Re: Car mounted electrolyzers for improved MPG


"Al" <bigal@xxxxxxxxxx> wrote in message
news:42ae412b.144296365@xxxxxxxxxxxxxxxxxx
> On Mon, 13 Jun 2005 09:05:53 -0500, "charliew2" <charliew@xxxxxxx>
> wrote:
>
> >"Al" <bigal@xxxxxxxxxx> wrote in message
> >news:42acdc92.52993310@xxxxxxxxxxxxxxxxxx
>
> >> Preheating the air is exactly the opposite of what you want to do.
> >>
> >> Heating air makes it expand. Therefore you can't fit as much into
> >> each cylinder. Frictional losses on a mass basis go up as well.
> >
> >You can if you pressurize it, which is what a turbocharger does.
>
> Yes, the point of a turbocharger is to pack more air into each
> cylinder.
>
> The problem is, when you compress air it gets hot. If you cool it
> after compression, the density increases further. Therefore you can
> get even more air into the cylinder. That's why some turbocharged
> engines use intercoolers.
>
> Heating the air, then compressing it is just... dumb.
>
> >> Note that many turbocharged engines use something called an
> >> "intercooler", which is used to *cool* the air coming out of the
> >> turbocharger before it goes into the cylinders. (Compressing air in a
> >> turbocharger makes it hot.)
> >
> >I'm familiar with intercoolers. They are used to minimize the size of
the
> >turbocharger by giving the second stage of the turbocharger a gas which
is
> >easier to compress.
>
> Wrong. See my above comment.
>
> >Thanks for the feedback. My question may have been premature - while it
is
> >technically correct to want air preheat in order to increase thermal
> >efficiency, offsetting factors make this approach impractical. In
addition,
> >as long as you have a large heat rejection to the atmosphere at the
> >radiator, air preheat doesn't make sense - such a technique wouldn't be
used
> >on any engine with a radiator.
>
> Preheating the air in an industrial furnace *does* make sense if
> you're drawing that heat out of the exhaust stream.
>
> But preheating the air in any sort of engine that requires compression
> of the intake air is not done simply because it makes no thermodynamic
> sense.


I see that you are from an educational institution, so I will ask a question
along this line.

Lets assume that you only had a single stage turbocharger (i.e., no
intercooler). Would it make thermodynamic sense to use energy from the
exhaust stream to compress intake air, and then send this hot intake air
into the intake manifold? In a sense, intake air is being preheated by the
heat of compression from the turbocharger, as pointed out in some of your
commentary above. So, what's your answer?


.

Relevant Pages

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