The problem with making hydrogen using electrolysis is that it uses more energy than you get from burning the hydrogen as fuel (laws of thermodynamics) Therefore, if you hook up an electrolyser to your car you would be drawing more energy from the engine than you would be gaining by burning the hydrogen. If you used a turbo alternator to generate the electric current needed, you would again be putting extra load on the engine due to back pressure etc, However, the exhaust on a car generates a lot of heat that goes to waste, what if you could make use of that heat. Some time ago, I saw a small steam generator at a Japanese techno fair, this was a closed loop system that only required a moderate heat source to work and could generate quite a bit of power depending on the heat put into it and it also stated up very quickly. If this generator could use the heat from the exhaust without interfering with the flow of gasses from the engine, you could use it to power an electrolyser to produce Browns gas which could then be burnt in the engine to supplement the existing fuel without putting extra load on the engine and thereby increase fuel economy.-- riggers100, Dec 11 2007 (?) BMW Turbosteamer http://en.wikipedia.org/wiki/Turbosteameralready 1/2 baked [afinehowdoyoudo, Dec 11 2007] call me a dummie or whatever else you like, I'm not ruling this out. http://en.wikipedia...iki/Water_fuel_cell [zeno, Dec 12 2007] Using a thermopile around the exhaust is not a bad idea ... apart from the fact it would condense a lot of water; but this could be collected and fed into the electrolyser.
It would be only marginally efficent, but it would recover some "waste" energy without violating any of the laws of thermodynamics..... [+]-- 8th of 7, Dec 11 2007 Well there are already hyrdrogen enriched engines, I'm not sure if they use waste heat.
The only thing I don't like is that it obviously less efficient to create hydrogen with the generated electricity than to use it for, say, a hybrid system.-- acurafan07, Dec 11 2007 No disrespect to your idea, [riggers100], but I think it would come over better with some paragraph breaks.-- pertinax, Dec 11 2007 Half-baked, to some extent - doing some research last year I came upon a commercial outfit that will put a series of peltier units onto an 18-wheeler's exhaust stack...-- FlyingToaster, Dec 11 2007 ok so I can't spell very well, thats why i trusted a spell checker, guess i should have checked what it was changing..... anyway, the point is that engines waste a lot of heat, there must be some way of making use of it instead of just letting it escape.
there may be a way of using both the radiator and the exhaust to collect energy?-- riggers100, Dec 11 2007 4whom813377 anno'ed here first!-- 4whom, Dec 11 2007 Anything that puts any of that waste heat to use, regardless of the efficiency, gets a bun from me.
My fantasy car has the radiator and exhaust system bristling with Seebeck devices.-- elhigh, Dec 11 2007 Most seem to have misread the OP, which refers to a steam generator, not peltier thermoelectrics. I bun the former, bone the latter..-- afinehowdoyoudo, Dec 11 2007 // steam generator, not peltier thermoelectrics //
Not exactly. There are two ways of getting a burnable fuel from water; the "water gas" reaction, which requires very high temepratures and a catalyst (carbon will do) to split water; or electrolysis, which works at ambient.
The main problem would be that the oxtgen-hydrogen mix, being stoic, is explosive and liable to detonate. Rapid dilution with injected atmospheric air would be needed to drop it below the LEL.
I'm not sure that the typical exhaust would be hot enough for the water gas reaction.. I will check.-- 8th of 7, Dec 11 2007 I will see if i can find a link to the mini steam generator and post it, although it was some time ago..-- riggers100, Dec 12 2007 Hey, steam would be cool - whilst the engine idles at a light - or better, is completely off - the cooling galleries become heat-soaked and the pressure of the coolant builds and builds - a coolant with a lower boiling point would be desireable for this.
The light turns green, there is a mighty CHUFF as the steam cylinders drive the car forward. It also cranks the engine round to start conventional operation.
It's like GM's "soft" hybrid, for stoplight shutdown only.
