Plug-in hybrid using hydrogen injection

[JapaneseJeep]

Originally Posted by freebeard

Would you capture both gases or just the Hydrogen, and rely on ambient air for combustion?

One could feed the Hydrogen, store the Oxygen, and use it for a booster like NO2 ....or use it to rouse a sleepy driver.

Ideally, I would use an existing water-welder system (i.e. HHO, both H2 and O2) with as few modifications as possible except running it off a separate battery. I know there are ways of electrolytically obtaining pure H2, but those introduce unwanted complexity. My objective here is to make something 100% off-the-shelf and as cheap as possible.

Another fear with pure H2 separation is that, particularly in the mountainous regions that I frequent, the engine would be flooded with hydrogen and starved for oxygen. Not so when the car is making both on its own.

However, this being completely hypothetical at the moment, I'm open to any disagreements or alternative hydrogen-related ideas you can throw at me.

[Ecky]

Originally Posted by JapaneseJeep

This last paragraph captures exactly the spirit of what I'm after. Is it going to be the best option? Absolutely not. Is it going to be a little silly and of questionable commercial value? Sure... but what I want is to know whether or not it will make a significant MPG increase, all other factors be damned.

Now the question is how well this will actually translate when I simply don't have access to the equipment or know-how needed to safely and efficiently bottle my generated hydrogen/HHO.

Botting high pressure hydrogen is dangerous and expensive, but assuming you can do it, the gains would be proportional to how much hydrogen you can carry/inject. Most HHO systems amount to a tiny fraction of a percent.

Engineering Explained released a video on hydrogen combustion just a few days ago. IIRC, the conclusion he came to was that, for a very efficient V8, a 60L tank (think large street-side trash bin) filled to 5000PSI with hydrogen would be good for around 60 miles of hydrogen-only range. If you're going half and half with gasoline, you could double your fuel economy for the first 120 miles with a tank just about the size of the rear passenger compartment in most sedans.

With a much more efficient engine, say a Geo Metro 3 cylinder, you could get the same doubling of economy for around 500 miles per hydrogen fill.

[JapaneseJeep]

Originally Posted by Ecky

Botting high pressure hydrogen is dangerous and expensive, but assuming you can do it, the gains would be proportional to how much hydrogen you can carry/inject. Most HHO systems amount to a tiny fraction of a percent.

Engineering Explained released a video on hydrogen combustion just a few days ago. IIRC, the conclusion he came to was that, for a very efficient V8, a 60L tank (think large street-side trash bin) filled to 5000PSI with hydrogen would be good for around 60 miles of hydrogen-only range. If you're going half and half with gasoline, you could double your fuel economy for the first 120 miles with a tank just about the size of the rear passenger compartment in most sedans.

With a much more efficient engine, say a Geo Metro 3 cylinder, you could get the same doubling of economy for around 500 miles per hydrogen fill.

Obviously the dynamics are a little different when you're working with pressurized gas, but overall, this is what makes me believe that on-the-fly HHO/H2 generation would be the way to go. Both of the engines that I have available for this project (Subaru FB25 and Honda D16) are relatively efficient four-cylinder designs, the Honda especially so. Further, the gain I'm looking for is nowhere near double efficiency... I'd be satisfied with a 5-10% increase since I'm getting the electricity and water for free.

I'll have a look at that video, thank you very much for the pointer.

[Ecky]

Originally Posted by JapaneseJeep

Obviously the dynamics are a little different when you're working with pressurized gas, but overall, this is what makes me believe that on-the-fly HHO/H2 generation would be the way to go. Both of the engines that I have available for this project (Subaru FB25 and Honda D16) are relatively efficient four-cylinder designs, the Honda especially so. Further, the gain I'm looking for is nowhere near double efficiency... I'd be satisfied with a 5-10% increase since I'm getting the electricity and water for free.

I'll have a look at that video, thank you very much for the pointer.

The issue with on-the-fly generation is this: Let's say you have a 100w HHO generator. At 20% cracking to combustion efficiency, you're looking at getting 20w of hydrogen out of it. If you're cruising on the highway using 20hp, that works out to around 15000w of energy from gasoline to the wheels. A 100w HHO generator run off a battery thusly should cut around 0.1% fuel consumption. Increase it to 1000w and you're getting 1%.

