Hydrogen for LPG fantasy?

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slickwix
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Hydrogen for LPG fantasy?

#1 Post by slickwix » Thu Jun 04, 2020 8:12 pm

Here's a question that's been floating in my head for a while regarding hydrogen.
Now I've searched already on the forum and seen some threads already made regarding this topic.....but here's my angle.
Where I live (Norway), they are talking of phasing out fossil fuelled vehicles in the next 10-15 years. Unfortunately LPG is classed as fossil (fair enough).
Hydrogen gets all the perks over here - free tolls, free parking etc, and it looks like it is one of the fuels the government want us to be using in the foreseeable future.
So, my fantasy question, is it ever going to happen that a "relatively simple" tweak to an LPG combustion system will be created to turn an LPG into a hydrogen run vehicle?
I'm no engineer or mechanic, but the dynamics seem the similar. Perhaps there already is such a fix in existence or in the works already???
Just daydreaming about the future.
Slick

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Re: Hydrogen for LPG fantasy?

#2 Post by LPGC » Thu Jun 04, 2020 8:48 pm

Some of the dynamics are very similar but the injectors would need to be comparatively high flowing to account for the stochiometric ratio of hydrogen.

The ECU and sensors would work fine.

With one major proviso - hydrogen attacks a lot of materials including steel etc, so components including above mentioned injectors, sensors and also reducers would need to be rated for use with hydrogen, as would the fuel tank and fuel lines. Some of these points in most cases won't be an issue at all, some points will mean certain injectors and certain system pressure sensors would have to be avoided. I haven't seen a hydrogen rated reducer for sale yet.

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bigbadwolf
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Re: Hydrogen for LPG fantasy?

#3 Post by bigbadwolf » Fri Oct 16, 2020 10:44 pm

someone needs to come up with this fantacy fix as Shell UK have just pulled LPG of 59 of their forecourts.

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Re: Hydrogen for LPG fantasy?

#4 Post by Gilbertd » Fri Oct 16, 2020 11:50 pm

So if I can find a suitable vaporiser, I could convert my singlepoint? It runs very nicely on the 50/50 Propane/Butane mix sold in some European countries, in fact, it's more economical on it.
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Re: Hydrogen for LPG fantasy?

#5 Post by Gilbertd » Fri Oct 16, 2020 11:57 pm

Just for the hell of it I've just looked it up. Stoichiometric ratio is 34:1 by weight and, as Hydrogen is pretty light, that's an awful lot in terms of volume. However, it has an Octane rating in excess of 130 RON, so while you'd need a pretty big tank to carry sufficient for a decent range but you could raise the compression ratio of the engine almost to diesel levels and give it so much ignition advance you could get through a tankful at a frightening rate! This is definitely one that needs to on Robertxx's list of things to play with......
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


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Re: Hydrogen for LPG fantasy?

#6 Post by Brian_H » Sat Oct 17, 2020 8:59 am

bigbadwolf wrote:
Fri Oct 16, 2020 10:44 pm
someone needs to come up with this fantacy fix as Shell UK have just pulled LPG of 59 of their forecourts.
Its actually 212 they have pulled if you count all the ones listed by Autogas. The list posted on https://autogaslimited.co.uk/ only contained the last few ones they removed or plan to remove.

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Re: Hydrogen for LPG fantasy?

#7 Post by Pinger » Mon Oct 19, 2020 12:26 pm

I remember reading a long time ago that hydrogen was prone to pre-ignition. Of course, pre-ignition and detonation are not the same.
This tendency toward pre-ignition (if true) is at odds with its auto ignition temp of 585C (substantially above petrol's (280C) and propane's (470C) at first sight. But the auto ignition temp of methanol is 470C and it is known to be pre-ignition prone (hence it's use in glowplug fuel for model's engines) but also detonation resistant. Methanol though has the intrinsic ability to cool - thus reducing any hotspots within the cylinder that may give rise to pre-ignition (a glowplug has platinum and ignites partly due to a catalytic reaction). Gaseous hydrogen will not have that advantage - and wouldn't be present in the copious quantity that methanol would be.

