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The heat lost by internal combustion engines is pure waste. If a deisel-type injector were programmed to inject just after ignition the exactly right amount of water to maintain a temperature of, say, 150C at the exhaust valve, the latent heat of evaporation would keep the engine at the right temperature,
and the expansion ot the water droplets into steam would triple the work obtained from the fuel. The cylinders are insulated to conserve the heat, not cooled as currently done. The exhaust gases are, however, cooled to condense out the water again, which is returned to the reservoir via a purification column, leaving very innocuous residual exhaust fumes, and very quiet exhaust note.
(?) water injection
http://www.aquamist.co.uk/
[1978tomy, Jul 21 2000, last modified Oct 21 2004]
(?) More water injection
http://www.510again...ering/watering.html
Water injection for turbocharged engines [mwburden, Jul 21 2000, last modified Oct 21 2004]
Device could aid production of electricity
http://web.mit.edu/...ctricitydevice.html
[from Slashdot] "For example, the heat lost through engine exhausts might be captured by the technology and converted into electricity to augment or replace a vehicle's electrical and air conditioning systems." [egnor, Dec 02 2001, last modified Oct 21 2004]
Flash Steam-powered Engine
http://www.flashsteam.com
Yup. It works. [galukalock, Oct 17 2004]
Smokey Yunick's Engine
http://schou.dk/hvce/
The Adiabatic Engine [dlapham, Oct 17 2004, last modified Oct 21 2004]
Internal Combustion Steam Engine
Internal_20Combustion_20Steam_20Engine
Not the same thing at all. [phoenix, Apr 19 2008]
[link]
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Whould this end up being less efficient during the cold months, since you'd have to thaw your water supply? |
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I like centauri's negative view of this engine. Injecting a fluid such as water into a combustion chamber would be totally pointless and would ultimately provide the opposite effect that would be required in a powerplant such as the internal-combustion engine. If your meaning wasn't to inject the fule into the combustion chamber then you are adding more parts onto the engine all these parts require energy. You would probably (if magical) have just enough power generated from the steam, to power the extra parts that your engine requires. |
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"Waste heat recovery systems" are widely used to increase the efficiency of heat engines. These systems are often steam boilers, but sometimes use thermoelectric generation or some other wacky technology. They are considered an environmental boon and a cost-saving measure at the same time, because they reduce fuel consumption. |
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However, the complexity of these systems generally limits their use to large stationary installations (think factory smokestacks); I haven't heard of anyone trying to mount a serious waste heat recovery system on a car. In any case, the laws of thermodynamics place a theoretical limit on the amount of energy you can extract. |
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The most efficient way to use waste heat is as *heat*; rather than extracting energy, use it to keep people warm in the winter. This is also common in stationary installations, and of course in cars as well. |
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Nope. Basic thermodynamics says the efficiency is directly related to the temperature difference (even for steam engines). Higher temperature = more efficient. Recent internal combustion research is looking at ways to increase the combustion temperature, for instance by using ceramic engine parts that don't melt. Higher temperatures also can be used to reduce pollutants like NOx, CO, and particulates that are the result of incomplete combustion. |
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It's true, the hotter the engine is running, the more efficient it is. There are some exceptions though. You don't want to get components that cannot handle the heat to get hot. What about putting heat reflectors throughout the engine compartment, and wrapping sensitive components in heat shielding. A sort of thermal oven with the parts that cannot take the heat insulated by AeroGel or something. |
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I had lots of quibbles about [rmutt]'s thermodynamic analysis here, but let's ignore all that. |
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For whatever reasons, ** internal combustion engines have cooling systems today! ** Theoretical arguments from half-understood thermodynamics courses aren't relevant; the reality is that practical considerations mean that *engines must be cooled*. Forget your textbooks and look under the hood! |
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Tomorrow's cars may well operate at higher temperatures -- maybe even high enough that they won't need cooling at all -- but last time I checked, cars still had radiators. So, as long as you're pumping that heat into (what's basically) a boiler, it stands to reason that you could use it to drive a secondary heat engine. |
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Once again, however, (as far as I can tell) practical considerations enter the scene to prevent automobiles from using waste heat recovery systems. As noted above. |
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I'm forced to put on my Thermodynamics Hat and agree with Egnor and Rmutt. You'll probably never be able to squeeze out more than about 40% (caution! made up approximate number!) of the fuel's chemical energy as mechanical work, which leaves 60% to get rid of as waste heat. That's a lot of heat, hence radiators. Possible uses for that heat on vehicles would be cabin heating (obvious) or cooling (raise low pressure steam to drive a steam injector refrigeration cycle rather than driving the aircon with a motor powered by the engine). But then you might end up burning more fuel if the heat recovery equipment is much heavier than the conventional equipment to do the same job. It's all a delicate balancing act (as well as a plumbing nightmare). I've just reread all that and I'm not sure I've added anything new to this discussion. |
