Aces High Bulletin Board
General Forums => The O' Club => Topic started by: rabbidrabbit on November 04, 2006, 10:08:10 AM
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http://www.dpccars.com/car-movies/09-25-06page-Air-powered-car.htm
Gee... do you really want a comment? If you watched the video you would know there was no troll except the one who lives under the bridge fragging stuff pointlessly.
There are a couple of youtube shows on how air engines are being developed that might very well change energy use in the US. It looks pretty promising but is it for real?
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I always thought those 'air hog' toys were pretty cool. The concept works, much just like a kit toy stirling engine . Making it useful for much else is a pretty big challenge. I always liked the gas turbine engine cars from the 50's since they could run on about any liquid fuel that would burn and also because that was the engine in the batmobile.
Fwiw, I have precharged pneumatic (PCP) rifle which operates on 3000 psi air. It's fun and almost practical. Originally, the PCP was a British invention.
Regards,
Malta
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what I don't get is how they are as efficient as they seem to be now.
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Originally posted by rabbidrabbit
what I don't get is how they are as efficient as they seem to be now.
You have to understand that it is not in a car like you are used to. It's in a very light stripped down car, and with only one person in it. And it still doesn't have the same performance as even a small low powered economy car like you are accustomed to.
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I'm guessing it all comes down to storing enough compressed air to give something marketable enough range. If you can pull that off it might be efficient enough to work. That being said, is it any better than an electric car?
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Where does the compressed air come from? What creates the power that runs the compressor? Same question the hydrogen car folks need to answer.
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The compressed air comes from captive librules locked in the trunk with masks over their faces and a snapshot of Pres Bush taped in front of them. They just can't help themselves and a steady stream of compressed hot air spews forth. I heard that's why Nash was gone for a while... He was the trunk librule during recent testing, explaining the dramatic increase in compressed air capacity.
:)
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I don't think it would be a very efficient battery. Lots of losses in converting electricity to compressed air. Perhaps not as much as in the case hydrogen fuel-cells
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the question comes down the most cost effective fuel. Just because it runs on compressed air does not mean it will be cheaper per mile. They do seem to be saying that is the case though...
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Originally posted by Chairboy
Where does the compressed air come from? What creates the power that runs the compressor? Same question the hydrogen car folks need to answer.
Getting into the Hydrogen question it means that you're using roughly he same energy as with a combustion engine. However, there are way better means of controlling the pollution in the business.
All cars with hydrogen = same energy used, but no city smog.
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The problems with pneumatic, spring, and flywheel cars are weight vs energy storage, safety, and cost. Also thermal energy (from burning something) has to be converted to electrical energy then mechanical energy to operate a compressor, or wind a spring, or spin a flywheel. That means any of these devices have a lower total efficiency than an electric car. However, that may not make them impractical. Most US appliances have much lower efficiency than their European counterparts but work just fine and are quite practical.
Practicality comes from having something that can do the job safely, inexpensively, simply, and in a wide range of conditions. Practicality stops many things from happening including lead acid battery electric cars. Safety is a significant concern with a compressed gas car and compressed air is (relatively) expensive. Also, air motors (that convert pressurized air to mechanical motion) are not efficient. However, compressed air motors are ideal for some emergency systems.
While the off road remote control air powered toy car is cool, having a massive air compressor to refill the equivalent full size car would not be cool and having a large volume high pressure pressure vessel creates conditions for an explosion. For example, when pressure testing tanks with air or another compressed gas a separate calculation for the equivalent amount of TNT is done. This then gives a blast radius which must be observed.
As most people experience, there is no practical alternative to the modern internal combustion engine. If electric batteries were better for use in cars then electric cars would be used. Currently, batteries and so called "Super capacitors" need improvement and may never be practical due to cost.
It's possible to make a compressed air car, but who wants 5000 psi composite air tanks behind them? Not me. Also as compressed air is used, it cools which may be desired in summer but is unwanted in winter. As technology improves, compressed air cars may become more practical with better air tanks, compressors, and air motors.
The bottom line; compressed air cars are possible, but they are not efficient or practical.
Regards,
Malta
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I think your assertion that the electric car is more efficient than any other is a bit off. Chemical batteries have very low efficiencies, a significant portion of the power is lost to heat. It's possible that flywheel or compressed air would be more efficient than electric, but it depends on the systems in between.
Pure electric=not very efficient.
Internal combustion=not very efficient
The risk of explosion with the tanks is pretty darn low, these prototypes use carbon fiber wound tanks that are much more likely to simply leak than explode.
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Explosion chances would be enhanced by collision.
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This:
"As most people experience, there is no practical alternative to the modern internal combustion engine. If electric batteries were better for use in cars then electric cars would be used. Currently, batteries and so called "Super capacitors" need improvement and may never be practical due to cost.
"
"Practical" is a money question, the money question depending on setups like taxing, resources etc.
Then you're into politics. They and the setup outcome do indeed decide what is in that case "practical" or not.
Som in Brazil, it is practical to use biomass to make ethanol for fuel, - in the USA not so.
In Europe it is getting practical to grow rape for the oil, - the main product being biodiesel, - the byproduct is cattlefood.
But I am still stuck with a combustion engine.
Well, in Iceland by now, we use hydro-powered buses and they're doing just fine ;)
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Originally posted by Angus
Well, in Iceland by now, we use hydro-powered buses and they're doing just fine ;)
I'm sure you realize that hydrogen is just a very inefficient battery. Doesn't matter in Iceland though, as you have an abudancy of free energy. The only advantage a hydrogen car has over an electric car is the lower charging time.
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i still think that 6 stroke design that was posted about 6 months back is very, very promising - if they can get it working with regular tap water.
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Is this gonna be like the biofuels where we have to switch farms from food production to fuel production and we have fuel but no food?
Once you put a value on air we're all screwed.
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One thing's clear, we're going to have to figure SOMETHING out.
That First Law of Thermodynamics is a b*tch, ain't it?
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Originally posted by mora
I'm sure you realize that hydrogen is just a very inefficient battery. Doesn't matter in Iceland though, as you have an abudancy of free energy. The only advantage a hydrogen car has over an electric car is the lower charging time.
AFAIK. Hydrogen production, even from fossile fuels, is as effective in energy economy, as using it directly in a combustion engine.
The pollution is also better to harness.
And as for this:
"Is this gonna be like the biofuels where we have to switch farms from food production to fuel production and we have fuel but no food?
Once you put a value on air we're all screwed"
Well, we had civilization for some 7000 years now. The way we live now, even if it stops where it is, won't even work for 200 years ahead. One day or another the party has to stop.
The fun part is that most of the energy we are using is not just cars, and secondly, mostly for waste. You'd be surprized how much energy gets wasted on dumpings,..,.,......
