The Future of Cars

[82mm 4g63]

Originally Posted by Allch Chcar

That engine wasn't Ethanol only but it did run better on a Ethanol Blends.



The omnivore was a good concept but I see more merit for turbocharged engines with high Static compression. They would run efficient on Gasoline during partial loads but they trade some power and efficiency at moderate to heavy loads. And then run at full power and efficiency with E85 or even a midgrade like the Ricardo engine.

I still see Ethanol as the power with efficiency option unless they start making Ethanol fueled Diesel engines in the US.

And 82mm 4g63, please stop calling the MPG loss efficiency loss. That word you keep using, it doesn't mean what you think it means.

The omnivore engine?

My last reply was literally quoted verbatim from what the experts are saying, I guess you should take their use of the word efficiency up with them? lol

[Allch Chcar]

Originally Posted by 82mm 4g63

The omnivore engine?

You missed the part where I was quoting cerealkilla.

Originally Posted by 82mm 4g63

My last reply was literally quoted verbatim from what the experts are saying, I guess you should take their use of the word efficiency up with them? lol

Actually you did, you used it here:

Originally Posted by 82mm 4g63

Current flexfuel engines absolutely pay an efficiency penalty because they are optimized to use gasoline.

Then you went on to quote the article.

And I am saying that statement is false. The "penalty" is the difference in energy density not some penalty for being inefficient because it was a Gasoline designed engine. The efficiency is the same for E85 and Gasoline in a FFV, the difference is MPG which is a measure of fuel efficiency not engine efficiency. Does it makes sense what I am saying?

[82mm 4g63]

Originally Posted by Allch Chcar

You missed the part where I was quoting cerealkilla.

No, I didn't, I was making sure you were referring to the Omnivore and not the Ricardo engine.

Originally Posted by Allch Chcar

Actually you did, you used it here:

Again, I quoted the experts. Not my words, but Rod Beazley's of Ricardo.

"So-called flex-fuel engines use a mixture of fuels, the most common combination being around 15 percent gasoline and 85 percent ethanol. But these [Flex Fuel] engines tend to pay a 30 percent efficiency penalty because they are optimized to use gasoline, says Rod Beazley, product group director for gasoline at the engineering-research firm Ricardo, based in Detroit."

-http://www.technologyreview.com/energy/22198/

Originally Posted by Allch Chcar

And I am saying that statement is false. The "penalty" is the difference in energy density not some penalty for being inefficient because it was a Gasoline designed engine. The efficiency is the same for E85 and Gasoline in a FFV, the difference is MPG which is a measure of fuel efficiency not engine efficiency. Does it makes sense what I am saying?

Yes, ethanol has a natural handicap because of it's energy density, I'm not arguing that it doesn't. What I'm saying(from the information I've gathered in these articles that I've read) is an engine running on ethanol(or an ethanol blend) designed and limited by gasoline's handicaps is NOT as efficient as an engine running on ethanol(or an ethanol blend) designed to utilize ethanol's unique characteristics.

[Allch Chcar]

Originally Posted by 82mm 4g63

No, I didn't, I was making sure you were referring to the Omnivore and not the Ricardo engine.



Again, I quoted the experts. Not my words, but Rod Beazley's of Ricardo.

"So-called flex-fuel engines use a mixture of fuels, the most common combination being around 15 percent gasoline and 85 percent ethanol. But these [Flex Fuel] engines tend to pay a 30 percent efficiency penalty because they are optimized to use gasoline, says Rod Beazley, product group director for gasoline at the engineering-research firm Ricardo, based in Detroit."

-http://www.technologyreview.com/energy/22198/



Yes, ethanol has a natural handicap because of it's energy density, I'm not arguing that it doesn't. What I'm saying(from the information I've gathered in these articles that I've read) is an engine running on ethanol(or an ethanol blend) designed and limited by gasoline's handicaps is NOT as efficient as an engine running on ethanol(or an ethanol blend) designed to utilize ethanol's unique characteristics.

okay okay. Thanks for clearing that up, my mistake. It just annoys me to no end to hear people say that .

