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We hear a lot these days about cars that produce low emission levels and run on energy sourced elsewhere, like hydrogen. However, few of them actually pollute less; they just pollute elsewhere. I have attempted to explain, below, an idea for a steam engine that could be small enough to power a passenger
car. This sort of thing would be potentially possible, and there is a design that has been trying to get out of my head for some time.
A low porosity ceramic combustion block/chamber with thin combustion tubules would produce a lot of heat and a large heat exchange area. This would in turn allow easy heat transfer to a separate steam chamber, comprising tubules bored into the other end of the combustion block at intervals between the combustion tubules. Embedded metal reinforcing would strengthen the tubule walls and increase heat transfer capability.
The combustion block would take the place of the existing piston crown assembly, with fluctuating but continuous, rather than sporadic, combustion initiated from what would be viewed as the underside of the piston, in current IC engines. Initial combustion may be by spark, but temperature and pressure would sustain further combustion, as they do in a diesel engine.
Partial volumes of the exhaust products are scavenged from the exhaust manifold and diverted to a reasonably high pressure forced induction pump (like a supercharger), to be reburned along with fresh fuel/air mix. Fuel delivery could be by common-rail injector, as used in most diesel designs.
The combustion chamber block is fixed, with a reciprocating piston at the other end of the steam chamber.
Use of small aperture tubules would largely prevent the cooler flamewall reactions that produce NO, CO and other pollutants as well as the previously inevitable unburned fuel, in existing internal combustion engine designs. As this sytem could allow the use of any sort of fuel able to be vaporized it would be very useful for those countries where nonane, octane and diesel are expensive or hard to obtain. It would also be very useful in developed countries where exhaust emissions are socially undesirable or subject to legislative limitations.
The work is derived from the steam generated, rather than exhaust gases, so the gases would be easier to capture and recycle, if desired. Steam pressures, at high temperatures, allow for very high torque generation, because of the high heat retention capacity of water vapor. Clean water is retained within the closed reticulation sytem, condensed in an atmospheric heat exchanger.
Lubrication would not involve oil, as it is generally unable to withstand the expected temperature load. The engine's operating temperature probably would exceed 1000deg C (1800F), in places. In that case, it would be better to use hydrophobic ceramics or coatings on the reciprocating components and bore sleeves. Steam would then provide the bore lubrication necessary.
Internal injection flash steam heat engine.
http://techref.mass.../mc-heat-inject.htm
Why do we always seperate the boiler and the cylinders? [James Newton, Oct 04 2004, last modified Oct 21 2004]
Green Revolution (Cyclone) Engine
www.cyclonepower.com
Modern high performance and highly efficient steam engine [devilishadvocate, Sep 26 2007]
[link]
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Maybe not terribly practical, but it's a very interesting idea flawlessly concieved, as near as I can tell. |
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I'm not so sure about the practicality issue. If the torque and power figures panned out the way I think they would then there would be a practical application, particularly if the mass of the unit was comparable to, or lower than, existing drivetrain masses. |
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A colleague of mine received a fairly substantial grant from some European Union scientific research fund to investigate what was I guess a very similar idea. They wanted to develop a steam engine small enough to fit inside a car. Even got as far as testing the prototype in the yard, before it let go quite spectacularly. Finances didn't stretch to prototype 2. |
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So you're not the only person thinking along these kind of lines [Zanzibar], although there are substantial challenges in finding suitable materials of construction. If you asked nicely you could even get someone to give you some money. |
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Based on what I understand about the industry I would expect it would require a public capital-raising exercise and USD$40 - 100M. I have seen a number of prospectuses for revolutionary engine design, in the past. |
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None of this stuff is cheap. |
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I imagine Aluminum Oxide ceramics would be most suitable. They are very tough (they are used for body armor and armored vehicles), an abundant resource (alumina) and are highly resistant to chemical action. Unfortunately, Al2O3 also has excellent refractory attributes. For that reason it is necessary to somehow facilitate enhanced heat transfer, as it provides very effective thermal insulation. |
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The biggest problem with steam cars has never been the boiler or the engine, but has always been the RADIATOR. That is, after the steam has done its work in the engine, it generally needs to be fully recondensed. (Most of the value of a STEAM engine is related to the enormous "heat of vaporization/condensation' of water at the boiling point.) Inside the engine-portion, steam expands and partially recondenses, releasing a fair amount of energy (remember that condensing water vapor provides the power behind hurricanes!). An ideal steam engine would recondense all the steam, but since none are ideal, a steam car always has a radiator to finish condensing the steam. |
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That radiator is very difficult to fit into a small car. If you decide your engine doesn't need to involve condensing steam, then you don't need water at all as your working fluid, and you will be surprised and somewhat disappointed at your engine's efficiency. |
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This reminds me somewhat of some ideas I had for an engine which didn't fit either the "internal combustion" or "external combustion" molds. The working fluid would be burned, but in a combustion chamber outside the pistons. The idea would be to pump air and fuel into the combustion chamber and then have the expanded combustion products go through a catalytic convertor and then through a set of pistons or turbines. From there, the exhaust gasses would go into a heat exchanger which would pre-heat the fuel at a spot after the initial pump stage. |
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Because many fuels give off large amounts of water vapor in the process of combustion, there would be considerable heat available for the heat exchanger to transfer to the incoming fuel. A multi-stage pump might be needed on the input so that the fuel wouldn't get too hot after initial compression (for pre-heating the fuel to add useful energy, the pre-heating should be done after the first pump stage, but the act of compressing the fuel will heat it, limitting the amount of heat the exchanger can transfer). |
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[Vernon], the radiator could be built into the floorpan of the car. It would be a simple matter to route airflow through it, with small scoops on the underside of the vehicle. It would improve chassis rigidity, too. |
