, so for every full revolution 0.0000333 litres of fuel is being used, or 0.000008325 litres every induction stroke (8.325 microlitres).

If we multiply that by 3402 to see how much hydrogen we need, we find that every induction stroke requires 0.02832165 litres of uncompress hydrogen gas, which is a lot. On a 1.8l engine the cylinder size would be 0.45 litres maximum, so at least so far at this engine speed and fuel usage it seems we are onto something. You can theoretically fit enough hydrogen into a cylinder on each induction stroke to replace fuel.

Assuming the same 14.7:1 ratio still applies, you have to add 0.416328255 litres of air to the cylinder to burn. This is only just possible, and the mixture may have to change anyway to use hydrogen in place of fuel, but this is something somebody with more knowledge than me can hopefully answer.

So lets assume for the moment that the engine can use hydrogen as a replacement for fuel, but only just and only when very low amounts of fuel were required anyway.

According to the interwebs, the autoignition temperature for hydrogen is 500 degrees C. The autoignition temperature for gasoline is 280 degrees C. This suggests it is not likely to ignite on it's own faster than gasoline does causing misfire, so here's another point for hydrogen. We know that it can be kept at extreme pressures too, so it's not likely to combust on its own there. It's looking good for the actual usability of hydrogen assuming the first two issues were not a problem.

I'll leave it to somebody else to cover how precisely you can deliver this much gas into the cylinder fast enough, as thats for someone with more experience/knowledge to comment on.

So lets go back to the first two points. If we assume that 3402 times as much hydrogen is used than gasoline each minute, that means we have to supply the engine with 0.409 litres per minute or 24.54 litres per hour however you prefer to look at it.

You can get hydrogen in these quantities, costing around $4 to $10 per kilogram depending upon how it is extracted, which at around 0.071kg/litre is a little over 345 litres.

So, lets assume the upper price tag and say hydrogen works out to be $0.0289 per litre, and around me (south-west england) regular gasoline is 1.42 or $2.287 per litre.

This makes hydrogen a whole 79x cheaper to buy than regular fuel per litre, making it appear brilliant! But when you consider that you require 3402x as much, hydrogen then becomes almost 43x more expensive than gasoline to run your car on.

So far we have found: Hydrogen can be used in an internal combustion engine in place of fuel, but only just, as you have to almost fill the entire cylinder with it when cruising along efficienctly just to be able use it at all when uncompressed. Using it compressed would be pointless as this means the engine has to work even harder on the compression stroke than usual, and would only be useful if lots more power was produced or it was a lot cheaper.

Not looking good so far. If you buy your hydrogen you pay anywhere between 20x and 43x as much for the same power output.

Now, the only possible way hydrogen could be useful whatsoever in an internal combustion engine is if you make it yourself, or buy it much much cheaper. If you are lucky enough to get your hands on huge quantities of hydrogen for a huge amount less than the normal asking price then great! Give it a go! You're still better off using it in a Hydrogen fuel cell car though as it would be much more efficient without all the usual frictional losses, and you'd be able to use it more successfully; as we discovered above it can only just about be used to sustain an engine by filling the entire cylinder.

You should be able to see by now that generating HHO by means of an alternator would be very difficult. You'd have to generate huge amounts of it by using almost no power at all, because adding any load onto the alternator would drop the efficiency rate straight down meaning the hydrogen could not sustain itself, so this is out of the question.

The only remaining possibility is to get the hydrogen by other means. You could generate it using power from a seperate battery, which is then recharged at home. You could also generate the hydrogen at home using mains power, renewable energy in the form of solar/wind/water, or naturally using algae or something similar.

If you can do this, the only question remaining is can you:

1) Produce enough to satisfy the car's requirements
2) Produce it cheaply enough to be justifiable
3) Store it and use it in a safe enough way
4) In the case of home energy usage, make it more practical than just using an electric car charged from home.

If you can somehow satisfy all these requirements, then I see no problem with giving it a try.

To sum up then:
  • You might be able to use hydrogen to run a car in theory
  • You cannot produce it using power from the alternator, or by adding any kind of significant load to the engine
  • It could be useful only if you can create it cheaply, and in sufficient quantities
  • There is absolutely no point if you end up spending more money, or using more electricity than it would take to simply run the car on electricity or gasoline in the first place
  • It is only useful if you can create the hydrogen yourself, as it is more expensive to buy than petrol
  • You would only be able to use it under certain conditions, and it could never replace fuel entirely

I doubt very much all my mathamatics here will have been perfect, so I'll leave it up to the experts to give their advice and opinions here.

I do hope that this will be of use or of interest, and sorry for making it so long, I just wanted to cover everything as it seems to crop up everywhere with no decent enough answers to prove it one way or the other.


Last edited by chrisoverson; 04-21-2012 at 02:12 PM..
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Old 04-21-2012, 02:20 PM   #42 (permalink)
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14:7 stoichiometric for gasoline engines is by mass, not volume. If going by volume, it is around 10000:1. Stoichiometric for hydrogen is 34.3:1 by mass, 2.39:1 by volume.

Making an engine run on hydrogen is relatively easy. It has been done many times. Running an engine on hydrogen produced by an alternator is mathematically impossible. Period. If it was possible, I would be installing windmills on my electric car as a range extender.
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Old 04-21-2012, 03:18 PM   #43 (permalink)
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So basically, it is wrong to instantly dismiss any thought of running a car on hydrogen or HHO as people do, but you simply cannot do it in the way that many people attempt.