[serialk11r]

I don't think 30% is a typical figure, at least for peak efficiency. Even for off peak efficiency I don't think 30% is accurate. Every naturally aspirated engine these days is at least 10.0:1 compression. If you consider the simplified thermodynamics of the gasoline engine, there's not really a whole lot of room for improvement there. Optimized spark timing sure but I think at lower speeds this is not really an issue.

If it's direct injected, the latent heat of vaporization will slightly increase efficiency by reducing the temperature and compression stroke energy requirement. If it's turbocharged there's probably a bit more help because you can really bump up the compression there. I just don't see 30% really in almost any circumstance, maybe except very low throttle conditions where the effective expansion ratio is very low.

[Allch Chcar]

Originally Posted by serialk11r

I don't think 30% is a typical figure, at least for peak efficiency. Even for off peak efficiency I don't think 30% is accurate. Every naturally aspirated engine these days is at least 10.0:1 compression. If you consider the simplified thermodynamics of the gasoline engine, there's not really a whole lot of room for improvement there. Optimized spark timing sure but I think at lower speeds this is not really an issue.

If it's direct injected, the latent heat of vaporization will slightly increase efficiency by reducing the temperature and compression stroke energy requirement. If it's turbocharged there's probably a bit more help because you can really bump up the compression there. I just don't see 30% really in almost any circumstance, maybe except very low throttle conditions where the effective expansion ratio is very low.

Cerealkilla the 30% "efficiency loss" is from the lower density. E85 has about 70% of the BTUs of a gallon of Gasoline. It changes with the seasons as they adjust the blend rates too.

They don't mean that the thermodynamic efficiency changed at all... hence why I was so harsh on the 30% efficiency loss statement, essentially it is incorrect and it will confuse people unless you are very clear that you are discussing fuel efficiency not energy efficiency.

[serialk11r]

I don't know if we're reading it differently, but I'm reading his quote as a 30% thermodynamic efficiency loss. (silly because their numbers say 20ish at the most, if you compare the highest mpg blend to any other blend) That is like saying, engines could be hitting 133% of current efficiency, which is total bs. Max thermal efficiency of a good Atkinson cycle engine these days is almost 40%. If your compression ratio approached infinity you could not add 30% to that to make it 50%, there simply is not that much loss to recuperate. On that topic, with all these pumping loss reduction techniques, I wonder how they're going to further improve efficiency. Anyone know how much frictional loss usually is?

[Allch Chcar]

It's definitively the MPG loss. I have plenty of tech document links that show thermodynamic efficiency to be very similar(<5% difference) to regular gasoline for mid blends of Ethanol and they get better the higher the blend. The difference gets larger the higher compression ratio, from what I've seen.

The thermodynamic efficiency is similar in FFVs for E85 and Gasoline, it's the MPG that is vastly different.

[Dimman]

Allch Chcar: Have you heard about whether or not E85 will spool a turbo faster? I heard something about that because there is more fuel being burned so the exhaust is heavier, so it has more energy when it hits the turbine.

Any truth to this?

[Allch Chcar]

Originally Posted by Dimman

Allch Chcar: Have you heard about whether or not E85 will spool a turbo faster? I heard something about that because there is more fuel being burned so the exhaust is heavier, so it has more energy when it hits the turbine.

Any truth to this?

I have heard about it, but I don't know, sorry. I've been reading about it like crazy while I save up for a project car. I don't have any experience with tuning .

[serialk11r]

I think that would be dependent on how much residual pressure there is in the cylinder. Since ethanol has different heat of combustion you'd probably need to actually test it to see. However we can do a quick check of the ratio of gas molecules in ethanol vs gasoline.
Ethanol burning:
C2H5OH + 3 O2 -> 2 CO2 + 3H2O
Gasoline (assuming an isotrope of octane)
2C8H14 + 23 O2 -> 16 CO2 + 14 H2O