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Popular Mechanics has mentioned a couple of times making engines out of ceramics, so they don't need seperate cooling systems. They'll still give off heat, but they won't need radiators and water pumps and so on. |
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How about building a bunch of peltier type elements into the body of the engine and turning the heat into power? <Peltiers are transistor devices that, when power is applied, transfer heat from one side to the other. Useful in cooling computer CPU's. But applying a heat source to one side will produce an output voltage... |
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I keep losing my annotation - choice phrases gone for ever. My fury remained - I have never seen so much knee-jerk negativity in my long life. You must realise that the lack of exploitation of the idea isn't that industry didn't appreciate the potential of using all that waste heat for more power - the technology wasn't then available (except in spitfires for extra combat power, when an aerosol of water could be squirted into the inlet manifold - not for long, though, lest it wreck the engine). Now times have changed - we have deisel micro-injectors that can meter and time the dose to perfection - to follow the flame front throughout combustion, in exactly the right amount to give an exhaust-gas temperature of, say, 150 C. The radiator can be used to recondense the water which can be re-used after purification. Come on, industry, make it for us; in these eco-times we need the fuel efficiency, the power from all those calories in our gas, and surely we can get the fat-cat oil barons to reveal all the patents they snatched to stifle. Don't listen to the puny objections you can see in response to this proposal; no progress will be made with that horse and buggy outlook. |
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rmutt: Running engines hotter does indeed reduce CO and HC emissions; it has the unfortunate consequence, however, of /increasing/ NOx emissions. |
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Otherwise, what I'd like to see would be a cross between an internal-combustion engine, and external-combustion engine, and a jet. Specifically, have the crankshaft operate two pumps, one for air and one for fuel. The air and/or fuel are then passed through a heat exchanger and then into a combustion chamber. The consumed fuel then passes through the drive cylinders or turbine, and finally through the above-mentioned heat exchanger. |
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Key notes: [1] any expansion of pre-combustion gasses caused by the heat exchanger will be turned into useful work; [2] the combustion products of hydrocarbons include a lot of water; condensing this water will release a lot of latent heat; [3] since the condensation of exhaust gasses will occur in the heat exchanger which is after the drive cylinder/turbine, the substantial reduction in exhaust volume would not be a problem. |
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Actualy I think you are thinking of the adabatic cycle
excuse the spelling Dr. Diesel was attempting this with coal injection when (1903) he invented the diesel |
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I remember high compression engines ran better when it was raining, more power. Materials would definitely have to be changed as there are hydrogen generators based on steam. At elevated temperature the oxygen jumps ship leaving the hydrogen free. Iron > iron oxide was one of the methods. |
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Well, actually, about 20 years ago I knew a guy who was working on this idea. If I recall correctly, he built a working model from a lawn mower engine. The idea is this: in an ordinary engine, igniting the fuel in the cylinder causes expansion which moves the piston. Injecting water right after this burn (timing is crucial) turns the water into steam, creating more expansion and more movement of the piston. The problem he ran into wasn't making the engine work. Scaling it up to make it work in an automobile would require carrying along a huge tank of water - too much volume and too much weight. Hedley mentioned recovering the water vapor from the exhaust to reuse it, but I'm not sure how well that would work. Could you cool the exhaust, condense out the water, and still get rid of the exhaust quickly enough? |
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Isn't a turbocharger a more direct way of using the waste heat? |
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It should be noted that burning hydrocarbons already produce a lot of water in their exhaust. In fact, the mass of water produced by burning methane, ethane, propane, or butane is greater than the mass of the hydrocarbon consumed (the rest of the mass comes from the oxygen in the air). |
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Turbos don't use the heat, they use the pressure of the exhaust gas. Heat is something turbos have problems with, which is why they require their own oil systems to keep the bearings from melting. |
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This has already been tought of. They're still trying to get it to work well. |
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There is another direction to go. Rather than using fuel mixed with water, just use steam. |
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The old steam engines used a piston to provide power, so four pistons together should give four times as much torque. |
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You'd still need to heat the water somehow |
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The other problem you will run into is lubrication.
Steam in a super efficient scouring cleaner, so it will rip the oil off the piston wall and rings, and your engine will end up seizing...