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I can see how this could work. The carbon fiber storage tanks is a smart way to go. Range is going to be the big problem. Now if they were able to say hook up a small compressor that was linked to the drive wheel, on longer drives where the wheel was turing at a fast rate the compressor would allow the car to recharge the tanks by itself, or at least extend the range before having to fill the air tanks again. All you would need is a clutchable drive belt for the compressor to engage or disengage.
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Originally posted by Hornet33
I can see how this could work. The carbon fiber storage tanks is a smart way to go. Range is going to be the big problem. Now if they were able to say hook up a small compressor that was linked to the drive wheel, on longer drives where the wheel was turing at a fast rate the compressor would allow the car to recharge the tanks by itself, or at least extend the range before having to fill the air tanks again. All you would need is a clutchable drive belt for the compressor to engage or disengage.
No, all you would need to do is violate the laws of thermodynamics.
It wouldn't work, and it would decrease your range.
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Chairboy......SSSHHHHHHH!!
You are disturbing the birth of the perpetual motion machine! :furious :furious
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Originally posted by Chairboy
I think your assertion that the electric car is more efficient than any other is a bit off. Chemical batteries have very low efficiencies, a significant portion of the power is lost to heat. It's possible that flywheel or compressed air would be more efficient than electric, but it depends on the systems in between.
Pure electric=not very efficient.
Internal combustion=not very efficient
The risk of explosion with the tanks is pretty darn low, these prototypes use carbon fiber wound tanks that are much more likely to simply leak than explode.
The basic lead acid battery is about 75-85% efficient. An electric motor is 90+% efficient. Energy from heat has a Carnot efficiency of about 35%. If gasoline or diesel fuel is used, then something burned must be turned into electricity, converted into mechanical motion by an electric motor, then the energy from the electric motor stored in either a spring, compressed air, or kinetic energy (i.e. flywheel). Applying the second law of thermodynamics means spring, compressed air, or KE storage, along with any coupling and transmission efficiencies would have to be greater than 70% to equal the efficiency of an electric powered car using lead acid batteries. Lead acid battery technology is over 100 years old and more efficient batteries now exist.
Any of the above energy storage types can be used independent of petroleum oil and can use coal, solar, or nuclear energy. However, if using petroleum oil, directly burning oil at 30+% efficency is at or near Carnot efficiency. So, for a thermal energy source such as petroleum oil, the internal combustion engine (i.e. the otto cycle or diesel cycle) is a very efficient use of the oil energy. Without oil, all energy needs to be converted to electrical energy for transmission. Converting elecrical energy back to mechanical energy for storage has a cost in efficiency.
The carbon fiber high pressure cylinders are composites, which are lighter weight than fiberglass but still prone to the same types of failures. Carbon fibers aren't a 'magic bullet' and still use an epoxy binder much like fiberglass. Work has been done to embed strain sensors for health monitoring in these tanks but it is still under development. Someday (I doubt in my lifetime) high pressure composite tank rupturing may not be a consideration. Depending on the cost, compressed air cars may become more practical then. However, compressing air to be later expanded for mechanical work will never be as efficient as electrical energy converted to mechanical energy.
Regards,
Malta
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Originally posted by Angus
AFAIK. Hydrogen production, even from fossile fuels, is as effective in energy economy, as using it directly in a combustion engine.
The pollution is also better to harness.
I believe burning hydrogen in an internal combustion engine isn't any more effective than burning up hydrocarbons. Perhaps you could build a working adiabatic(sp?) internal combustion engine running on hydrogen, but I doubt it would happen.
You have to take into account the losses in transportation and converting eletricity into hydrogen. The fuel cells aren't 100% efficient either. The hydrogen also needs to be cooled to keep it in a liquid form. All in all I believe the efficiency of all this would be way below a lithium battery. The only advantage would be the charging time, which would be minutes with hydrogen, and an hour with a lithium battery. Me thinks that electric cars have a better future.
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Originally posted by Angus
AFAIK. Hydrogen production, even from fossile fuels, is as effective in energy economy, as using it directly in a combustion engine.
The pollution is also better to harness.
I believe burning hydrogen in an internal combustion engine isn't any more effective than burning up hydrocarbons. Perhaps you could build a working adiabatic(sp?) internal combustion engine running on hydrogen, but I doubt it would happen.
You have to take into account the losses in transportation and converting eletricity into hydrogen. The fuel cells aren't 100% efficient either. The hydrogen also needs to be cooled to keep it in a liquid form. All in all I believe the efficiency of all this would be way below a lithium battery(or other types of advanced batteries in the future). The only advantage would be the charging time, which would be minutes with hydrogen, and an hour with a lithium battery.
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Originally posted by Vulcan
Is this gonna be like the biofuels where we have to switch farms from food production to fuel production and we have fuel but no food?
Growing fuel is helpful and there is some money in it for some farmers, but to do it on a large scale is just a greenies pipe dream. There's not enough arable land on the planet to make it worth while growing enough fuel in bulk to offset the costs of lower food production.
Originally posted by Vulcan Once you put a value on air we're all screwed.
Speaking at a domestic level, we are well down the path to screwedom as it is. The profitability is being taxed right out of farming by local and central govt i.e. increased production costs, which is hurting our ability to compete in trade.
If things don’t change soon and we are hit with the inevitable "global warming taxes" imo they will either deliver a killer blow or spark a revolt. I'm betting on the latter.
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Originally posted by mora
I believe burning hydrogen in an internal combustion engine isn't any more effective than burning up hydrocarbons. Perhaps you could build a working adiabatic(sp?) internal combustion engine running on hydrogen, but I doubt it would happen.
You have to take into account the losses in transportation and converting eletricity into hydrogen. The fuel cells aren't 100% efficient either. The hydrogen also needs to be cooled to keep it in a liquid form. All in all I believe the efficiency of all this would be way below a lithium battery(or other types of advanced batteries in the future). The only advantage would be the charging time, which would be minutes with hydrogen, and an hour with a lithium battery.
I took my data from news and websites a long time ago and I don't have it handy except in the back of my head. But I recall it was roughly the same output by making Hydrogen and then use it for propulsion (it's not done by combustion) as taking the fuel for a combustion engine. The magic is that only a little part of the fuel we burn in a car engine is effective for propulsion, while electicity generated even by burning fossil fuels is done in a plant which is far more effective than Ms.Daisy driving her car.
So, there are all these ideas around about how to store the energy to get a max output from the engine, such as air, electricity etc, or move to Hydrogen.
But the downside of Hydrogen is there as well. It's bulky, and the engine is bulky. You can use it on a bus, but we're far away from making it practical for personal vehicles.
The trick there would rather be methanol, but again, then you're back into combustion....
My 2 cents is that the solution will not be a single one.
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Need to go back to steam, rebuild the steam or Stirling engine to current standards. Steam engine can be setup to burn virtually any fuel, biomass, etc.
