HLS wrote:
>
> "Tegger" <tegger@[EMAIL PROTECTED]
> wrote in message
> >
> > Then MTBE is about twice as efficient as ethanol, so the mixture can
be
> > leaner?
> >
> >
> > --
> > Tegger
>
> "Lean", to me, indicates a mixture which does not have an excess of
fuel,
> or may
> even have an excess of the oxidant.
>
> It requires more oxygen to burn a unit amount of MTBE than it does to
burn
> the same unit amount of ethanol, and the energy released is consequently
> greater.
Not according to the EPA. They say it contains less energy than ethanol
per gallon. Density might be different but doesn't matter - no one
purchases liquid fuel by weight.
>
> Most of the energy is derived from the oxidation of the hydrogen atoms
in a
> hydrocarbon
> to form water. Less energy is derived from oxidation of the carbon to
give
> CO2.
>
> The oxygen (in oxygenates such as alcohol and MTBE) just occupies space
and
> doesnt
> contribute to the energy derived from combustion. So, since the ethanol
has
> a higher percentage of oxygen in the molecule, it has a lower amount of
> energy that it can contribute
> upon combustion.
>
> The "octane rating" takes into account different properties of the fuel,
not
> directly related to
> the stoichiometry.
But octane is far more im****tant to fuel economy and performance. That is
more im****tant to how much energy goes to the wheels.
According to the EPA Ethanol and MTBE are almost the same for oxygen
content, octane and energy content. According to the EPA it takes 10
percent ethanol to get the same oxygen as 11 percent MTBE.
-Jim
----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet
News==----
http://www.pronews.com
The #1 Newsgroup Service in the World! >100,000
Newsgroups
---= - Total Privacy via Encryption =---
|
