Mileage (mpg) Using Ethanol Seen 20% Higher Than EPA Says - Bloomberg

[Bill USA]

95. your personal brand of logic seems to allow you to assert "A" and "not A" simultaneously.

you say I said that I "countered their claims with the latent heat argument."

.. you mysteriously missed the fact that I first pointed out the higher compression combustion without detonation was possible with ethanol because of its higher octane number. THis was long before I also added that ethanol's higher heat of evaporation helps with compression because it cools the air fuel charge in the combustion chamber (something also mentioned in Cohn etal paper). Notice Heat of evaporation and octane are two different properities..


First, when I provided a link to the Cohn etal paper, you referred to it, contemptuously, as "remedial reading". Now you do not question their findings but state my contentions are wrong. The only problem with your criticism is that my statements are identical to what they assert in their paper. - as well they should be as I am reporting on the findings in the Cohn etal paper.

here's my comment 22
[div class="excerpt" style="border: 1px solid #000000;"]
22. three MIT scientists designed a DI turbocharged engine with ethanol (DI) that gets 25-30% better mpg

than typical ICE on gasoline. But only about 5% of the total fuel usage is ethanol (it is directlly injected into the combustion chamber).

Ethanol injected into the combustion chamber enables higher boost from the turbo - not just because of higher octane rating (~113 vs gasoline's 86-94) but also because of ethanol's higher latent heat of vaporization cools the air-fuel charge in the combustion chamber. This enables higher boost pressures (the higher latent heat counter-acts the heating induced by higher compression).

see: Ford E85 Direct Injection Boosting Study: A Less Expensive Alternative to Diesel

http://www.greencarcongress.com/2009/04/ford-e85di-gasolinepfi-20090426.html#more


Here's a paper by mssrs Cohn, Bromberg and Heywood:

Direct Injection Ethanol Boosted Gasoline Engines: Biofuel Leveraging For Cost Effective Reduction of Oil Dependence and CO2 Emissions

http://www.ethanolboost.com/LFEE-2005-01.pdf



and here's a quote from the paper I referred to by Cohn etal:

Abstract

Ethanol biofuel could play an important role in reducing petroleum consumption by
enabling a substantial increase in the fuel efficiency of gasoline engine vehicles. This
ethanol boosted engine concept uses a small amount ethanol to increase the efficiency of
use of a much larger amount of gasoline by approximately 30%. ...

Page 1

Ethanol biofuel could play an important role in meeting these goals by enabling a
substantial increase in the efficiency of gasoline engines.


A substantial increase in gasoline engine efficiency can potentially be achieved by use of
a strongly turbocharged small engine to match the performance of a much larger engine.
The aggressive turbocharging (or supercharging) provides increased boosting of naturally
aspirated cylinder pressure. The engine thus produces increased torque and power when
needed1. This downsized engine at the loads used in typical urban driving has a higher
efficiency due to its low friction while providing the maximum torque and power
capability of a much larger engine. Engine efficiency can also be increased by use of
higher compression ratio.

~`
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page 3

Ethanol has a high fuel octane number (a blending octane number of 110) 2. Moreover,
appropriate direct injection of ethanol can provide an even larger additional knock
suppression effect due to the substantial air charge cooling resulting from[font size="red"] its high heat of
vaporization[/font].


The large increase in knock resistance and allowed inlet manifold pressure can make
possible a factor of 2 decrease in engine size (e.g. a 4 cylinder engine instead of an 8
cylinder engine) along with a significant increase in compression ratio (for example, from
10 to 12). This type of operation could provide an increase in efficiency of 30% or more.

Mssrs Cohn, Bromberg an Heywood seem to be making a connection between higher combustion pressures enabled by Ethanol's high octane and high heat of evaporation and higher power output allowing downsizing with friction and weight reductions all producing gains in efficiency of operation. Conclusions I accurately characterized in my comments.

Your personal brand of logic seems to allow you to assert "A" and "not A" simultaneously. The rest of us have to be content with conventional logic that does not allow asserting two mutually contradictory propositions at the same time.