http://www.iht.com/articles/ap/2007/...apan-Mazda.php

I've been looking at the problem of ICE warm-up when it hit me that hydrogen makes a lot of sense during warm-up. The excellent combustion characteristics of hydrogen is exactly what the engine needs in the first five minutes.

Hydrogen has a wide combustion range ratio so evaporation temperature becomes a mute point. It would also eliminate any hydrocarbon by-products during warm-up. Furthermore, not much would be needed during the warm-up so home generation would be practical. (LATE THOUGHT: hydrogen burns to make water and that might short the sparkplugs in extremely cold weather during the first start. To some extent, CO(2) avoids combustion chamber condensation.)

An acceptable substitute would be methane, again readily available in natural gas homes. We don't need it for the whole trip, just long enough to get through warm-up. The only challenge with methane are silicones but if used just for warm-up, they may not be a significant problem. Then the ICE can switch to ordinary gas or liquid hydrocarbon fuels.

Bob Wilson

 

I'm no expert on ICE's but you'd think the heat released would keep the water in vapor form until she makes it to the exaust wouldn't it? I mean all "fuels" produce significant water vapor when burned don't they?

I've always hesitated calling hydrogen a "fuel". Its more of an energy storage medium. Unless someone finds a way to tap vast resources of hydrogen (a fuel line to Jupiter anyone) it has to be PRODUCED using energy, by burning real fuels, or other energy sources. In the end converting energy by burning fuels and creating hydrogen could be less polluting than gasoline, but I'm kind of annoyed when the media oversimplifies it and makes it sound like if you just switch to hydrogen all your problems are solved.

 

The problem is the intermittent combustion. The first 'firing' provides some heat but the cylinder head and spark plugs are going to mostly be at ambient temperatures until enough occur to transfer heat below the surface. During this time, especially after the exhaust valve opens and the pressure and temperature plummet, that condensation and even ice can form:

http://www.sacskyranch.com/eng182.htm

Now has the ratio of carbon to hydrogen goes up, the resulting C0(2) and CO tends to dilute but not eliminate the risk. But burning pure H(2) sounds like an invitation to more spark plug icing.

As for using H(2) as a fuel, extreme rockets, maybe, but liquid CH(4) has excellent characteristics and compared to liquid H(2), a much better solution. Perfect is the enemy of 'good enough' and in this case, CH(4) makes a lot of sense.

A little known fact is the X-15 rocket plane used NH(3), that boils at -33C versus -161C of methane. I've long thought ammonia would be a better hydrogen transport mechanism than methane for a fuel cell because it decomposes into a very pure H(2) and N(2). Due to the formation of nitrogen oxides, ammonia is a poor engine fuel.

Bob Wilson