We know a turbo charger will generate some boost pressure at that HP
level.
We know it takes HP to generate boost pressure. Obviously there is
some
kinetic or pressure energy in there or the turbo charger would not
spin.
We also can hear the exhaust and noise takes HP to generate.
Here are some of the things we don't know yet:
We don't know how much is kinetic energy, pressure energy or is just
plain
heated gas at atmospheric pressure.
Paul Lamar
The useful energy in the exhaust is no where near the 50HP worth of
BTU's
The exhaust gas velocity
is a total pressure, and it got that by the exhaust stroke using work
to
push the gases out. Even perfect
recovery expansion will not harness as much power as you are
anticipating.
If you look at
PV diagram for the Otto cycle at part power, you will see that that
big drop
at the bottom of
the expansion stroke has almost disapeared. The only amount of
theoretical
work that is
available is the tiny triangle area that you would get extrapolating
that
expansion to ambient
pressure. I fear that Monty has a much better grasp of the
thermodynamics
and gas dynamics
of these cases than you - sorry Paul, de debbil made me do it. - Vance
I am sure he does but I am not willing to give up just yet.
So in your opinion it is impossible to recover 2/3rd of the heat in a
gallon of gas? Only one third can be recovered? What do you suggest?
Switching to 60% efficient combined cycle gas turbines in our cars.
Paul Lamar
Here is a car turbo compound configuration that Monty and Vance will love.
A 2.5 rotor engine. 300 HP total. Runs only on the front 50 HP rotor
When cruising down the highway at a steady 80 MPH. It feeds its power
through the main
engines e-shaft using a long quill shaft. It runs at wide open throttle
and
6000 RPM with a 2:1 gear reduction into the transmission. When passing or
hill climbing the main engine kicks in.
My guess it it would add 50 pounds to the engine and be cheaper than
a hybrid.
Paul Lamar
I seriously doubt that this would be cheaper than a hybrid. This is the
4-6-8 theory
taken to the next step - ie dual engines swithed in and out, and one watch
like
CV transmission with all sorts of mechanical controls. I can only imagine
the
thrashing and clanging of all those controls while darting and dodging thru
the LA traffic.
I reall think that the electrical, turbocompound
hybrid has a lot more potential - and it rolls easily off the tongue for
brochure talk.
I once proposed an extended expansion cycle (modestly called the Jaqua
cycle)
for an article on engine efficiency for Contact Magazine. This might be
considered to be an analog of turbocompunding, with the work being
extracted before the gases left the combustion chamber, unimpeded by valve
or
ports. The version shown utilized an opposed piston engine with cranks
rotating at different speeds. This could easily accomplished with a cam
(ugh)
engine, or the frequently proposed (but with lack success) rotory vane
engine
. However, I do not think that it can be accomplished with a Wankel. Vance
4-6-8 has been perfected. The very popular new Dodge or Chrysler 300 hemi V8 uses it
to great advantage. The draw back of 4-6-8 compared to this design is you still
have the friction and inertia of the dead cylinders. In this design the main
engine is dormant or idling.
Mazda has the technology to make this work at low cost. It would be a piece of cake
for Mazda and probably cost far less than a hybrid. Beside that there are no expensive
nickel metal hydride batteries to replace every several years.
Electric turbo compounding is not worth it. By the time you convert
mechanical energy from the blow down turbine to electrical energy, charge batteries
and than convert it back to mechanical energy you are down to 60 or 70% of 20% or
12 or 14%. Not worth the extra weight and expenses of all the electrical
stuff and the batteries required. Just like a current hybrid is not worth it.
Paul Lamar
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