There's some discussion here >> https://forums.mbclub.co.uk/threads/ele ... re.267110/ beginning at post #12 about hydrogen's role as a motor fuel - including a (short) Hyundai video where a hydrogen fuel cell is proposed as a charger (not fixed to the vehicle) for the battery of an EV. Presumably in a commercial context (as it isn't clear how hydrogen would be delivered for a home sited unit) with the intention of its hydrogen being developed 'cleanly' from renewable electrical generation (or a surplus from other generating capacity). Thus, hydrogen's future appears to be as an energy store using electricity to make it then converting it back to electricity in a stationary fuel cell when electricity is required. When that requirement is a vehicle the obvious next step is the vehicle carrying the fuel cell and supplying the electricity directly to its traction motors. A home sited unit could generate hydrogen from wind and solar for that purpose - which I think was a Honda proposal that appears to have fallen off the radar.

Whatever role hydrogen may play, I think (though I could be wrong) that it is incredibly leak prone - something to do with having very small molecules (does a hydrogen filled balloon not deflate much sooner than an air filled one?). Or am I confusing it with helium?
And, its very very broad flammability limits make it a real explosive hazard. It is explosive in air in concentrations of 4 to 74%.

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Re: Hydrogen for LPG fantasy?

#8 Post by Brian_H » Mon Oct 19, 2020 7:55 pm

Helium has larger molecules than hydrogen, the two of them occupy the first two spaces on the periodic table. Leakage would be an issue as you say above, the Hindenburg being the best example of the issue with storage of hydrogen on anything thats mobile. Smaller molecules will leak through a smaller gap, so your ballon example would seem to be correct to me, I think both will leak quicker than an air filled ballon, though obviously helium isn't flammable.

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Re: Hydrogen for LPG fantasy?

#9 Post by LPGC » Mon Oct 19, 2020 9:30 pm

Apparently hydrogen can cause problem for metals such as metal injector bodies and more importantly such as metal tanks, it can (forgive the term if it's wrong because I'm not a chemist) 'hydrogenise' such materials (change the chemical structure) turning them brittle. Probably not much chance of anything similar with helium but being an inert gas helium wouldn't be much use as a fuel either lol (and incidentally / another apparently - helium is supposedly getting scarce these days).

While a vehicle running on LPG performs very similarly to a vehicle running on petrol, a vehicle running on hydrogen will make much less power than the same running on petrol or LPG. Perhaps to the extent that a lot of vehicles would have problems idling running on hydrogen because the idle air valve wouldn't open enough to allow enough air for high enough idle speed, and/or problems with ignition timing and/or ECUs seeing errors due to far less torque than expected for a given airflow (including gearbox ECUs).

While it's very simple to split hydrogen and oxygen from water using electricity (ask me about ruining my bedroom as a kid lol) the 2 elements then have to be separated if it's only the hydrogen that's wanted to store in a tank and it's very energy intensive to split them and a bit wasteful because some energy will be lost heating the water.
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Pinger
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Re: Hydrogen for LPG fantasy?

#10 Post by Pinger » Tue Oct 20, 2020 9:37 am

LPGC wrote:
Mon Oct 19, 2020 9:30 pm
While it's very simple to split hydrogen and oxygen from water using electricity (ask me about ruining my bedroom as a kid lol) the 2 elements then have to be separated if it's only the hydrogen that's wanted to store in a tank and it's very energy intensive to split them and a bit wasteful because some energy will be lost heating the water.
Good point about then having to separate the hydrogen from the oxygen. In chemistry class we omitted that step and just burned the two with that 'pop'.

Hydrogen is a fantasy for some though. Maybe it's the difficulties of actual electrification (which is at least being attempted) that makes their dream preferable to reality.

edit PS. That last line isn't aimed at the OP. More those who rubbish all electrification (it has its place in the mix IMO) while suggesting hydrogen as the future when electrification has had considerably more development already but still isn't entirely viable or credible.

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