Its just a matter of setting up the firebox and adjusting the fuel/air rate. You could drive to the office on last weeks newspapers. Or throw in a couple of oak logs, or fill a wood pellet hopper for that long trip.
Look at todays modern wood pellet/corn stoves for heating.
It would be very easy to design a steam engine with similar features & safeguards. Multi fuel capability is also easy. You could burn straight vegetable oil without having to refine it or convert it to biodiesel.
Steam Electric hybrid has LOADS of potential, but will it happen in our lifetime?
Don't bet on it, big business is not going to let anything happen that can seriously impact their revenues.
As for Hydrogen, its really only efficient if we use renewable resources to make the power. Solar, wind, tidal all have potential depending on where you live.
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Steam engines are incredibly energy-inefficient.
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Viking, do you include the Sterling cycle in that assessment?
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No, but the Stirling engine does not run on "last week's newspapers". It runs on diesel.
EDIT: Those in current appications run on diesel.
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Sterling cycle runs on anything, it's just heat difference. I've seen sterling cycle setups that run off burning paper.
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You've seen that in a vehicle? How many tons of newspapers would you need to burn to go say 200 miles?
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I've never seen any stirling engines in a vehicle, have you?
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it takes more energy to compress the air , than the energy released.What bussines is that propulsion sistem/? burns fuel/electric energy to compress air,
imop, the future of car propulsion is electric not air, but the goverments have to invest more in research for new sources: hydrogen cell, nuclear physic ,cold fusion
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Originally posted by Chairboy
I've never seen any stirling engines in a vehicle, have you?
Yes, but not in a road vehicle. I've seen it in submarines (Swedish AIP system), and they burn diesel and liquid oxygen.
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bear in mind that most of the energy consumed by your car does NOT go the propulsion bit. AFAIK efficiency is in the 20 - 30% ballpark
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There is always "It"...
(http://www.planearium2.de/pics/pics-511-5.jpg)
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Originally posted by Angus
bear in mind that most of the energy consumed by your car does NOT go the propulsion bit. AFAIK efficiency is in the 20 - 30% ballpark
Yes, and in contrast to a typical steam engine which gets 1 - 8% (including the boiler).
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I would suggest that relative mechanical, electrical, thermal, etc. "efficiency" is not the main idea that should be pursued in the attempt to get a viable alternative to using petro fuels in automobiles and trucks. I think economic feasability is a far more critcal item to work within. If it cannot be done in a manner that is economically comparable to gas / diesel it isn't going to "fly".
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Stirling cycles can achieve almost 40% efficiency, were you lumping them in with piston steam? Like piston steam, a SC can run on anything that burns. Unlike steam, the efficiency is pretty dang good. Added benefit, the colder it is, the better it runs.
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Originally posted by Viking
Yes, and in contrast to a typical steam engine which gets 1 - 8% (including the boiler).
That would be the old boiler steam engine with piston?
How about the vastly superior steam turbine?
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No. The steam-piston engines are in the lower range of 1-8%. Steam turbines are in the upper range. You'll notice that no modern ship uses steam turbines anymore. They're all diesels now - have been for some time.
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By comparison the Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine (ship motor) exceeds 50% thermal efficiency at maximum economy.
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Originally posted by Chairboy
Stirling cycles can achieve almost 40% efficiency, were you lumping them in with piston steam? Like piston steam, a SC can run on anything that burns. Unlike steam, the efficiency is pretty dang good. Added benefit, the colder it is, the better it runs.
No I was not "lumping" them together. Technically a Sterling Cycle is not a steam engine, and while it is efficient it is also impractical for most vehicles.
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I'm interested in the Stirling Cycle as the generator component for a hybrid electric car. Why do you think it's impractical? Seems like a logical fit.
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It seems impractical because of the cyclic rate. Sterling engines have very low rpm and must therefore be quite big to get any appreciable energy from it. The Sterling has good thermal efficiency, but bad power to weight ratio which is important in a small vehicle like a car.
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Why don't cars have Stirling Engines?
http://www.stirlingengine.com/faq/one?scope=public&faq_id=1#3
Keep in mind this is information from a site that sells Stirling engines. They may be biased.
Regards,
Malta
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Originally posted by Viking
By comparison the Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine (ship motor) exceeds 50% thermal efficiency at maximum economy.
Interesting. And this is not THE limit of perfect combustion, although being vastly ahead of a car, - well, it doesn't exactly run the same way as a ship does much of the time.
The "pocket" Battlecruisers had diesels, wonder how that came out in fuel economy vs their Turbine powered brethren.Compare Graf Spee with the Edinburgh class cruisers perhaps, - similar weight AFAIK. There must be numbers around there somewhere.
Then off to generating electrics. What methods are used in the powerplants??? Surely not diesels????
and a P.S. which gives hope to you engine guys:
http://www.tct.is, but sadly in Icelandic. These guys are developing a new generation of carburettors, giving vastly more fuel efficiency, and can be installed on most systems. Here's one for mixing diesel and gas:
(http://www.heima.is/fjolblendir/myndasafn/images/2.26_x600.jpg)
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The car Diesels can achieve 40% efficiency too, and there's room for improvement.
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Yes but Gas & Diesel are non renewable resources, they are finite. They WILL run out at the rate we are using them.
External combustion, ie steam, sterling, etc can burn anything.
Like corn, cornstalks, switch grass pellets, wood pellets made from sawdust, vegetable oil, methane. These are all renewable resources. We can harvest them year after year with no ill effects.
As to the sterling engine, they make them to run off the waste head from your coffee cup. Yes you do get economy of scale with really big ones.
But a moderately sized one sitting there ticking away recharging your battery's in a hybrid makes sense. In summer use a small amount of water & the cooling effect of evaporation to increase performance. That coupled with airflow from the moving car would help boost output. As you noted in colder weather the sterling excels.
As to steam, yes, steam engines developed in the 1800's were pretty inefficient. You don't think we could develop a better system today?
Assuming a high efficiency turbine, just enough power to spin the flywheel and a small alternator/generator for charging battery's. Ok so its not as efficient. It doesn't have to be. With the price of gas going ever higher at some point its going to pay to quit buying gas.
Think of all the garbage every household sends to the landfill every week.
Now, how much of that is burnable, its free, how efficient does it have to be?
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Originally posted by Angus
Interesting. And this is not THE limit of perfect combustion, although being vastly ahead of a car, - well, it doesn't exactly run the same way as a ship does much of the time.
The "pocket" Battlecruisers had diesels, wonder how that came out in fuel economy vs their Turbine powered brethren.Compare Graf Spee with the Edinburgh class cruisers perhaps, - similar weight AFAIK. There must be numbers around there somewhere.
Then off to generating electrics. What methods are used in the powerplants??? Surely not diesels????