The old steam engines, I suspect, avoided this problem by having loose tolerances and operating at low (piston) speeds |
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I was thrilled to stumble on this web site, It's like brainstorming with like minds cool! anyhow, I feel any endeavor to increase efficiency of our motors is worthwhile, and I have visioned down the same path many times. Much of what I read above consists of current technology in some form or another but would struggle to compete with a simple turbo setup, so I suggest if you can't beat em, join em and add this idea to a turbo setup :
A special heat transfer exhaust system consisting of the exhaust manifold, turbo, and most importantly the catalytic converter which gets very hot, used to convert water to steam which would drive a turbine/generator. What you do with the power is open for suggestion. |
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Rather baked. Though SAAB use water injection
to reduce emissions. |
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Unlikely to condense water out of the exhaust without an immense heat sink ( the heat has go to go somewhere..! ) |
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If you have the coldest possible fluid entering the cylinder, and heat it up as much as you can stand within the cylinder, then you will get the greatest possible ratio of expansion/pressure rise within the cylinder.
According to my grasp of thermodynamics... |
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http://www.autospeed.com/A_0115/page1.html |
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In my understanding of modern day cars, the reason for cooling is to prevent oil breakdown, and metal fatigue. also if the engine is too hot, it will combust the gas before the ignition of the spark plug, igniting at the wrong moment.
As furmobile said, in theory, the coldest material ignited at the highest possible temperature would expand the largest distance. If we could find a way to keep the fuel at the coldest temp, before ignition, then be able to ignite it at the highest possible temp, would require less fuel to do more work. Hence reducing the amount of fuel used, and furthermore reducing emissions. |
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That's part of the reason for intercoolers. Turbochargers compress the intake air, so it heats up. The intercooler cools it again so it's denser. |
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For diesel engines can we have another pump similar to conventional Fuel Injection Pump. But this pump will be used to inject water at a specified time in to the cylinder through the same nozzle through which fuel is injected in to the cylinder. (Timing of injection to set carefully)
So in the later part of expansion stroke , small water particles can be injected in to the cylinder which can expand and give some additional push on the piston |
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A internal combustion engin can actually be made that
runs of pure water. I dont know the specifics and I'm
sure there is web pages on it although... it could be just
a story, anyway here is how it works. Water is injected
into the cylinders and then zapped with a high powered
microwave, this microwave is shot off using some sort of
stobe light timer, this is supposedly more powerful than
conventional engines and compleately envromentaly
friendly. One of my friends explained all this to me when
he was planning on making one, he never got around to it
but apprently there are plans on the internet. The guy
who designed this engine that would revoloutionise the
automotive industry got his design bought by oil companys
and they are sitting on it for obvious reasons. The only
problem I can see with this engine is that it would
probably use a huge amount of power but then I don't
know much about microwaves. Can sombody either pull
me up on this and say yeah its just a urban myth or is it
true? |
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You way you describe it, this is not an internal combustion engine, it's a steam engine. Internal combustion engines cannot run on water because water does not burn. |
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Sorry I meant it dosent differ alot from an internal
combustion engine in that the difference is it runs on
water and the steam is still used to drive the pistons, argh
what am I talking about I dont know shit about engines,
but I can see how the microwave and the water could
replace a spaker and petrol. |
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I did't mean to replace fuel and spark. What I thought was to make use of heat energy in the later part of expansion stroke. This heat energy will be used to convert water droplets into steam. These water droplets ,because of fineness of spray , will be in suspended form. Once they are converted in to steam , huge increase of volume will take place. This will give additional push to piston
Thus we will get work output in two stages
(1) Conventional expansion stroke of an IC engine
(2) Steam energy ( obtained from heat eneygy in the later part of stroke)
I do not know whether I am able to express it.
Please revert back |
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No I know you didn't this is somthing similar I have heard
of using pure water and super heating it with microwaves. |
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Gulherme: What is the rate of heat release by microwaves considered by your friend. Have you seen his heat and mass balances? |
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The first two links don't relate to increased efficiency.
And the third link depends on the exhaust being hot. It is possible to design an internal combustion engine so badly that it runs better with water injection, but it won't beat a properly designed engine, in my opinion. |
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Excuse me for coming into this so late, but i would like to add my piece.
Hedley's idea is good but the way he wishes to carry it out is not sound.
an engine that uses steam as a secondary power source is a good one.