I hope I got that right. Anyways, we see for each mole of oxygen we are making 30/23 moles of exhaust gas, with gasoline. With ethanol, we are making 5/3 moles of exhaust gas for each mole of oxygen, which is a little more. Ethanol's standard enthalpy of combustion is 1371 kJ/mol, with 3 moles of oxygen. Octane has standard enthalpy of comubstion of 5074 kJ/mol, using 11.5 mol of oxygen. This means gasoline produces approximately 441kJ/mol oxygen, while ethanol produces 457kJ/mol oxygen. However ethanol's slightly greater amount of combustion heat is probably offset somewhat by the greater heat of vaporization, but we can see that the behavior of the 2 fuels is somewhat similar. Since ethanol is producing a slightly greater amount of exhaust gas (5/3=~1.667, 30/23=~1.305), it probably would spool a turbo a bit faster. However most of the exhaust is still nitrogen, so the advantage isn't as big as the difference between those 2 ratios. But it does seem like burning ethanol does produce slightly more combustion pressure because of this

Speaking of which, methanol looks like one kickass performance fuel, it has HUGE latent heat of vaporization :O 35kJ/mol vs. 38 for ethanol, but you need twice as much to burn the same amount of oxygen. Dayum.

[serialk11r]

Actually I apologize that's probably not true, since the heat of combustion is about the same the pressure is supposed to be the same...yea I'm not sure it makes a difference. Actually it's hard to say, the pressure in the cylinders can get pretty high, but the composition of the exhaust is mostly the same so it's probably not a big difference.

But okay holy crap I just realized methanol is pretty insane stuff, my mind is being blown right now.

[Dimman]

Originally Posted by serialk11r

I think that would be dependent on how much residual pressure there is in the cylinder. Since ethanol has different heat of combustion you'd probably need to actually test it to see. However we can do a quick check of the ratio of gas molecules in ethanol vs gasoline.
Ethanol burning:
C2H5OH + 3 O2 -> 2 CO2 + 3H2O
Gasoline (assuming an isotrope of octane)
2C8H14 + 23 O2 -> 16 CO2 + 14 H2O

I hope I got that right. Anyways, we see for each mole of oxygen we are making 30/23 moles of exhaust gas, with gasoline. With ethanol, we are making 5/3 moles of exhaust gas for each mole of oxygen, which is a little more. Ethanol's standard enthalpy of combustion is 1371 kJ/mol, with 3 moles of oxygen. Octane has standard enthalpy of comubstion of 5074 kJ/mol, using 11.5 mol of oxygen. This means gasoline produces approximately 441kJ/mol oxygen, while ethanol produces 457kJ/mol oxygen. However ethanol's slightly greater amount of combustion heat is probably offset somewhat by the greater heat of vaporization, but we can see that the behavior of the 2 fuels is somewhat similar. Since ethanol is producing a slightly greater amount of exhaust gas (5/3=~1.667, 30/23=~1.305), it probably would spool a turbo a bit faster. However most of the exhaust is still nitrogen, so the advantage isn't as big as the difference between those 2 ratios. But it does seem like burning ethanol does produce slightly more combustion pressure because of this

Speaking of which, methanol looks like one kickass performance fuel, it has HUGE latent heat of vaporization :O 35kJ/mol vs. 38 for ethanol, but you need twice as much to burn the same amount of oxygen. Dayum.

It is. How does it work, again? Something like it has 60% the energy but makes peak power with twice the fuel/air, so it can make 120% the power? Something like that? (numbers are just representative...)

[serialk11r]

Crap I typed a bunch of calculations and lost it all somehow. :mad:

Okay so you need twice as much methanol as ethanol to get stoichiometric. Okay so after factoring in the fact that we burn gaseous fuel in engines, methanol comes out to make about 750kJ/mol, 1500kJ/2mol. Ethanol makes about 1370kJ/2mol. The greater cooling effect (32kJ/mol approximately) helps make more power by reducing the work on the compression stroke. At full throttle there's going to be waste pressure anyways, thus the cooling effect isn't actually taking much away from the amount of energy we can get. So methanol looks like it makes about 10% probably a little less more power than ethanol, which looks like it makes about the same power as gas. Good stuff.