I don't know why you want to discuss 60 year old ship engines in a thread about "the future of car engines". Seems quite irrelevant. And I don't follow you on the question of "generating electrics". Do you mean if they use diesel generators on ships? If so then the answer is yes.
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Originally posted by Ghosth
Yes but Gas & Diesel are non renewable resources, they are finite. They WILL run out at the rate we are using them.
Petroleum oil is not a finite resource. New oil is formed every day, but at a much slower pace that we consume it of course. However this is not a problem since every gasoline engine can run on alcohol with little or no modification and every diesel engine can run on bio-diesel with no modification at all. The diesel I buy for my truck is 20% bio-diesel. The EU has decreed that by 2010 50% of the diesel we buy at the pump must be bio-diesel.
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Originally posted by Viking
However this is not a problem since every gasoline engine can run on alcohol with little or no modification
Check your facts there. Alcohol burns much hotter than gas.
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Originally posted by Viking
I don't know why you want to discuss 60 year old ship engines in a thread about "the future of car engines". Seems quite irrelevant. And I don't follow you on the question of "generating electrics". Do you mean if they use diesel generators on ships? If so then the answer is yes.
You're not getting what I mean, or more politely I did nor promote what I wanted to say in the clearest way.
Firstly, the diesel engines in ww2 vs the turbines used to propel vessels about the same size do indeed give something to ponder about.
Secondly, - as for the link with the future, - many methods were tried, tested, produced andd used in WW2 engine technology, only to appear as a "novelty" in our cars 30 or 40 years later.
As for the electrics, I am referring to powerplants and not ships. Land based powerplants where fossil fuel is being burned to generate electricity, - and perhaps as a sideproduct using the heat. I have no idea about their exact efficiency, but I know they are vastly ahead of everyday's Mary in her car.
I know they have diesel Generators on ships, and they did indeed as well 60 years ago. But that's ... Ships. You have limited space and weight, as well as a simplicity factor in the case of failiure. But what do the real powerplants use????
At least there you have a target figure from where to work.
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Originally posted by mentalguy
Check your facts there. Alcohol burns much hotter than gas.
So what?
All gasoline engines can run on a mix of gas and alcohol. With modifications they can run on pure alcohol as many cars in Brazil do. Alcohol has also been used as a racing fuel for decades since it has a natural octane rating of more than 120.
(http://upload.wikimedia.org/wikipedia/commons/thumb/9/93/Alcohol_fuel_pump_in_Brazil.jpg/800px-Alcohol_fuel_pump_in_Brazil.jpg)
A typical gas station in Brazil.
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Originally posted by Viking
So what?
All gasoline engines can run on a mix of gas and alcohol. With modifications they can run on pure alcohol as many cars in Brazil do. Alcohol has also been used as a racing fuel for decades since it has a natural octane rating of more than 120.
(http://upload.wikimedia.org/wikipedia/commons/thumb/9/93/Alcohol_fuel_pump_in_Brazil.jpg/800px-Alcohol_fuel_pump_in_Brazil.jpg)
A typical gas station in Brazil.
Nice :aok
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Originally posted by Angus
You're not getting what I mean, or more politely I did nor promote what I wanted to say in the clearest way.
Obviously. :)
Originally posted by Angus
Firstly, the diesel engines in ww2 vs the turbines used to propel vessels about the same size do indeed give something to ponder about.
Why? What? Please tell me, I don't like guessing.
Originally posted by Angus
Secondly, - as for the link with the future, - many methods were tried, tested, produced andd used in WW2 engine technology, only to appear as a "novelty" in our cars 30 or 40 years later.
Yes, but the technology was unreliable in WWII. For example the DB 600 series of engines had fuel injection. Cars only started to get fuel injection in the '70s. However the DB was a 160 hour engine, try selling a car that needs an engine overhaul every 160 hours. ;)
Originally posted by Angus
As for the electrics, I am referring to powerplants and not ships. Land based powerplants where fossil fuel is being burned to generate electricity, - and perhaps as a sideproduct using the heat. I have no idea about their exact efficiency, but I know they are vastly ahead of everyday's Mary in her car
Modern fossil burning power plants run on natural gas. They use a gas-turbine and a steam-turbine. The gas-turbine (jet engine) runs a generator, and the heat from the jet exhaust is used to power the steam-turbine. Using this combined cycle method they can achieve a thermal efficiency of about 60%.
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Originally posted by Viking
Steam engines are incredibly energy-inefficient.
(http://www.industcards.com/Duernrohr.jpg)
This steam engine exceeds 40% heat efficiency. Double the efficiency of a typical automotive IC engine.
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Originally posted by Viking
No. The steam-piston engines are in the lower range of 1-8%. Steam turbines are in the upper range. You'll notice that no modern ship uses steam turbines anymore. They're all diesels now - have been for some time.
(http://www.marinekameradschaft-muenchen.de/Bilder/neu5-bush-07-truman.jpg)
A steam ship in the US Navy...
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Originally posted by Holden McGroin
(http://www.marinekameradschaft-muenchen.de/Bilder/neu5-bush-07-truman.jpg)
A steam ship in the US Navy...
I thougt they were nuclear
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Originally posted by mentalguy
I thougt they were nuclear
Only the ones that use it to generate steam. ;)
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Originally posted by mentalguy
I thougt they were nuclear
The nuclear power used on ships and nuclear power plant is still on improvement of the Steam engine, it first used coal, liquid fuel and now the nuclear fussion, to warm up water and make steams,
But still steams under presure are the "transit agent", to turbine /prop or turbine/generator and electric power to prop
works same way in Aircraft Carier/ Subs or any other Nuclear powerstation
See the animation below :
http://science.howstuffworks.com/nuclear-power.htm (http://science.howstuffworks.com/nuclear-power.htm)
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Originally posted by Ghosth
Yes but Gas & Diesel are non renewable resources, they are finite. They WILL run out at the rate we are using them.
you can use renewable resources if you want to, Diesels are especially flexible in this regard.
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Viking:
"Yes, but the technology was unreliable in WWII. For example the DB 600 series of engines had fuel injection. Cars only started to get fuel injection in the '70s. However the DB was a 160 hour engine, try selling a car that needs an engine overhaul every 160 hours. "
AFAIK that was not related to the injection.
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More for you to ponder Viking.
Graf Spee vs British heavy cruisers, taking HMS Exeter for there I have both range and fuel. Although Exeter is only some 65% of Graf Spees displacement, one must bear in mind that it's a much older ship.
Graf Spee:
Displacement: 12100-16200 t.
Engines 65.000 hp diesel.
Top Speed: 28.5 kts.
Fuel 2523 t.
Range: 8,900 nautical miles at 20 knots (16,500 km at 37 km/h)
or 19,000 nautical miles at 10 knots (35,000 km at 18.5 km/h)
So you have some 3.5 nm per tonne at 20 kts or some 7.5 Nm per tonne at 10 kts.