The best way to carry this out would be to build a 6 cycle engine. The first four cylces being like that of a standard internal combustion engine. The last two would begin at the end of the exhaust stroke. After the exhaust valve closes, water would be injected, it would expand in another power stroke, then the exhaust valve would open, leeting the steam out. For this to work effeicently the water may have to be preheated by the cooling system, and a higher than normal temperature thermostat may have to be used. |
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I've read extensively on the idea of injecting water into an internal combustion engine. Several problems arise. Already mentioned were the water storage, and the fact that water doesn't burn. At the point of ignition, there is a great amount of pressure in the chamber, forcing the piston down, any attempt to inject water into the pistion would result in the pressure escaping through the means you meant to inject water. Even if you were able to get the water to enough pressure to actually inject it.... has everyone forgotten about how corrosive water is? Bare metal and water... hmmm.... not to mention the level of oil contamination. It's not feasibly or reasonably possible for this to take place. |
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To address the engine that runs on water, yes it does exist, but not in the way described. A water tank has two electrodes going into it, when electricty is passed into the tank the water splits ito its respective gases, oxygen and hydrogen, I can't remember which goes to what polarity at this time. the gases pass into seperate holding tanks and metered into a gas turbine for use. Unfortunately the reaction doesn't happen quick enough to power the engine for extended periods. |
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I'm currently into the second stage of development of my own heat exchanging engine. I'm using the heat from the water to heat the gasoline. Hot fluids expand, it also allows the fuel to atomize more readily with air for consumption, reducing amount of fuel needed, reducing emissions and the like. Second, I'm now installing a heat exchanger to use the water from the thermostat (device that controls engine water temp) to heat the air through a duct going into the engine. I'm running an old 77 dodge pickup with 35 inch tires and a 4 barrel carb, and getting 26 miles to the gallon doing it lol. Study up on your physics.... its easy to over look the obvious. laters for now. |
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surely heating the air makes it less dense and reduces the oxygen per volume making the bang smaller |
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There are a lot of good ideas but a few major flaws.
1. Making steam in the cylinder would couse the lubricating oil to brake down, resulting in eng. failure.
2. Given the presure inside the cylinder during combustion, water would vaporize during the exhust stroke, insted of the power stroke.
3. Atempting to condence and reuse the water would be a dirty, and cumbersom task. |
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One thing for shure, there wouldnt be any carbon build up! |
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Lets face it an internal combustion eng. is not efficant. Finding a different method of using hydrocarbon fules is needed. |
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Sorry for the "no sayers" but this thing already exists as a prototype ! |
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But the steam is produced outside the engine in a heat-exchanger by the hot exhaust gases as the engine is not cooled very much.
It will be made by Wärtsilä, a big boats engine maker from Finland.
It's called a "Steam-injected combined cycle Diesel".
Picked-up from some website : |
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""Lower CO2 emissions are equivalent to better fuel consumption. Raising efficiency beyond 50% requires a diesel combined cycle which, to be feasible on a diesel engine, means changing the heat balance a bit. This is done in the hot combustion concept,
where the piston top cooling and the cylinder head cooling are eliminated, and the cylinder liner cooling is minimised.This makes it possible to elevate the exhaust gas temperature after the turbocharger by more than 100 degrees Celsius,
and significant volumes of steam can be produced. This steam can be used in a steam turbine or to boost the engine according to the steam-injected diesel concept. One 12-cylinder Wärtsilä 64 engine and one 12-cylinder Wärtsilä 46 engine are running in a pilot power plant in Vaasa, where the concept is being qualified.
When applied on bigger installations it will be possible to reach about 60% efficiency with the diesel combined cycle concept and maybe 55% with the steam-injected diesel concept. Wärtsilä believes
that these values can be beaten only by further development of the same concept ."" |
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Althought, your idea of "in-cylinder steam production" is really great, i also think about it for some time ! |
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There are 2 main reasons that IC engines have cooling systems.
