13 replies to this topic

[malbear]

came across this video about the efforts at JCB

 

https://www.youtube....h?v=19Q7nAYjAJY

 

 

[gruntguru]

Boeing claims breakthrough in ultra-lightweight all-composite cryogenic fuel tank construction.

 

https://www.designfa...rearticle&pn=02

 

Significant advance for space travel with future implications for commercial aviation (and FCEVs?)

[Ben1445]

I can see a pretty clear path for that to bleed into commercial aviation and there's absolutely a pretty high level of interest right now in developing composite cryogenic tanks for future airliners already. 

 

In relation to this specific development constituting an advance for FCEVs... I'm not so sure. You get really quite a good workable range out of fairly small, composite compressed hydrogen tanks already that it's hard to see any particular benefit of shifting to cryogenic hydrogen fuel. It would be a lot of added hassle to produce and handle at the extremely low temperatures as well as giving rise to difficulties in storing it in the vehicle for long periods of time. There may be a few edge cases but for most vehicles in regular use on public roads I don't see it as a practical solution. 

[desmo]

Boeing claims breakthrough in ultra-lightweight all-composite cryogenic fuel tank construction.

 

https://www.designfa...rearticle&pn=02

 

Significant advance for space travel with future implications for commercial aviation (and FCEVs?)

Reading that got me almost no closer to knowing what the innovation actually is.

 

H2 is potentially a great fuel, be nice if there were a practical source and infrastructure for it.

[gruntguru]

Reading between the lines, they are building up the vessel walls with thin laminates so the resin is discontinuous as you progess through the wall section. I can imagine this would allow greater flexibility as the vessel undergoes the extreme thermal cycling that causes cracking when composite materials are used for cryogenic storage.

Edited by gruntguru, 28 February 2022 - 02:11.

[mariner]

From the ever productive Enginelabs site 

 

https://www.enginela...bustion-engine/

[desmo]

Is there any reason converting an ICE to H2 would be much more difficult than converting one from petrol to LNG or propane? I think that's pretty straightforward, to the extent that even a small shop or hobbyist can manage it.

[Greg Locock]

The main  difficulty is on the fuel handling side, not the engine itself, once you have an air fuel mixture. Of course there are probably issues with hydrogen embrittlement and so on. It would be a very expensive way to run an engine.

[malbear]

The main  difficulty is on the fuel handling side, not the engine itself, once you have an air fuel mixture. Of course there are probably issues with hydrogen embrittlement and so on. It would be a very expensive way to run an engine.

what would be the most effected site for embrittlement. the steel or aluminium . the steel valve stems or inserts or top ring. could the ring break in time or valve head drop off presumably the exhaust one because of heat.?

[Greg Locock]

Well that's funny. We called any hydrogen effect hydrogen embrittlement, turns out there are two different mechanisms. HighTempHydrogenAttack is going to be present in the combustion chamber and exhaust valve, where the hydrogen gas bonds with the carbon in the steel, turning it into wrought iron and methane, and EXPLODES the grain boundaries, causing cracks. Harry Watson at RMIT (I think) had many projects injecting H2 into an engine to initiate or modify the combustion, a friend of mine was one of his student researchers.

[malbear]

I read somewhere that hydrogen burns into quench zones much smaller crevices than petrol will burn . would an engine without valves Ie two stroke have a advantage reducing critical embrittlement ?

[Greg Locock]

Seems possible, but I think using H2 as a fuel in an IC engine is such a daft idea that i wouldn't waste any time on it. If you are making it out of natural gas, use the gas, and if you are making it by electrolysis then fuel cells/ammonia/resynthesizing methane all seem like a better use.

[Zoe]

I know from liquid fuel rocket engines that material selection has to take into account hydrogen embrittlement. But then it is mostly at cryogenic temperatures.

[cbo]

Audi rejects synthetic fuels and Hydrogen for road cars.

https://www.topgear....SPmWrvpSjMoixQ4

Edited by cbo, 21 March 2022 - 19:44.