Exeter:
Displacement: 8,390t standard; 10,490 deep load
Engines 80.000 hp steam turbine
Top speed 32 kts
Oil 1900 t.
Range: 8,400nm at 14kts
So you have some 4.4 nm per tonne at 14 kts.
As seen, the Diesel holds the cards, just not by very far. I wish I had data handy on the bigger English cruisers, but there seem to be numbers failing all the time. Well, will see what I find.
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Yet to the boiling room, BINGO.
The HMS Belfast and Edinburgh are built close in time to the Graf Spee, and are very close in size, full somewhat above 13.000 tonnes.
82000 hp turbine propulsion to give 32.5 kts, 9800 nm done at 15 kts, and the tanks are holding 2375 tonnes, that makes 4.1 Nm for the Tonne.
Something to extrapolate from for the size. Anyway, seems to me it's pretty much in the same ballpark, but I have no idea what the British cruisers could have gone far in slower cruise. Maybe not a good idea because of Subs...
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Originally posted by Angus
(http://upload.wikimedia.org/wikipedia/commons/thumb/9/93/Alcohol_fuel_pump_in_Brazil.jpg/800px-Alcohol_fuel_pump_in_Brazil.jpg)
Nice :aok
So that's why no finns came out alive from Brass gas stations - they thought the other one was for the car, the other for the driver. :rolleyes:
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Originally posted by Holden McGroin
(http://www.industcards.com/Duernrohr.jpg)
This steam engine exceeds 40% heat efficiency. Double the efficiency of a typical automotive IC engine.
Perhaps double the efficiency of a typical US car engine, but 40% is about 5% less than that of a typical modern small European turbo-diesel.
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Originally posted by Angus
More for you to ponder Viking.
Graf Spee vs British heavy cruisers, taking HMS Exeter for there I have both range and fuel. Although Exeter is only some 65% of Graf Spees displacement, one must bear in mind that it's a much older ship.
Graf Spee:
Displacement: 12100-16200 t.
Engines 65.000 hp diesel.
Top Speed: 28.5 kts.
Fuel 2523 t.
Range: 8,900 nautical miles at 20 knots (16,500 km at 37 km/h)
or 19,000 nautical miles at 10 knots (35,000 km at 18.5 km/h)
So you have some 3.5 nm per tonne at 20 kts or some 7.5 Nm per tonne at 10 kts.
Exeter:
Displacement: 8,390t standard; 10,490 deep load
Engines 80.000 hp steam turbine
Top speed 32 kts
Oil 1900 t.
Range: 8,400nm at 14kts
So you have some 4.4 nm per tonne at 14 kts.
As seen, the Diesel holds the cards, just not by very far. I wish I had data handy on the bigger English cruisers, but there seem to be numbers failing all the time. Well, will see what I find.
Seems like the diesels were about 20-30% more fuel efficient than the steam engines in WWII. However, the diesel's main advantage was probably size back then. Diesels were a relatively new technology while the steam engine was refined over a century of use.
Today the diesel engine has been the most used ship engine for 30 years. There are still a hundred or so steam turbine dinosaurs in operation though. The diesel is smaller, lighter, and more economical while using the same fuel oil. Though combo to beat.
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Originally posted by Holden McGroin
(http://www.marinekameradschaft-muenchen.de/Bilder/neu5-bush-07-truman.jpg)
A steam ship in the US Navy...
Nuclear powered steam turbines are actually even less efficient than conventional steam turbines, both in thermal efficiency and fuel economy. That matters not for military applications of course, but for civilian use they are pointless.
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Less efficient by what measure?
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Originally posted by Viking
Perhaps double the efficiency of a typical US car engine, but 40% is about 5% less than that of a typical modern small European turbo-diesel.
Back in school we calculated the average efficiency of an american V8 gasoline engine with an automatic transmission. It was around 13% IIRC. Now take a small TD engine and couple it with a hybrid powertrain and you have that same car with a fuel consumption of 1/3 of the V8 model.
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Viking:
"Seems like the diesels were about 20-30% more fuel efficient than the steam engines in WWII. However, the diesel's main advantage was probably size back then. Diesels were a relatively new technology while the steam engine was refined over a century of use."
Not really?
Firstly, the fuel consumption is really in the same ballpark. Did you graph this? There is the increased displacement to add to the equation, but also that while the Graf Spee class has a high cruise vs lowe max speed, it can be because of the engines being built for that job, while the boiler cruisers were built for top speed. Just my cents.
Secondly, the diesel was rather older than a steam TURBINE. The steam turbine emerged when? Around WWI?
Then to the Nuclear part. Aren't turbines the only way to harness their energy?
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Originally posted by Chairboy
Less efficient by what measure?
Nuclear vs. Conventional Marine Power Plants
By Al Minyard
Updated 23 December 1998
--------------------------------------------------------------------------------
There appears to be some confusion as to the differences and similarities between conventional steam propulsion plants and nuclear steam propulsion plants. This post is intended to clarify some of the issues. Nuclear propulsion technology is subject to a high level of classification, so some
information must be omitted.
There are more similarities than differences between the two predominate methods of steam ship propulsion, so I will first list these similarities:
1. Both nuclear and conventional propulsion plants use (with a few experimental exceptions) geared steam turbines. These turbine/reduction gear sets are connected directly to the forward end of the propeller shaft, thus one turbine set drives one propeller.
2. Both nuclear and conventional plants use seawater as the primary coolant in the steam cycle (that is, sea water passing through the tubes of a condenser is used to return the used steam to a liquid state so that it can be returned to the steam generator).* Thus the temperature of the near surface sea water can be a limitation on the maximum sustained performance of either type of plant. This typically becomes a serious issue for conventional plants at water temperatures at or greater than
96deg F.
*This is part of the "secondary cooling cycle" in nuclear plants, but it is still the terminal thermal transfer point.
3. Both nuclear and conventional plants use steam turbine powered turbine generators for ship's service electrical power. In warships, and in all nuclear plants, there are diesel (or, rarely, gas turbine) back up generators to power critical circuits.
4. Neither nuclear nor conventional plants develop more power based on the nature of the energy source. Conventional plants are more thermally efficient and tend to last longer than nuclear plants. Nuclear plants operate at lower temperatures and pressures and obviously require fewer refuelings.
5. The limitations on power produced for both types of plants lie in the design and construction of the gears, shafting, thrust bearings, and supporting structure, rather than in the turbines or steam generators.
6. High speed endurance is similar for both plants, until the conventional must slow for a few hours for refueling. The limitations on ship's speed are a product of hull design, propeller efficiency, horsepower, vibration, and thermal build up in the propulsion plant. Nuclear plants do not have a de facto advantage in any of these areas, although the smaller hull made possible by the reduction in liquid load is a factor in some designs.
