I would suggest the use of "fuel" rods or even a reel of wire. The material needs to be preheated as well as the reacting solution prior to hydrogen generation but there after it is self sustaining. Regarding the temperature of combustion in an internal combustion engine, hydrogen burns with an intense localized heat with very little radiation. It is this that causes problems. People have tried injecting water along with the hydrogen to lower the reaction temperature with some success. Note that in terms of work over time this then also slows the expansion rate and the piston expands with relatively constant force over the power cycle (steam engine). Constant force or nearly so over the power cycle , is preferable to a sudden shock pressure and then a dramatic fall off. This is what gave steam cars a great torque advantage compared to internal combustion engined cars. Also, they ran very smoothly when at this time gasoline engines were rough beasts. Do not forget that such engines commonly were double acting and had a power and exhaust stroke not 1 power stroke in 4. They can be made very compactly for the power output. It is the flash boiler and exchangers that take the room up. Modern flash boilers are virtually instantaneously ready and have a very high efficiency. Regarding the carnot efficiency, there is nothing to stop external combustion engines running at high carnot efficiency compared to internal combustion engines. The steam pressure and temperature simply have to be high and the exhaust at relatively low temperature. This requires efficient flash boilers and heat exchangers. Such situations are common in power stations where the steam turbine to electric energy output can reach 60%. Cheers Barry On 6/8/07, Manfredi, Albert E <albert.e.manfredi@xxxxxxxxxx> wrote:
Barry Wilkins wrote: > As Aluminium has a similar energy to weight ratio as petrol > when oxidized (burnt) it would appear to be a very stable > and practical alternative to fossil fuel. > > Of course the original energy is derived from the > electrolysis of aluminium oxide to the metal and this > process has its losses and requires electrical energy which > may perhaps be derived from an original fossil source. Interesting. Sort of similar to the H2 proposal, where the aluminum, like the hydrogen, is only used as a means to transfer energy. Both start and end in their original state (aluminum oxide in this case, or water in the case of H2 fuels), and the problem becomes one of purifying the stuff efficiently, and then transporting it to the consumer efficiently. How would you deliver and then load this purified aluminum into vehicles? Pellets? > Problem is, you have already lost some energy in the > splitting process and internal combustion engines run on > hydrogen run so hot that valves and pistons are destroyed. > So for these reasons an external combustion process (which > is cleaner burning) and makes use of the heat of reaction > would be preferred. The electric cell/motors are required > for instant demand as a turbine has a slow acceleration > rate and should be operated at optimum revs continually. As long as you're going to do external combustion, my preference is also electric motors. They are clever and simple, as opposed to rube goldberg contraptions like engines. However, one of the really cool things about internal combustion engines is that they can operate at a much higher temperature, therefore higher Carnot efficiency, than external combustion engines. Because there is no barrier that has to survive the high temperatures. In a piston engine, the peak temperatures at top dead center are much higher than the metal could survive, and the only reason it works is that the piston quickly moves down, expands the volume, and therefore cools the mixture. Somehow, I don't see that basic advantage to be easy to beat. What you have to do here is bank on some sort of renewable energy or really cheap energy source, in the purifying process. Bert ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.