1: Not all of the parts can handel extremely high temperatures (such as valve seals and non-metal head gaskets). |
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2: (And this is the main reason) Gasoline has an octane... octane is a measure of how the fuel resists "pinging" or "detonation" ... that is pre-mature combustion of the fuel. |
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Too much heat in the cylinder will cuase the fuel to combust before the spark fires (and thus befire it is supposed to, losing power and over time causing irrepairable damage to the engine) also, during pinging the fuel fires even hotter (tends to "burn" as opposed to combusting) And can burn holes in valves or valve seats... or even pistons. |
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The higher octane the fuel, the less of a problem this is. Also the more readily you can pull the heat from the cylinder, the less of a problem this is... that is why aluminium block+heads will handel higher compression on a given fuel than iron will. |
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But up to that "pinging" limit the fuel combusts more efficiently as the heat increases. |
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Because of all this, 97 oct fuel will make more power and be more efficient than 89 octane fuel even though 89 contains more potential power, it's much harder to get. |
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I believe the right way to solve the problem of pollution from IC engines is to run them on hydrogen, which can be readily obtained from offshore solar/wave-energy/wind powered electrolysis plants and delivered onshore by gas pipelines. |
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Similarly the public could take over this role themselves by installing household, grid connected electrolysis plants in their own garages. Although grid power is probably even more of a polluter then car exhaust. |
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"Excellent" maybe but hardly original! This is not the place to talk about hydrogen vehicles, go to one of a million forums which do nothing but that. |
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have only just come across this site. very interesting. have been thinking along similar lines for a wile.
seems to me you want to inject water into the IC engine as hot as possible, say 200degC, just below the critical temp. because we dont want combustion heat in the cylinder to be adsorbed in latent heat. The purpose of the water is to allow the gas/vapour in the cylinder to expand to large volume , still high pressure , but low temp. because we want to minimise heat lost through the cylinder walls. The cylinder walls cant realy operate much above 100C because of the mechanism and lubrication.
The exhaust gas can be condensed and the heat taken out by contra flow heat-exchanger, which heats the water after going through a pump.
Direct injection 2 stroke would be good for this, small loss of heat to cyl. walls.
It is obvously better to use hydrogen from wind power, but want effecient fuel cell, or maybe we can make engine effecient for using it. |
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there are people going off in several different tangents here, the thread realy needs to be split up.
(1) There is the issue of whether and how water can be used in an IC engine to obtain the same expansive force at a lower working fluid temperature. On this issue people should ignore problems like lubrication, corrosion, recovering exhaust water, size of plant ; these issues can be addressed when it has been proven to general acceptance that this method can be used to increase thermal effeciency. On the above topics I think we are assuming that the accepted laws of thermodynamics and chemistry hold. It is clear that there is some misunderstanding of these laws, but we need to bash the argument into shape so it is based on the laws which give workingly accurate models for existing engines ( I don't claim to be an expert on this). |
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(2) On engines which run on water, I don't think this is possible under our accepted science. But there are these romours of people having done it. I attempted to search for information on this a few years ago, but people seem to have different schemes, and there is no clear description of any of them. "cold fussion " is an example. Obvously if these things are possible it is absolutely ground breaking - both in terms of stoping global pollution, and in our understanding of science.
This topic is realy interesting, but we can not discuss it within the accepted laws of thermodynamics, chemistry etc. |
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I would like to contribute to the IC steam engine discussion, is there a way of separating these now different discussions ? |
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You have got the thing running! now what are we talking about here. Are you saying that this engine is producing more mechanical power at the crankshaft than you are putting in to vapourise the water with the mannetron ? i.e. the electronics runs off a generator on the engine ?
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Now if this is true this is somthing of world shatering importance. Also you may be in great danger as people making similar claims, have in one roumor I heard of been murdered and all traces of their equipment destroyed.
Can we have some more details please.
paulb2 and paulb3 are same forgott the damb password |
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we have not seen your thing on the UK news yet. If this thing is working as you say with no fuel other than water you should get it on the media right now. It does not matter that people have claimed things like this before, this is beyond science.
You must forgive me if I am sceptical. A thing that does not sound correct is your magnetron/points circuit. The magtron has low voltage AC between its two cathode terminals, for heater- this takes seconds to cool and heat there is no point in switching this. The main supply is around 3000V this is what you would want to switch, but will the normal points switch this without arcing when open ? |
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Dang, I calculated that wrong. It should be more like 180 * 1.5 *.6 * .4 * .3, or about 19 hp. |
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Sorry, forgot about that magnetron, I was thinking steam cycle engine. I still you'd want separate cylinders to accomplish this, though. It'd be shear luck if the the temp. properties were in the right range and the internals of the cylinder would live happily with constant water flooding. I take it the EMU oil is an additive to raise the boiling point? |
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What about the whole 'magnetron + metal = fireworks' problem? Got a way to isolate? |
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Back on this thread of normal engines benefiting from water :
Is there that much water in fuel ? or is that a lorry drivers anicdote ?
water and oil have no afinity for each other, and different specific weights. Diesel engine fuel systems have water seperators, these would just fill up if there was that much water in the fuel. |
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An IC engine expands a mix of steam/nitrogen/CO2. This gas wants to be as hot as possible at the beginning of the expansion. If more H20 is used you do not want cold water you want it as hot as possible and at high pressure so it stays water. cooling is only necessary to keep the mechanical bits (cylinder) at practical temp.