Some of the significant differences between nuclear and conventional steam propulsion plants are:
1. Cost: Nuclear plants are far more expensive to build, maintain, operate, and dispose of. Fuel costs are actually lower for a conventional plant, considering the costs of a refueling overhaul for a nuclear powered ship. Manning levels are higher for a nuclear plant, as are training costs.
2. Flexibility: Nuclear plants require very heavy and complex foundations and shielding. This has a very significant influence on hull and machinery design. Conventional plants can be configured with many more options.
3. Efficiency: Conventional plants use superheated steam (that is, steam whose temperature is well above the vaporization point at a given pressure). This results in smaller turbine size and greater BTU content per pound of steam. This allows the use of smaller turbines to attain the same power levels. This also eliminates much of the "carry over" of contaminants that can erode and/or foul turbine blades. Nuclear plants use steam that is closer to its saturation point, and this results in greater turbine maintenance requirements.
4. Redundancy: Due to the high cost of reactors, modern nuclear plants are limited to two reactors, while conventional plants for capital ships may have up to eight boilers. The discrepancy in redundancy is obvious.
5. Diplomacy: (Sigh, I really hate this one!) Some "friendly" countries will not allow port visits from nuclear powered vessels. This could be significant in the event of battle damage.
6. Range: Nuclear, no contest.
7. Survivability: The actual survivability of the two designs is similar, with the nuclear plant being somewhat better protected, while the conventional plant is much easier to repair (including "jury rigging" in extremis).
8. The nuclear plant has a smaller above surface IR signature, and possibly a lower radar image, as a result of the elimination of stacks and stack gasses.
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Originally posted by Angus
Viking:
"Seems like the diesels were about 20-30% more fuel efficient than the steam engines in WWII. However, the diesel's main advantage was probably size back then. Diesels were a relatively new technology while the steam engine was refined over a century of use."
Not really?
Firstly, the fuel consumption is really in the same ballpark. (snip)
Your own figures:
Graf Spee:
Displacement: 12100-16200 t.
Fuel 2523 t.
Range: 8,900 nautical miles at 20 knots (16,500 km at 37 km/h)
or 19,000 nautical miles at 10 knots (35,000 km at 18.5 km/h)
HMS Belfast:
Displacement: "somewhat above 13.000 tons"
Fuel 2375 t.
Range: , 9800 nm done at 15 kts
Seems to me that the Graf Spee is almost as efficient at 20 knots as the Belfast is at 15. At 10 knots there is no contest.
Originally posted by Angus
There is the increased displacement to add to the equation, but also that while the Graf Spee class has a high cruise vs lowe max speed, it can be because of the engines being built for that job, while the boiler cruisers were built for top speed. Just my cents.
The Graf Spee and the Belfast are pretty identical in displacement, and a typical steam turbine engine setup allows you to run on only one or two boilers for cruise speeds, so they could vary their efficiency, so top speed is pretty irrelevant. And the difference in top speed is only 3.5 knots anyway.
At 15 knots which is probably the Belfast's best economic cruise speed it is clearly much less efficient than Graf Spee's diesels. I don't see how you can argue the opposite?
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Viking:
"Seems to me that the Graf Spee is almost as efficient at 20 knots as the Belfast is at 15. At 10 knots there is no contest."
Almost but not. At 10 kts we don't have the data from any of the British cruisers. But AFAIK that at the higher speeds the German vessel was more economic, so the tables might actually turn at low speeds. Just another 2 cents.
As for the difference in top speed, you know the drill as with aircraft, you need a lot more energy for increased speeds. The Belfast is what? 15% faster, which would mean a 350 mph aircraft vs a 410 mph one, which is quite a bit. Then you get on to things like acceleration....
Basically:
Belfast/Edinburgh/Exeter have the fuel economy in the same ballpark as the diesels. They have more power and higher top speed. We do not know so much of their lowest speed settings. BTW Belfast has 4 boilers while the other ones have 8.
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Originally posted by Angus
Viking:
"Seems to me that the Graf Spee is almost as efficient at 20 knots as the Belfast is at 15. At 10 knots there is no contest."
Almost but not. At 10 kts we don't have the data from any of the British cruisers. But AFAIK that at the higher speeds the German vessel was more economic, so the tables might actually turn at low speeds. Just another 2 cents.
I highly doubt that. But without real data there is no way to be sure. There is also the question what type of oil did they use. Belfast probably burned no. 6 oil or perhaps no. 4. Did Graf Spee run on diesel oil or heavy fuel oil? All this will vary the results.
Originally posted by Angus
As for the difference in top speed, you know the drill as with aircraft, you need a lot more energy for increased speeds. The Belfast is what? 15% faster, which would mean a 350 mph aircraft vs a 410 mph one, which is quite a bit. Then you get on to things like acceleration....
12%, but top speed is irrelevant. Also 115% of 350 is 402.5, not 410, and the actual number should be 392 (112%).
Originally posted by Angus
Basically:
Belfast/Edinburgh/Exeter have the fuel economy in the same ballpark as the diesels. They have more power and higher top speed. We do not know so much of their lowest speed settings. BTW Belfast has 4 boilers while the other ones have 8.
I disagree, but without more data we're only guessing. Also this it completely off topic, and has no relevance to either modern ship engines or future car engines.
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car engines, the post was about car engines.
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Originally posted by Viking
Nuclear powered steam turbines are actually even less efficient than conventional steam turbines, both in thermal efficiency and fuel economy. That matters not for military applications of course, but for civilian use they are pointless.
All the turbine cares about is that it gets good quality steam and a vacuum in the condenser into which it can exhaust. Steam is steam, and all the turbine cares about is the quality of the steam. It can come from any generating source.
The same turbine design can be used in a nuclear power plant, a coal fired power plant, or in the case of the power station where I work, a combined cycle gas turbine power plant.
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I was talking about marine nuclear reactors vs. conventional stream propulsion, not land based power plants. Land based power plants have little or no restrictions in size or weight. Above I posted Al Minyard's brief to support my view.
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Viking the diesel. You leave me pondering on this:
"--------------------------------------------------------------------------------
Originally posted by Angus
Basically:
Belfast/Edinburgh/Exeter have the fuel economy in the same ballpark as the diesels. They have more power and higher top speed. We do not know so much of their lowest speed settings. BTW Belfast has 4 boilers while the other ones have 8.
--------------------------------------------------------------------------------
I disagree, but without more data we're only guessing. Also this it completely off topic, and has no relevance to either modern ship engines or future car engines."
What do you disagree about? The power and top speed are absolute figures. As a sidenote, the admiral Hipper was turbo powered and as heavy as the Graf Spee, but with more power (some 100.000 hp) and higher top speed as a result.
Do you disagree about the fuel econmy? Well, you can always calculate it into Newtons vs a timeframe to find out the total energy. Either way, there is a vast difference between your promoted 8% vs what, - 20%?