I think the Crower cycle would be a better choice, but hey.-- elhigh, Dec 12 2007 Sorry guys, haven't been able to find a link to the little steam generator. Thanks to [iron horse] for the BMW Turbosteamer link, I think that BMW are working hard to make their cars more economical to make them more desirable to the over burdened motorist, good luck to them. I do have some ideas for a steam generator of my own that I will post here when I have had a good think about it and have read more about the technical side of things.-- riggers100, Dec 13 2007 I like your thinking. +-- simonj, Dec 13 2007 Ok, I have done a bit of reading and found out a few things. Apparently the driving force for a turbine is differential pressure, the pressure on one side of the turbine is high and the other side is low. This causes the steam in the system to migrate through the turbine to the low pressure area causing the molecules of steam or whatever is being used to turn the turbine as they hit the blades. The Tesla turbine on the other hand uses the adhesive properties of the substance to turn the blades and is supposed to be more efficient although it has been largely ignored since its invention.
Ok, suppose we create a closed loop system that has a boiler (powered from the hot exhaust), a Tesla turbine, a condenser and a radiator to remove heat from the condenser. We then fill the boiler with water and pull as big a vacuum on the entire system as we can manage. This has the effect of lowering the boiling point of the water which in turn means that you have to put less heat energy into it to produce the required steam.
Arr, I hear you say, but as you create steam, you will be loosing the vacuum and defeating the object. Remember I said that it works on differential pressure, not absolute pressure.
For example, if I start at atmospheric pressure and I need 100 psi to drive the turbine, I will need enough energy to make the water boil at 100 degrees as that is the boiling point at atmospheric pressure, I also need to maintain the heat in order to create enough steam to give me my 100 psi differential above atmospheric pressure.
Now if I start the whole process below atmospheric pressure, I now need to put less energy in to make the water boil and produce steam, I don't know what the figures would be, but lets say you start at 50 psi below atmospheric pressure (can't remember the term for a vacuum, think it inHg, iches of Mercury but not sure). We can now make the water boil at 50 or 60 degrees and produce steam. The pressure in the system would build up as the heat was added until the system was at 50 psi above atmospheric pressure giving you the 100 psi differential pressure required by the turbine.
To extract the energy from the turbine, it would be constructed in a high strength none metallic substance such as Carbon Fibre or moulded bakelite ( the stuff they used to make electrical equipment from, not sure of the spelling) inside the housing, mounted on the rotating shaft are the generator magnets, and on the outside are the generator coils mounted as close a possible to the magnets, this would mean that there are no seals to loose the vacuum through by passing the rotating shaft through the housing.
Am I defecating in the wind here, or is there some way this could work?-- riggers100, Dec 13 2007 I have done a very rough sketch of the turbine idea at http://riggers100.50webs.com/ turbine.jpg The link wouldn't work when i put it on this page, so copy and paste it to your browser.-- riggers100, Dec 13 2007 //50 psi below atmospheric pressure //
There's definitely some wind defecation going on here.
Unless you're on jupiter, you'll only ever be able to go roughly 15psi below atmosphereic, which will be a hard vacuum.
However I don't think you appreciate some of the physics involved here. You can't cheat and pull a vacuum to run a turbine any longer than it takes to remove the vacuum.-- Custardguts, Dec 14 2007 I did say I don't know the figures...-- riggers100, Dec 14 2007 I still think the Turbo alternator is the way to go. I don't believe the electrolysis will draw more power than the HHO will put out.
The turbo alternator can easily put out 3.8kw much more with a twin turbo system. The department of defense had a unit tested in the early 90's creating power with rpm,s of 400 000 rpm. This means there is no limit in the standard automotive environment.
Obviously the power available will also reduce need for most if not all of the pulley systems in place on the very same engine. The power return from the reduction of pulleys will help with the final equation. The power lost from a pulley system is much greater than any power loss from a turbo.-- quickerest, May 09 2008 random, halfbakery