If cold water is added it adsorbs a tremendous amount of heat before it even turns to steam ( bear in mind the pressure, so it does not boil untill very hot) heat that has been used to heat the water is then just carried out the exhaust port as waste. |
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First, the idea of water injection is very old and does in fact
work. I have always wondered about the long term effects
on the engine due to corrosion, but the claim is that it
actually reduces engine wear. Very simple water injection
systems can give modest increases in mileage and there are
a number of plans available on the internet mainly focusing
on carburated vehicles. |
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These systems are generally rather simple, not a dedicated
injector in the combustion chamber, but rather systems to
add a mist of water into the intake. |
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The idea is similar to a cold air intake, the purpose is to
provide a denser, cooler charge of air for maximum
expansion. Water injection is of course even more
effective. |
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As for fuel temperature, one of the major problems with a
gasoline engine is that it is difficult to get proper
atomization of the fuel to provide for complete
combustion. An article in (i believe) HotRod magazine a
couple years or more ago detailed a guy's system "hot fuel
injection" that used a channel around the exuast valve seat
to heat the fuel into a purely gasious state (no longer in
need of liquid atomization for combustion) and then
allowed it to pass into a similar channel in the intake valve
seat. holes drilled around the intake valve allowed fuel to
pass into the combustion chamber as the valve lifted.
variable valve lift by a moveable fulcrum controlled the rate
of fuel flow. |
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A very interresting system, though converting a vehicle to
natural gas would have the same effect and is far simpler
and easier to do. Natural gas does not suffer from the
atomization problem, and is rated at approximately 130
octane (i believe) which is much gentler on the engine due
to the slower combustion. Also, being cleaner burning (in
addition to the environmental benefits) there is no carbon
buildup in the engine and engine oil lasts longer. |
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I know that GE has experimented with steam (known as STIG) and water injection on large gas-turbine engines and has found that there is a significant increase in cycle efficiency. While it is true that the lower combustion temperature decreases the basic cycle's efficiency, the increased mass flow due to the water's high density more than makes up for it. Not only that, but it would probably greatly reduces NOx. The concern I would have would be on the condensation of the water in the exhaust system, which carries a very high concentration of SOx, which tends to eat away metal (this is why waste recovery systems in plants are limited to cooling the exhaust to about 350F). Solve that problem, and this would be a great idea to experiment with. As for water mixing with oil, there are plenty of new and old ideas on how to separate the combustion chamber and oil sump. As for ceramic "adiabatic" engines, all the research that I've seen only shows that cutting the heat lost through jackwater cooling (which is only about 15% anyways) ends up as higher exhaust temps, not more shaft power. To convert this energy into shaft power, it requires a gas turbine in the exhaust connected to the output shaft, as well as a turbo charger. |
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If anyone's still following this discussion: |
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All other issues aside, water simply doesn't boil explosively enough for the small amount you could inject into the cylinder after ignition to generate much power. |
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Injecting water BEFORE ignition, as has been pointed out, allows for a cooler and denser fuel/air charge, which helps a little. You really need to increase the engine's compression ratio to take advantage of it, though - this is basic turbo/supercharger stuff. See www.vortech.com to start... |
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If the fuel/air mixture in a gasoline piston engine gets too hot, it will detonate ("knock") on the compression stroke - period. This can be combatted with octane, to a point , or with lower compression, which kills your power output. The theoretical benefit of retained heat in an engine simply can't alter this fact. Detonation kills piston engines and heat causes detonation. TIMV - if you preheat your intake air, either nothing will happen (if you're lucky and your pistons are leaky and your compression is down) or else that Dodge will knock itself apart. No good will come of it. |
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The microwave/water thing is crap - ever tried to boil a cup of water in your microwave? Takes forever;) More importantly, it takes more energy (as electricity) to generate the microwaves to boil a given mass of water that you can collect from the expansion of that water. So it won't work. This whole concept of "cracking" molecules and somehow magically getting an exothermic reaction has no basis in reality - it's a pipe dream based on people not quite understanding how fission works. Do a search on "Brown's Gas" for great examples of deluded backyard nuclear physicists. |
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At the risk of giving people ideas, I'll elaborate. (Please don't try this at home. There, I said it.) |
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The 'microwave-a-cup-to-superheat-it- so-you-can-seed-it-and-watch-it explode' thing only works if you use a glass (or very similar material) container. You must nuke it for quite a while, enough to get it well past boiling. Then, stick in *any*thing that doesn't have a perfectly smooth surface (creamer, fork/spoon), and blam happens. |
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As for the maser thing, I dunno. Seems to me that the water injection (flash steam) thing would work better. |
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Earlier works done at SwRI for the Army involved the idea of injecting water directly into the ICE cylinder to provide complete engine cooling. Of secondary interest to the Army was the notion that they could increase engine performance. This information is public knowledge. |
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Direct-cylinder water-injection can vaporize water in an IC engine. The latent heat needed to vaporize the water comes from two sources, the in-cylinder components, and the fuel energy. The timing of the spray will tend to set which energy form is dominant. The added expansion work of the steam may benefit the Brake Specific Fuel Consumption. It is effectively combining the Otto/Diesel cycle with the Rankine cycle, using the same cylinder space for a bottoming cycle. |