And the off topic I regard as a flank, sorry. The future of car engines is with certainty NOT status quo, so that means any method is going to be used to convert all sorts of fuels mankind has into an appliable energy that can be used to propel a car.
Highly efficient powerplants are a part of that chain, and they seem to use fossil fuel for turbos rather than engine sets. Smaller power plants and backups go to the engine sets, probably for the sake of simplicity.
And HoldenMcGroin, I look forward to you pondering on this ;)
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Originally posted by Angus
What do you disagree about?
The fuel efficiency!
Originally posted by Angus
Do you disagree about the fuel econmy? Well, you can always calculate it into Newtons vs a timeframe to find out the total energy. Either way, there is a vast difference between your promoted 8% vs what, - 20%?
What are you rambling on about now? I've never "promoted" that 60 YEAR OLD diesels were more efficient than steam, but it seems they were. I've argued that MODERN diesel engines are more efficient than steam engines, AND THEY ARE. Where do you get the 20% number from??? I've been against including these WWII ships in this discussion from the beginning, but it is just like you to bring something completely irrelevant into a discussion, jumping from topic to topic and using numbers and math that have no foundation in logic or reason. I'm seriously starting to wonder if you keep doing this simply to piss people off or if you have some attention deficiency. :huh
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yes but Viking your talking Apples & oranges.
Your talking Modern Diesel vs ancient steam.
That was my whole original point. we need a MODERN steam engine.
Preferably turbine, preferably sized for car.
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Originally posted by Ghosth
Your talking Modern Diesel vs ancient steam.
No, I'm talking modern diesel vs. modern steam. "Modern" as in in use today. And I would think they are exclusively steam turbines. However there are very few left, and I would surmise for good reason.
I don't imagine a practical steam engine for car application will ever be used again. I could be wrong of course.
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The discussion about naval engines might be relevent to the thread some day when they put one in a car. :p :rolleyes:
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Originally posted by Viking
The fuel efficiency!
What are you rambling on about now? I've never "promoted" that 60 YEAR OLD diesels were more efficient than steam, but it seems they were. I've argued that MODERN diesel engines are more efficient than steam engines, AND THEY ARE. Where do you get the 20% number from??? I've been against including these WWII ships in this discussion from the beginning, but it is just like you to bring something completely irrelevant into a discussion, jumping from topic to topic and using numbers and math that have no foundation in logic or reason. I'm seriously starting to wonder if you keep doing this simply to piss people off or if you have some attention deficiency. :huh
Call it rambling if it burns your skin, I am basically comparing 70 years+ old British steam TURBINES to some 67 years old German diesel, and adding another german 67 year old Turbine into the equation.
These were the hottest and newest "powerplants" of the day, and since the money and usage put into them was quite a lot we must look into what was learned.
Irrelevant as it is, which it ISN'T, a powerplant is a powerplant - little ones in cars bigger in ships, and very big ones on land.
So, with rambling put aside, please explain why massive rows of combustion engines are not used to generate electricity from fossil fuels on land?
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the induction electric motor is the future, low maintenance, nothing to wear out, only moving parts are the two bearings. and you can eliminate the drive train by putting the motors in the hubs.
only weak point is the need for better batteries, but that is improving every day, DeWalt now has 36 VOLT portable hand tools.
when the people decide they want the simplicity of electricity the cars will be built.
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only weak point is the need for better batteries, but that is improving every day, DeWalt now has 36 VOLT portable hand tools.
They might be 36 volt, but they only provide a bit more power than batteries did 30 years ago. (The higher voltage is just used for marketing, 36 volts does not necessarily provide more power than 12v. The important thing to look at is the wattage)
when the people decide they want the simplicity of electricity the cars will be built.
The problem for electric cars is batteries have a huge way to go to equal the power to weight of gasoline. The best batteries now store about 0.7 megajoules per kg. Gasoline contains about 44 megajoules per kilogram.
What that means is if you want a battery that stores as much energy as a 20 (us) gallon tank, it will weigh about 4.2 tons. (and cost a fortune)
Whilst an electric car is much more efficient than a gasoline one, a battery that provides enough energy to give the same sort of performance that people are used to is just too heavy for a practical car design. And it has other drawbacks, like it takes a long time to charge.
Batteries have got a long way to go before they are practical for normal cars.
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Originally posted by Angus
So, with rambling put aside, please explain why massive rows of combustion engines are not used to generate electricity from fossil fuels on land?
You haven't listened at all; internal combustion engines ARE used to generate electricity on land. An LNG gas turbine IS an internal combustion engine. Secondly, diesel fuel is more expensive than LNG. LNG is now available in Norway as car fuel in city areas and it is popular with bus companies and taxis. The only reason I can think of that prevents LNG from fueling ships is that transporting LNG in such quantities is dangerous. What I predict for the future of car engines is multi-fuel engines based on modern turbo-diesels.
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Originally posted by Viking
You haven't listened at all; internal combustion engines ARE used to generate electricity on land. An LNG gas turbine IS an internal combustion engine. Secondly, diesel fuel is more expensive than LNG. LNG is now available in Norway as car fuel in city areas and it is popular with bus companies and taxis. The only reason I can think of that prevents LNG from fueling ships is that transporting LNG in such quantities is dangerous. What I predict for the future of car engines is multi-fuel engines based on modern turbo-diesels.
Yes? Crankshaft and camshaft With Pistons and valves is what I mean, Not a Turbo. Well I'm stilla bit stuck with the efficiency of powerplants I guess.
As for this:
"The only reason I can think of that prevents LNG from fueling ships is that transporting LNG in such quantities is dangerous. "
I might add something. (Agree with you).
The naval diesel sets are reliable and quite effective. If something is to replace them properly, it should better be good. Even if weight is not the absolute issue as in a car, reliability is a must, or against that, costs.
So, anyway what you said here:
"What I predict for the future of car engines is multi-fuel engines based on modern turbo-diesels."
I pretty much think is right, at least as the next step. Along with Hybrides I guess.
And Nash:
"--------------------------------------------------------------------------------
only weak point is the need for better batteries, but that is improving every day, DeWalt now has 36 VOLT portable hand tools.
--------------------------------------------------------------------------------
They might be 36 volt, but they only provide a bit more power than batteries did 30 years ago. (The higher voltage is just used for marketing, 36 volts does not necessarily provide more power than 12v. The important thing to look at is the wattage)"
30 years ago you did not have tools such as wheel saws powered by rechargable batteries. I am serious, arond here, any carpenter now has the newest DeWalt handtools without a cable, working all day! Bloody incredible stuff. Heck, 30 years? only 5 years ago reality was different!
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Originally posted by Angus
Yes? Crankshaft and camshaft With Pistons and valves is what I mean, Not a Turbo.
