180Marty wrote:lesuther, here is an email from a friend that designs ethanol plants. They are spending their money to do research to prove the BS you want to believe is wrong.
I'm glad it's still a free country. Chemistry and thermodynamics *are* simply theories, after all...along with those so-called 'laws' of gravitation...
180Marty wrote:The oil companies do not want competition and will do whatever it takes to attain it. How much actual research have you done?
None beyond what any other physicist, chemist, or engineer with an interest has done.
180Marty wrote:I'm guessing the Focus engine I'm getting is retarded quite a bit when the 87 octane is being burned and advanced when E85 is burned. Also, I understand that ethanol expands more that gas when it is burned creating more push when the piston is going down.
As I mentioned in my post, "flex fuel" cars, or cars built specifically to burn alcohol blends, can advance the ignition to the onset of detonation appropriately for the fuel. This slightly increases efficiency while burning alcohol at higher RPM, and almost not at all while turning at very low RPM. This ability is not available to folks flying certificated equipment.
Also as mentioned, blended fuels can be used at higher compression ratios, which boosts their thermal efficiency (which is a big part of the reason behind the efficiency differences of a diesel cycle versus otto cycle engines). For an engine with a compression ratio and timing regime tuned for gasoline, these improvements are not available. Certain variable compression ratio cycles (i.e. some types of Atkinsons, like some variable valve BMW systems) can widely vary the effective compression ratio to capture some of the benefits of higher thermal efficiency. Or you can switch to a diesel cycle, which is a very different ball of wax since it it inherently more thermodynamically efficient with higher compression ratios *and* you don't need to bother with stoichiometric ratios.
Alcohol blend fuels have a higher heat of vaporization. That means the stoichiometric fuel/air mixture is cooler going into the cylinder than for E0 gasoline. This doesn't sound like much, but it is a huge deal. The thermal efficiency of the cycle is a function of the temperature differences of the maximum flame temp, the exhaust gas temp, the ambient temperature the car is driving in, and the intake temp. If you cool the intake charge more, you lose efficiency. It's about 5% right off the top for E10(the induction temp narrows the temp difference by a whopping 5%) . Note I didn't say power- I said efficiency. You have to burn more fuel to make up for this loss. In addition, alcohol has less energy by weight or by volume than E0. You need 1.5 gallons of ethanol to equal the energy in a single gallon of gasoline. If you add alcohol to gasoline, you reduce the chemical energy of the fuel. In fact, you'll need 2% or so more E10 to match the chemical energy of E0. If you add up the induction cooling losses to the chemical deficiencies, you'll end up losing around 7% on mpg. Most modern cars adjust their timing with knock sensors and can recover a few percent mpg, and most cars will see a drop of a few percent mpg. Much older cars will not recover the losses. This is also the case in planes.
Airplane engines simply don't adjust their timing, and they use relatively low compression. They do not recover the efficiency lost from the induction cooling or chemical losses. You are left with lower HP production and lower efficiency. If you prefer, I can point to any number of well-used references to these facts. Plus every car I've used gets lower mpg on ethanol.
180Marty wrote:This is why many who contend a btu is just a btu don’t recognize mileage benefits with ethanol.
To a physicist, chemist, engineer, or a lay person, it really doesn't matter: A Btu is a Btu. It's actually a sort of well-known joke/truism in thermodynamics circles. An Otto cycle engine designed to burn alcohol can achieve a higher thermal efficiency than an Otto cycle engine burning gasoline. That is a fact, *and* the problem- our engines have a fixed compression ratio and ignition timing, so we are left with *less* efficiency and power. A purpose built alcohol engine can wring more out of every Btu of fuel energy. A blended fuel compromise generally can't.
180Marty wrote:Particulate emissions went up when we didn’t increase the amount of aromatics but simply changed the distillation of aromatics. This is what Honda had demonstrated over a year ago and CARB went out of their way to discredit.
Nobody argues that alcohol can help reduce particulates, CO, and unburned hydrocarbons (aromatics included). Alcohol blends have improved air quality all over the nation. Period. The benefits are rather large for E5 in older and newer engines alike. The improvements for E10 are difficult to discern (translation: almost non-existent).More than that- lots of externalities to fix (like compatibility).
180Marty wrote:E30 performed very well. Not that E85 didn’t do good but the fuel flow and additional cooling effect limited some of the emission benefits. This is not due to the fuel as much as OEM’s don’t have to surpass emission requirements, just meet them.
Your friend just repeated the part about induction cooling losses I described above. He is telling you the same thing.
180Marty wrote:I am seeing that the standard EPA procedures to change from fuel to fuel doesn’t allow vehicles to fully adapt, primarily the ignition. Emission control takes priority in short fuel trim and long term fuel trim can take over 40 miles.
Your friend is correct. People wonder why American cars always have lower mpg than the same model in Europe. Part of it is weight- we like to be safer in a wreck in the US. We also like more HP. But emissions is also a big part of the puzzle. You'll know why when you go visit a large eastern European city the moment you step out of the airport. Ignition is important because as you advance the timing to improve high RPM efficiency, you increase NOx emissions (higher flame temps, longer combustion duration=higher efficiency, worse air).
180Marty wrote:We had two of three vehicles get equal mileage with E30 for the heavier of the three drive cycles. Driving habits do matter in all of this.
Your friend just stated that mpg drops with E30 (equal+equal+(less than equal))/3=(<equal mpg). He knows this too, apparently.
Remember that the ethanol lobby has shown that car engines can likely manage to burn more ethanol. This is a far cry from saying we should burn more ethanol. That is likely why the EPA says "who cares". There is no emissions benefit, and compatibility issues abound with high blend alcohols. And as I mentioned before, more alcohol does not mean any less foreign oil from people we'd rather not be dependent on. The oil we don't buy from them to turn into gasoline will be the oil we buy from them to grow our food and ethanol.