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The SwRI experiments involved a standard four-cycle CI and SI engine with water injection timed at varying crank angles and quantity. This gave data for a family of performance curves for the engine. The largest increase in BSFC happened with water injected on the compression stroke, reducing the energy to compress the charge. Two things came out of the report that you may find interesting: |
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For water injected mid way in the power stroke there was little change in the indicator diagram for the rest of that stroke. It was proposed that the reduced pressure of the combustion exhaust opposed the pressure gains made from the steam. Calculations showed that the magnitude of the pressure reduction caused by cooling the exhaust gasses is six times as great as the pressure gain achieved from the formation of steam. Whatever heat energy can be recovered from the in-cylinder components benefited the net pressure. |
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A heat exchanger must reduce the exhaust temperature to about 100 Deg. F. to recover all the water needed for water injection for in-cylinder cooling. This means a very large air-cooled condenser, making mobile applications difficult in warm climates. Of some interest, the old rigid airships used exhaust water recovery to ballast the fuel burned by the engines. The low ambient temperatures at the altitudes the airships cruised allowed for compact heat exchangers. |
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I’ve looked at some patents involving direct-cylinder water-injection. Some appear to rob rich combustion energy from the combustion power stroke to give to the poor energy of the steam cycle (Robin Hood Cycle). Examples include engines that have fins in the cylinder head in direct contact with the combustion gases and the injected water. Perhaps these patents have surfaced because, although the waste heat quantity is high, the quality of the temperature of the combustion chamber walls is insufficiently low to vaporize all the water. |
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Thank God!! I've found an intelligent thread on here.
A few notes.... |
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The quantity of heat in the exhaust is immense compared to that lost in your car radiator. It would take a hell of a cooler to condense the exhaust water vapour. We're talking the entire vehicle underside here, and probably roof space as well. |
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A separate cylinder to use the exhaust heat can be run as a pure traditional steam engine: its dedicated for it and can be efficientised in every way. The IC's exhaust is used to run it. The steam cylinder is on the same crackshaft and kicks in with a bit of time lag compared to IC section. |
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The problem is simply that the power/weight ratio of steam power is so much poorer than IC, that you'd end up losing out. Yes you get a little more power per gallon of fuel, but all the extra weight you have to carry kills the advantage. It works in a stationary engine, but the extra power is not huge, whereas the increase in engine size/weight/cost is. |
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Combined steam/fuel can also work on boats where engine weight is not a significant issue, and condensation is easy, but not in cars. And its mucho cost on the price of the engine. |
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The Stanley steamer was never efficient in the true sense of the word, it was just economical. Power output was desperate by modern standards. If you build a modern engine to the same performance specs as the Stanley you get way over 100mpg. If youve ever driven something with similar specs to the Stanley you'll realise its in another league entirely. I have, and I'd never drive something like that that on the road again. I understand why the Stanleys are so thoroughly extinct, unlike most vintage cars which have survived here and there. |
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Prewarming is standard practice in cars now, and is achieved by the EGR valve. Hot exhaust is only mixed in at mid power settings: at high you need cool input products in order to get lots of it into the chamber. At low power settings I forget the deal, but again you dont want preheating going on there. My 1980s car used this preheating method. |
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There is some interesting research done by DaimlerChrysler rearchers at the University of Michigan - Madison on direct water injection in a diesel engine. |
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http://www.cae.wisc.edu/~rutland/research.dir/NOx_water/2000-01-2938.pdf |
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They disuss the physics, injection technolgy and emissions / effieciencies under varying loads. They conlude that under the right economic conditions this is a viable technology. |
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I am relatively ceratin that the main reason for engine cooling at this point is due not to metalurgic or engineering limitations, but to the limitations of the standard octane gasolines available at the pump. Remember when we had to put high octane gas in our supercharged engines to prevnt misfire? Well presumably there is a temperature range above which 93 or 94 octane gas will combust without a spark. This considered why not use the heat of the engine provide steam pressure which could then turn a device like a supercharger or turbo charger. Maybe some sort of radiator, a metal box if you will that would draw heat from the engine, or exhaust. then be injected with water to create bursts of steam which could be turned into maybe enough pressure to neutralize the negative psi in the air filter box. |
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The idea of water injection into an internal combustion engine was incorporated into World War II fighter planes that took off from aircraft carriers. Ithink it was the "Wildcat" which had a radial engine. it was a rather heavy plane so it needed a boost to take-off over a short distance. The "boost" was given by injecting water spray into the cylinders during take-off when the engine was nice and hot. This provided enough increased pressure to increase HP for the short burst needed. I think that longer term use of water injection ebventually interfered with combustion, lubrication and was too heavy. |
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I remember some kits they sold for cars that sprayed little amounts of water into the engine inlet (usually a perforated ring around the carburettor base) and it actually worked some. It's true, though, that engines work better with high humidity and some WW2 figther planes had water inyection systems.
