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01-11-2008, 05:24 PM
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#11
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The boiling point of platinum is 6917F (3825C). I think it is safe to say that even at the temperature of exhaust, the vapor pressure of platinum approaches zero.
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01-11-2008, 06:49 PM
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#12
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Join Date: Jan 2006
Posts: 2,444
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Location: Tiverton, RI
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Usually it is some compound of platinum that is mixed with the air / fuel and acts as a catalyst to make th efuel burn better. There was some gas additive many many years ago I saw in a Walmart but never thought the price of it was worth the savings. This unit could be bubbling air through a solution and adding a few molecules of platinum to the a/f mixture.
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01-13-2008, 05:38 AM
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#13
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But here's something else to consider. A modern, fuel injected engine burns pretty close to 100% of the fuel anyway. Even if you are getting 1000ppm of hydrocarbons in the exhaust stream before the cat (which is ALOT), there just isn't enough unburned potential in the exhaust to make a 22% difference in the amount of energy you can get from the gas that an engine consumes.
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01-13-2008, 08:51 AM
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#14
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Location: Tiverton, RI
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THAT IS the question apparently the engine only converts about 25% of the available energy from the fuel . . . now is it because it is not completely burnt or is it because the engine is not capable of utilizing the heat of combustion fully. Should we be looking at ways to improve the combustion chamber efficiency?
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01-13-2008, 09:36 AM
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#15
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Join Date: Mar 2007
Posts: 1,546
Country: United States
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egnines arent the most efficent form of convertign energy(all they are are energy conversion machines, tuns fuel into rotational energy) anytime one thing gets "converted" into another especially getting converted into mechanical energy, theres extremem ammounts of losses.
yes modern engines are much better at burning all the fuel, ever smell an old carburated cars exhaust compared to a new one that just smells like water vapor? reason ebing is that modern engines have on the fly adjustment of A/F raio, timing, temperature compensation, etc. also i know on my truck the spark plugs fire twice during the 4 strokes, ones in the power stroke and the other is somewhere in there to burn what fuel is left if any.
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01-13-2008, 11:33 AM
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#16
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Registered Member
Join Date: Nov 2007
Posts: 321
Country: United States
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Perhaps it's the HEAT we should be conserving or finding use for. The longer the engine retains heat, less MPG's are lost to warm up time. I've found my water temps stay above 100 degrees for 2 hours or more (where It would have been totally cooled off before all the modifications).
The only way I know to improve combustion chamber efficiency is to use the lighter oils; other than converting belt driven components to electrical ( easier said than done).
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01-13-2008, 04:29 PM
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#17
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Posts: 298
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Quote:
Originally Posted by JanGeo
THAT IS the question apparently the engine only converts about 25% of the available energy from the fuel . . . now is it because it is not completely burnt or is it because the engine is not capable of utilizing the heat of combustion fully. Should we be looking at ways to improve the combustion chamber efficiency?
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Actually, the problem is the latter. It is really not that hard to burn almost all of the fuel. Modern, four valve, fuel injected engines actually do that quite well. But just because it is all burned does not mean that all the hat is actually utilized. Remember that we are up against the second law of thermodynamics here. AND you have other thermal and frictional losses as well. So I guess the best way to put it is that the completeness of burning is not the REAL problem.
I should also mention that this is a BIG reason for the push for fuel cells. Fuel cells convert the chemical energy in fuel directly to electrical power. And, for this reason, they are not subject to the second law of thermodynamics in the same way that a heat engine is. Of course, there will ALWAYS be losses. But even so, fuel cells are typically MUCH more efficient than your typical engine is today. And the fact of the matter is the internal combustion engine really does not have much (if any) potential left for greatly improved efficiency.
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01-13-2008, 05:24 PM
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#18
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Registered Member
Join Date: Jan 2006
Posts: 2,444
Country: United States
Location: Tiverton, RI
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Actually the fuel cell is about 60-66% efficient, does rather quickly wear out, is expensive to manufacture, and from the HydrogenOxygen group they seem to think that if an engine designed to burn hydrogen directly was built it would be even more efficient than the fuel cell and a lot smaller for the same horse power of a conventional ICE engine.
http://autos.groups.yahoo.com/group/HyOx/
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01-13-2008, 09:28 PM
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#19
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Registered Member
Join Date: Oct 2007
Posts: 298
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A couple of things about efficiency. First off, what I meant is that fuel cells are not hobbled by Carnot efficiency like heat engines are. This does NOT mean that all fuel cells will be 100% efficient. There will ALWAYS be losses. Rather what I meant is that, even if current cells are 'only' 60-6% efficient, they can be MUCH more efficient in the future.
Then again, 60-66% efficiency is WELL beyond that which is attainable with a conventional ICE. This is important, considering that fuel cells in their infancy are at least TWICE as efficient as the technologically mature conventional ICE. I don't care what kind of fuel you try to burn in an ICE, you are NOT going to get 60-66% efficiency out of it. Even if you built a high efficiency gas turbine, you are probaby not going to do much better than 50%. And, as I said, the fuel used matters little when it comes to efficiency. As for the size of the powerplant, you could probably get it smaller than a fuel cell - at least at this time. But hopefully, future developments will be able to deal with the size and longevity problems of fuel cells.
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01-14-2008, 07:22 AM
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#20
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Registered Member
Join Date: Jan 2006
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Location: Tiverton, RI
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Actually some company just developed a gas turbine electric power system that raised the efficiency to over 60 % don't remember the exact numbers but they recirculated the hot gasses withing the turbine and end up venting only 300 degree exhaust and when used to provide heating raised the total efficiency to over 90%.
The problem of the fuel cell still is that it does produce heat at high power levels and then you still have to power an electric motor which has further losses. A LiIon battery turns out to be a lot more efficient at returning the energy used to charge it and now that AltairNano is producing batteries that can be charged in 10 minutes and last 25 year with 10 of thousands of full charge discharge cycles the whole fuel cell avenue is moot.
I also think they can use the EEStor super ultra caps to store grid energy at charging stations and then dump charge the electric vehicle batteries quickly thus reducing the peak demand on the grid power. You could be slowly charging up the Caps all day off of wind and solar and dump charge the car when you need a quick fill up right at home.
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