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Not bad. When I first learned about the radiator problem (in an old old issue of "Popular Science" magazine), there was a suggestion of putting it in the roof of a car (they portrayed a station wagon design). Certainly this is a less "busy" place than the floor pan, but that is not to say a floor pan radiator is risky (leaks caused by flying road rocks, maybe).... |
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That's also a simple problem to overcome. A series of rigid blades to prevent incursion by larger objects, backed up by a short chicane in the airflow would stop small rocks & the like. |
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A floor pan need not be so busy. The floorpan designs used for some European cars with aerodynamically smooth undercarriages would be eminently suitable, I imagine. The subfloor spaces being designed into electric vehicles for battery storage nowadays are also ventilated from below, in some of the designs I've seen. |
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I can see this idea evolving in to a
Stirling Engine. |
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Not by me, you can't. All steam engines are heat transfer engines, [timbeau], and that includes fossil fuel power generation. |
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Hey great going keep it up and you might end up with a good working engine, For more research you might find the old books by N. Hawkins a great assistance, they are out of print but a few old book stores still have them. Also look for information on the Corliss engines they run more efficiently than most slide valve models. Condensers can be put anywhere by the way but the biggest problem I can see is freezing, after all you can't run a car all of the time and sooner or later the car must be left out in freezing weather. Some suggest leaving a small pilot light burning but what happens when it is out of fuel ? Even the strongest steel can't withstand the relentless pressure of freezing water. |
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I'm new around here, and my technical language is not of the best sort, but bare with me for a moment. |
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Nemo2, put a closed bottle full of water in the fridge and it goes bang. Put an open bottle full of water in the fridge, and all you get is some sort of a leaked icicle. Freezing temperature would require the water circulation system to be decompressed, or an emergency container... Leave pipes empty, boiler and main tank half full, emergency tank half full and with an emergency valve open. Or use a different liquid than water, if it's running in a circulation, that won't freeze. But it wouldn't be a water-based steam engine anymore. Maybe add alcohol to the water. Wonder what would happen. :) |
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Radiators. Okay, let's assume that the steam engine has at least two different containers. The boiler and the main water tank. Place the radiator in main water tank. Reduced energy loss because the water gets pre-heated in the tank, and if the heat is too big - a large fan and a radiator over the main water tank should do the trick. Water may need some space in the main tank, to allow pressure changes. |
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Steam engine needs a vacuum pump, so if it's present, the pump can be used to build a vacuum isolation over the combustion chamber. The idea is to capture the boiler and combustion chamber in vacuum, AND put them inside the main tank to reduce energy loss. |
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The great advantage of a steam engine may not be its efficiency, but the range of fuels it can run on. A hybrid that can burn wood, coal, dried horse crap, butane, hay, and other stuff would be indeed useful. Alternative for poor countries. Perfect for farming. It does encourage people to consume their surroundings, but you can't have everything...
I guess it is enought to raise the temperature in the combustion chamber and everything will burn provided with oxygen. But how to dispose of ashes, reducing energy loss and not setting anything nearby on fire?
How about a grinder for 'stale' fuel? |
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Can't a different liquid than water be used in a steam engine? |
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Nemo2... the relentless pressure of freezing water... you know what, I guess the freezing air could be used in favour in the engine... Steam shrinks when cooled, remember? |
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[zanzibar] seriously speaking i can imagine that every moment you just think of nothing else but novel ideas. i don't know where you are from but suggest you should get associated with some body that may help you carry out experiments. |
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Misza: Think water pipes of your house when thinking of freezing or perhaps a pool pump. Also water is used because of its consistent expansion after it is turned to steam and also because it is less poluting. To add alcohol or other antifreeze would change the boiling point and expansive properties of the water, also when they are boiled away alcohol and ethelyne glycol antifreze leave a residue that would eventually clog up the boiler. |
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[Zanzibar] do you write patent applications? That sounds just... wow... but a picture would sure be nice for us simple folk. |
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I used to work part time in a patent attorney's office for a few years. I guess I picked up a little of their methods and grammatical patterns. |
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DaS Energy, agrees steam is the dream energy. |
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Addition of water with any fuel creates flash steam. |
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However steam cleaning rids all lubricant, when performed in a piston or other friction loss engine. |
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Turbines not having the friction loss parts of a piston engine are obsolved of this problem. |
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Water is more solid than metal. I may be used as a piston. But not in the current piston manner. |
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1300c combustion waste heat of Diesel may fuel steam. Both the combustion and the steam may force upon water which may rotate a turbine. |
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The entire workings may be confined to water valve and any hydro turbine. |
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The principal of gas is but a boat on water, which may travel also by loch. Plus always seeking elevation. |
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May chase itself in a circle, with diversion into a gasses filled down dead end for comprsession. Before forced back, then continuing around. The trapped compression, may seek escape following the water and get blind ended, squeezing itself so hard it combusts. |
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The spent gasses from combustion may be forced out by the water flow it has created. Before the compression finds its way to combustion. |
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why not just get a nucular reactor and fit it into your car and harness the steam that way
and then you could also say what the "whats the half life of your car" |
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why not just go open loop and vent the steam? . Fill up with demineralised water and methane (or whatever your fuel is) at the servo. IIRC the volume of water consumed by a high efficiency turbine system is fairly low per kWh. |
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An added advantage is that ultimately the increased water vapour into the air may change the microclimate of large cities. maybe. |
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