CPL.Luke Posted November 25, 2006 Share Posted November 25, 2006 alright so hydrogen cars seem like a good idea until you think about how explosive hydrogen is, what happens when there's an accident? and if the car did explode in a place like NYC or in a traffic jam, what woud happen to the other cars in the area? could you have a giant chain reaction? Link to comment Share on other sites More sharing options...
insane_alien Posted November 26, 2006 Share Posted November 26, 2006 nah, its not as explosive as people think. It probably won't even be stored in is hydrogen form. The current most likely solution is metal hydrides which, if exposed during a crash would slowly react with moisture in the air and give off hydrogen slowly. not explosively. if it rains the hydrogen will be given off a bit faster but still not explosively. a hydrogen fire like this would be a lot less dangerous than a petrol fire since hydrogen rises quickly while petrol seeps down and pools around where there might be injured people unable to escape the fire. Link to comment Share on other sites More sharing options...
Rocket Man Posted November 26, 2006 Share Posted November 26, 2006 the hindenburg blew up because of aluminium based paint, very flamable. the hydrogen makes a lot of heat but the explosion is fairly localised. if they stored the hydrogen as compressed gas, the main issue would arise from explosive decompression not combustion, lpg cars i think are more dangerous because the combustion of the fuel leads to an increased volume of gas - hydrogen combustion actually reduces the number of moles of gas and condenses pretty quickly. Link to comment Share on other sites More sharing options...
CPL.Luke Posted November 28, 2006 Author Share Posted November 28, 2006 I know from personal experience that if hydrogen is mixed in with the air in the proper ratio it is highly explosive. Also I had a friend at the university of Iowa, they got hold of a 5 liter water jug, filled it with hydrogen and blew it up in the middle of the road. it apparently made a decent sized pot hole. Link to comment Share on other sites More sharing options...
insane_alien Posted November 28, 2006 Share Posted November 28, 2006 well, the hydrogen isn't likely to be under so much pressure as the most effective ways of storing it ar when its chemically bonded to something. also its not going to be mixed with oxygen till it hits the fuel cell. Link to comment Share on other sites More sharing options...
Corillian Posted December 1, 2006 Share Posted December 1, 2006 My friend won't listen to me, please tell me the volativity and explosive(ness) of hydrogen is Link to comment Share on other sites More sharing options...
insane_alien Posted December 1, 2006 Share Posted December 1, 2006 its only explosive when mixed with an oxidiser and it is a gas so volatility doesn't really apply Link to comment Share on other sites More sharing options...
Corillian Posted December 1, 2006 Share Posted December 1, 2006 Is it reallym really explosive in oxides, like absolutely explosive, in oxides Link to comment Share on other sites More sharing options...
insane_alien Posted December 1, 2006 Share Posted December 1, 2006 what? i really don't understand your question. can you explain it a bit more. what i was saying is that hydrogen is only explosive when it is mixed with an oxidiser (lets use oxygen for simplicity but it applies to others as well) so a mixture of 2:1 H2:O2 would be explosive. but a mixture of 200:1 H2:O2 well, you probably couldn't even get that to burn. so, if you have a bag of pure hydrogen and you light it on fire, it will only be a narrow band around the boundary of the hydrogen that will be burning. inside you will have pure hydrogen and outside you will have the oxygen in the air. the bit that burns is where enough oxygen has mixed to allow it to burn. Link to comment Share on other sites More sharing options...
Rocket Man Posted December 14, 2006 Share Posted December 14, 2006 I know from personal experience that if hydrogen is mixed in with the air in the proper ratio it is highly explosive. Also I had a friend at the university of Iowa, they got hold of a 5 liter water jug, filled it with hydrogen and blew it up in the middle of the road. it apparently made a decent sized pot hole. nice! hydrogen makes a decent acoustic, focussed slightly by the jug would make a hole in almost anyhting at point blanc. the main thing to consider in this case is that hydrogen explodes differently to any other flamable gas, the initail shockwave is very powerful but does not fill the area with more moles of gas than previous to combustion. petrol explosions make huge amounts of gas so the pressure lingers even after the gas has cooled via radiation, hydrogen dissapates it's heat fairly quickly and and the pressure remains roughly constant instead of throwing large objects around. i still think that the pneumatic explosion from the cylinder is more dangerous than hydrogen combustion Link to comment Share on other sites More sharing options...
K@meleon Posted January 4, 2007 Share Posted January 4, 2007 I think the explanation of Rocketman is quite right. I heard from many people working with the stuff that they didn't really consider hydrogen to be explosive, but more highly flamable. It is like the news reports during the Challenger accident with some reporters claming they heard a big explosion. But the truth is that there was no explosion. It consummed. The boosters were still intact for instance. To come back to the car problem, engineers are considering different alternatives to store hydrogen. I had a lecture by people believing that the most practical way of storage was pressurized hydrogen at 700 bar. They had interesting video footages comparing what would happen if the hydrogen tank and a petrol tank caught fire. The hydrogen tank had a fire plume reaching a few meters upwards, which last a few seconds, without damage to the car. In contrast, the conventional car exploded within two minutes.. It seemed quite convincing to me... Link to comment Share on other sites More sharing options...
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