(http://www.bowerspower.com/images/xs2000u.jpg)
2000 KW Detroit Diesel Generator
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A nice brushless motor can achieve over 90% efficiency. A good Li-Poly battery is also extremely efficent. Modern chargers and controllers are quite efficient. I believe it's possible to build an 80% efficient electric drive with off-the-shelf components. i.e. 1KWH total input energy to the battery, about .8KWH at the wheel. I think even higher efficiencies are possible with deep pockets.
How you get and transport your energy in the first place is a whole 'nother topic.
Besides, who needs a motor anyways? Check out my company's bike :)
http://www.easyracers.com/videos/NissanOneHourChallengeFinish.mov
http://www.easyracers.com/BM2006/fredhelmetcamqtmovie.mov
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Originally posted by Holden McGroin
(http://www.bowerspower.com/images/xs2000u.jpg)
2000 KW Detroit Diesel Generator
Backup generator? I've seen the one they have for emergency backup in a nearby town, but it's only 1000KW.
Anyway, what do you use for 1MW?
Edit: That sould be 1000 MW ;)
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Originally posted by g00b
A nice brushless motor can achieve over 90% efficiency. A good Li-Poly battery is also extremely efficent. Modern chargers and controllers are quite efficient. I believe it's possible to build an 80% efficient electric drive with off-the-shelf components. i.e. 1KWH total input energy to the battery, about .8KWH at the wheel. I think even higher efficiencies are possible with deep pockets.
How you get and transport your energy in the first place is a whole 'nother topic.
Besides, who needs a motor anyways? Check out my company's bike :)
http://www.easyracers.com/videos/NissanOneHourChallengeFinish.mov
http://www.easyracers.com/BM2006/fredhelmetcamqtmovie.mov
Dude, that is insane...
Was there a tailwind at all? Not that it really matters in the grand scheme of things, b/c a non-paced human being exceeding 60 mph under his/her own power...CRAZY.
Edit: What was the wattage he was producing during that hour?
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Power plant. Thermal one, wonder what the typical efficiency is:
(http://upload.wikimedia.org/wikipedia/en/thumb/f/f1/PowerStation3.svg/800px-PowerStation3.svg.png)
Linkie:
http://en.wikipedia.org/wiki/Power_station
Then the Stirling. Wikipedia sais this:
"The ideal Stirling engine cycle has the same theoretical efficiency as a Carnot heat engine for the same input and output temperatures. The thermodynamic efficiency is higher than steam engines (or even some modern internal combustion and Diesel engines)."
Linkie:
http://en.wikipedia.org/wiki/Stirling_engine
And another:
http://www.howstuffworks.com/stirling-engine.htm
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Originally posted by Angus
Power plant. Thermal one, wonder what the typical efficiency is:
Ours does about just under 50% and it is state of the art circa 2002
(Combined cycle gas turbine/steam turbine)
A good supercritical pressure coal plant is in the mid to high forties.
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That's a far way from 8%.
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8% was typical for a piston steam engine which did not have a condenser.
In 1915, Stanley put condensers on their Steamer automobiles, so the technology is not all that revolutionary.... James Watt patented the condenser in 1760 something and it was the condenser, not the engine itself that made James Watt the father of the steam engine.
The condenser lowers the exhaust temperature to maybe 30C instead of 100C so the Carnot efficiency increases tremendously by that extra 70C cooling.
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Originally posted by Angus
Power plant. Thermal one, wonder what the typical efficiency is:
(http://upload.wikimedia.org/wikipedia/en/thumb/f/f1/PowerStation3.svg/800px-PowerStation3.svg.png)
Linkie:
http://en.wikipedia.org/wiki/Power_station
I bet that power station has similar efficiency as a modern diesel engine, perhaps not quite as efficient though.
HOWEVER … it is easy to get efficiency when you can use thousands of tons of insulation on the boilers and have unlimited space. Try scaling that monster down to something that can be used in a moving vehicle and see how efficient it will be.
That's what we were discussing here remember: Engines, not electric power plants.
Originally posted by Angus
Then the Stirling. Wikipedia sais this:
"The ideal Stirling engine cycle has the same theoretical efficiency as a Carnot heat engine for the same input and output temperatures. The thermodynamic efficiency is higher than steam engines (or even some modern internal combustion and Diesel engines)."
Linkie:
http://en.wikipedia.org/wiki/Stirling_engine
And another:
http://www.howstuffworks.com/stirling-engine.htm
The Stirling was discussed on page one of this thread.
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Originally posted by Angus
(Agree with you).
See, we can agree on something! :)
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Yes, but yet here:
"I bet that power station has similar efficiency as a modern diesel engine, perhaps not quite as efficient though."
Why would a power station not be run by diesels rather than turbos if that was the case??????????
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We run our turbines 24/7 for 11 months and then inspect... We have 24,000+ hours on one of the gas turbines, and it is still producing well. The steamer has been going since start up in 2002.
The same thing happened in the airline industry. Maintenance costs dropped precipitously when they swicthed to turbine engines.
Time Between Overhaul on an aircraft piston engine is 2000 hours (+/-)
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Diesels are very much more stable and last longer. Not sure how long if they are always used on Max performance, but on a typical say tractor engine you have some 10.000 hrs?
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Originally posted by Angus
Yes, but yet here:
"I bet that power station has similar efficiency as a modern diesel engine, perhaps not quite as efficient though."
Why would a power station not be run by diesels rather than turbos if that was the case??????????
Diesel and heavy fuel oil is more expensive than LNG or coal, so even if the diesel engine is more effective it will cost more to run. Also the gas turbine allows for a secondary stream cycle to be run off its exhaust heat increasing the efficiency slightly above that of a pure diesel. The maintenance costs are also obviously less for a turbine, like Holden said.
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Originally posted by kamilyun
Dude, that is insane...
Was there a tailwind at all? Not that it really matters in the grand scheme of things, b/c a non-paced human being exceeding 60 mph under his/her own power...CRAZY.
Edit: What was the wattage he was producing during that hour?
Fast Freddy Markham was puting out about 250 watts for the hour. He covered 53.4 miles from a standing start in one hour (setting the current world record), which means he averaged about 55 mph on 1/3 of a horsepower. A quick conversion shows only about 250 food calories (I suspect more), so about 55 miles on one healthy sandwich or burrito :) He has also gone 77mph top speed, which is currently 3rd fastest in the world.
All of these attempts have less than 3 mph wind and zero slope as required by the governing body, the IHPVA.
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Steam-powered cars used to do quite well against diesels --
0-75mph in 10 secs and a maximum speed of 100mph is pretty good for 1924.
15 mpg of kerosene.
The drawback was the heat-up time: 30-40 secs.
Here's the skinny on the Doble Model E (http://itotd.com/articles/594/doble-steam-cars/).