Much better to use an external combustion (say, a water steam) engine. The trick isn't in the engine but mostly in obtaining a really small and efficient steam generator. Skoda has recently done something on these lines. A plastic steam piston engine could be made maintenance free and will no need clutch or gearbox.
A very high steam temperature would insure a good performance and therefore minimice heat loss.
So, when are we going to make one? |
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I would have to agree that its a complicated matter. However there are a few points to address. The pistons have multiple rings because they serve multiple purposes, the top ring maintains chamber pressure and minimizes exhaust and raw fuel from entering the oiling system, the oil rings include a scraper which removes nearly all traces of oil from any leverl above it, the combustion chamber on an unworn engine has nerely no exposed oil at any time. If even a single drop worth of oil were present during each stroke your car would smoke like crazy and run out of oil long before your next scheduled oil change.. This negated the point about steam cleaning the engine too much. Next I have to agree witht he gentleman about it being more effective to have a multi cilinder engine such as a v6.. the best meathod would be to run the fuel air mixture lean to generate more heat during the combustion stroke of the first bank of cylinders, have those exhaust into the intake of the next bank of cylinders where water mist is injected. There are already diesel engines which reuse expanding exhaust on a second set of cylinders for enhanced efficiency. |
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[evil_that_I_do]'s extra steam cycle: sorta-baked by Bruce Crower: (Wikipedia entry) http://tinyurl.com/2esp48 (or search for "Steam-o-lene"). |
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Steam from exhaust heat: sorta-baked by BMW: (PopSci.com article) http://tinyurl.com/qtjex |
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I don't have any input on the main idea. |
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Half-baked - As mentioned SAAB had an add-on water injection system that added about twenty HP to a ~150HP engine. I say half-baked because they did it for a different reason, they did it to slow combustion/stop predetonation, so they could run more boost. The idea is still good though it has issues because the water affects the combustion and aerodynamics of the engine air. |
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So what's happening 6 years later. Why don't we see this happen? [Hedley] you get my Positivity+ |
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The theory here is sound - except for the part about reducing the temperature to 150ºC. But as others have pointed out, it's also been kneaded, proven, baked, and toasted into croutons. |
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//Why don't we see this happen?// |
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Probably for the same reasons as desmodromic valves and exhaust-powered alternators are rare. They are good ideas in principle, but the advantages are not huge and cost and complexity are increased, and engine manufacturers are (understandably) resistant to change, unless they can clearly make more money. |
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//Do a search on "Brown's Gas" for great examples of deluded backyard nuclear physicists.// |
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"Brown's gas" is one of the most nauseatingly offensive terms ever. Yull Brown is not necessarily deluded (although many of his followers are); he is a manipulative con artist, with falsified credentials, who steals other peoples ideas and defrauds people of their money. |
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[spidermother]: An exhaust-powered alternator would increase backpressure, increasing the amount of work the engine would have to do by an amount at least equal to the energy it could produce. Did you mean a vacuum-powered alternator (as described in one of my ideas)? |
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I meant exhaust powered. There certainly is energy in exhaust that can be harvested beyond any increased load on the engine; otherwise, the makers of turbochargers (and jet engines) are deluded. |
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Clearly, what's needed is both. There is more vacuum energy available at low throttle, and more exhaust energy available at open throttle. Simply use whichever is most abundant. |
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