If you can aquire the hydrogen cheaply enough, produce it by other means at home, or recharge a battery at home then use it to generate hydrogen whilst driving then it is actually possible to make gains with it. It's just a question of whether you gain more than you lose .

I've wondered about making a windmill that rises up out of the sunroof while the car is parked xD. Not sure where it would go inside the car though... fold up inside the roof maybe? :L
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Old 04-21-2012, 03:25 PM   #44 (permalink)
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Chasing windmills, how apt.

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Old 04-21-2012, 04:08 PM   #45 (permalink)
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I think I'll come up with an engine that runs off of the gas produced by Alka-Seltzer tablets.
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Old 04-21-2012, 05:51 PM   #46 (permalink)
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Originally Posted by Frank Lee View Post
Chasing windmills, how apt.
...Hypermiling Engineering by Don Quixote.
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Old 04-23-2012, 03:08 AM   #47 (permalink)
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no dyno needed

Just snip the fuel line in two and install a flow gauge in there. If hydrogen works, it should show up as slightly less fuel needed to push the engine against a brake dyno held at a certain speed.

which flow gauge? they aint cheap and usually they require a black box to supply you with meaningfull data, analog ones need to be installed in place to get real time readout...

I've talked to many hydrogen proponents, and the only ones who have any halfway sensible numbers to show are those using aftermarket engine management to "tweak" the engine to "optimize" running on hydrogen. The challenge is to show that the engine can't work at the "tweaked" settings without hydrogen boost, and that the fuel savings aren't simply due to running the engine leaner... which can be done in most cases on typically conservative factory fuel maps.

this would be the scenario in an indirectly injected diesel (mechanical injection pump) one fitted with turbo is even better. with humongous amounts of surplus air the addition of another fuel is easy to detect. diesels respond well to gasseous fuels standalone, or, in addition to #1 or #2 diesel. trickle a bit of flammable gas into the intake air tract and you will have additional power which will give you a lower throttle setting and or lower RPM. doesn't get any simpler. in case of HHO, preheating is very likely a requirement. it could be heated even more by introducing the gas pre turbo and although not likely, safety concerns might arise from doing so. perfect if the system lacks an intercooler. if the HHO is stored cryogenically it will require enormous preheating which could produce some challenges. onboard generation by deriving power from the main (propulsion) engine - even if just to supplement will not produce a smile from a fuel saving standpoint. i know a guy who did both HHO and propane supplementation in an 80's turbodiesel mercedes. will pick his brain...

All the doubletalk in the world can't cover up the fact that there is no dyno evidence and no scientific evidence for "HHO". On the other hand, there's plenty of evidence for meth-injection and water-injection (though water-injection benefits in terms of economy aren't really that big), which don't rely on hocus pocus to work.

water injection in gassers does all sorts of wonderful things:
allowing the use of poor gas, a bump in timing, more controlled burn, ability to lean AF ratio, delay/prevention of pre-ignition, valve cleaning, ring and c-chamber decoking... i have often mused what it would do for extreme lean burn. if i were to ever buy a honda it would be an HF!

I've got a dyno I can borrow, as well as AFR sensors and an OBD reader that can be hooked up for dyno-sessions. And I've got a car equipped with a stable aftermarket EMS for a test bed.

Every time I hear one of these outlandish claims locally (HHO, fuel line magnets, magic fuel additives), I tell them: Pay me for the dyno-time, and we'll test it. If your numbers work out, then I'll publish the results.

i would do it but it's a long drive

So far, no takers. Big surprise. Well... some of the additives do work, a little... but not as effectively as simply buying higher octane gas...

soltron can cure smoke in diesels but i have never used it in gassers.
which additives have you known to work? the few fuel injector cleaner additives that actually work - simply do so by allowing the injectors to work as intended. no magic in the bottle needed.
here in the USA some high end gasolines claim to have injector cleaners built in...
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Old 04-23-2012, 04:34 AM   #48 (permalink)
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The ones that do work simply do so by bumping octane. Our local fuel is, by government mandate, E10. Many E10 blends locally have terrible RON. Many of the local cars are Korean or Japanese, and are optimized for 95 RON fuel and suffer when loaded with 92 RON with E10. Knock is not an uncommon problem over here.

Fuel savers that bump RON by that much tend to show up on the dyno and actually show a little improvement in efficiency on cars that typically gain efficiency with 95 RON, anyway.
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Old 04-26-2012, 04:22 AM   #49 (permalink)
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quickly found 2 sources...

thisone: http://nanohub.org/resources/6570/do...12-Woodall.pdf
*suggests* a 15% HHO enrichment gains 30% in economy on diesel engine.
they are also working on a low cost catalyst (vs platinum) for electrolyzing the HHO. from Purdue university

and running a plantoil as a diesel substitute this study suggests success as well:

niky: in your area you should have no difficulty finding someone with an experimentative nature with some kind of japanese IDI diesel (up to late 80s) - to prove your concept!

Last edited by max_frontal_area; 04-26-2012 at 04:23 AM.. Reason: ooopsed
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Old 04-26-2012, 08:21 PM   #50 (permalink)
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Those results have been discussed elsewhere on this board in this context. Two very important points about them:

1 - It's diesel, most "HHO" discussions are about gasoline-powered cars.
2 - The quantities of hydrogen used in that experiment are a couple of orders of magnitude higher than come out of these on-board hydrogen generators.

So if you can get a whole lot of hydrogen for free, compress it for just about free, and store it on board your diesel car, you can get better economy until your bottle runs out. But that is a very far cry indeed from using the car's engine to generate hydrogen and then burning that in with the gasoline powering your spark-ignition engine.


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