[JapaneseJeep]

Originally Posted by Ecky

The issue with on-the-fly generation is this: Let's say you have a 100w HHO generator. At 20% cracking to combustion efficiency, you're looking at getting 20w of hydrogen out of it. If you're cruising on the highway using 20hp, that works out to around 15000w of energy from gasoline to the wheels. A 100w HHO generator run off a battery thusly should cut around 0.1% fuel consumption. Increase it to 1000w and you're getting 1%.

This all seems solid, but still leaves the question of how the studies I mentioned came to their conclusions using similar methods. Particularly in the first paper, where the HHO generator was of an (albeit optimized to the particular engine) dry-cell plate design and managed to reduce fuel consumption by 34% while connected to the alternator.

Alas, I don't think this will be settled without experimentation.

[oil pan 4]

If they really increased fuel economy by a third then everyone would be using them.

[Ecky]

Originally Posted by JapaneseJeep

This all seems solid, but still leaves the question of how the studies I mentioned came to their conclusions using similar methods. Particularly in the first paper, where the HHO generator was of an (albeit optimized to the particular engine) dry-cell plate design and managed to reduce fuel consumption by 34% while connected to the alternator.

Alas, I don't think this will be settled without experimentation.

Broadly speaking, every HHO study I've found hasn't actually stood up to rigorous scientific scrutiny. They're generally snake oil.

There are some small benefits, such as hydrogen burning faster than gasoline and allowing slightly less advanced ignition timing, and the extra knock resistance, but from a total system energy perspective they produce 1/5 the energy they consume.

[Logic]

I get you:
If you have a normal ICE car and you want to turn it into a plug in hybrid; efficiency aside, this is probably the easiest way:

You don't need to get the power from an electric motor to the wheels and you don't need to integrate a motor controller with the accelerator and brakes.

Some regen is possible if you have a cutoff valve/solenoid activated by the brakes or a vacuum sensor and a ...'balloon'/reservoir after that in the hydrogen feed line and gear down while slowing.


Efficiency ideas:

The RC aeroplane industry has some very efficient motors that can be modded into alternators. (95+% IIRC)

Electrolyzers are more efficient when a properly set up magnetic field within the cell/s is involved.
There is research proving this and some vids on YouTube.

Pulsed power at certain frequencies also seems to help. Possibly because the pulses set up a magnetic field..?

If you use pulsed DC; use pulsed ~2.1 Volts in a parallel cell;
An open cell is way easier to keep full vs a closed (efficient) series cell, without the efficiency loss.

The exhaust O2 sensors look like they need some fooling or they pick up on excess O2 and the injection system adds fuel..?
In fact you want to run slightly lean and let the HHO 'fix' the arising burn issues.
or
Retard ignition timing slightly, thx to a faster burn..?

Add the HHO after the airflow meter so the system does not add fuel to what is essentially the ideal O to H/fuel ratio already.

According to the science; the most efficient voltage across the HHO cell/s is 1.61 Volts IIRC.
But a voltage of just over 2.1 Volts means some of the O is turned into Ozone (O3) which is good. Both volumetrically and according to a # of studies.
That's probably why tests seem to favour 6 cell (in series) electrolyzers over 7..? (2.2 V per cell vs 1.8)

Engine coolant can be used to quickly heat the HHO cell to a more efficient temperature and then keep it there/cool it.

Using a good old radiator cap on the 'above idea cell' will slightly pressurise it, avoiding any tendency for the electrolyte to boil while at the above more efficient, higher temperature.
That's akin to using a tiny bit waste heat to help produce the HHO.

[oil pan 4]

Over thr years we have had several people say "I'll get one to work and show you how" and we never hear back from them. I like to think they died in an hho explosion.

[aerohead]

I'd request a complete mathematical representation of the complete energy balance for every stage of the process, beginning to end, illustrating an overall net benefit.
Science is mathematics.
Without quanta we have nothing.