>
     > This is from the 1952 SAE Transactions.
     > Development of the R3350 Turbo Compound
     > Engine.
     >
     > The last chart illustrates yet another advantage
     > of turbo compounding. It improves the power
     > to weight ratio of an engine.
     >
     > -------------------------------------------------
     >
     > This power recovery heat balance chart knocked me out of my chair.
     > I had NO IDEA.... NONE WHAT SO EVER, prior to now, so much energy
     > was wasted by the exhaust valves in a piston engine turbo compounds.
     >
     > Need I mention yet again THE WANKEL ROTARY HAS NO BLEEDING
     > EXHAUST VALVES!!!.
     >
     > More evidence we will eventually get more than a 20%
     > efficiency improvement with a turbo compound rotary.
     >
     > I am not making this stuff up folks.
     >
     > --
     > Paul Lamar ...No rotor no motor.

    Paul,
    What is SENSIBLE energy and what is NON-USABLE sensible energy?
    George (down under)

    Sensible energy is heat or motion that can be sensed.
    Non sensible energy is chemical or gas products I think.

    Paul Lamar ...No rotor no motor.
    --------------------------------------------------------------------------------

    Here is a simple definition.

    SENSIBLE HEAT
     If a substance is heated (heat added) and the temperature rises as
    the heat is added,  the increase in heat is called sensible heat.
    Likewise, heat may be removed from a substance (heat subtracted).
    If the temperature falls, the heat removed is, again, sensible heat.

    Heat which caused a change in temperature in a substance is called
    sensible heat.

    LATENT HEAT
    A physical phenomenon of all pure substances is their ability to
    change state.  Solids become liquid, liquids become gas or the
    reverse.  These state changes occur at given temperature and
    pressure for the substance and the temperature does not change until
    the state change is complete.  Heat energy must be added or removed
    to produce the state change.
    Heat which bring about a CHANGE OF STATE, WITH NO CHANGE IN
    TEMPERATURE, IS CALLED LATENT (hidden) HEAT.

    Joel

Paul:

What is the minimum output Wankel in which this technology is worth
pursuing?  There are weight/complexity/cost issues here.  Obviously, unit
costs drop as production rate rises - unless the technologies required for
key components are a bottleneck because of limited available tooling,
machinery, required technicians, etc., etc.  Is there anything exotic or
subject to rapid cost changes that could be a stumbling block?  My concern
is that all technologies tend to go through three stages:  1)  can it be
done at all?; 2)It can be done as a technology demonstrator, but requires
high initial investment and/or high cost support staff; 3)Dude, anyone who
almost passed 8th grade can do it!  I'm assuming we are about stage 2 with
this technology.  How practical is it to get to stage 3 where the concept
can take off?

best,
George Wright

Stage 2 is about right George.

If you scale everything down and insulate hot parts  I don't think there
is any practical minimum size. The reason you may need to insulate
hot parts is the surface to volume ratio becomes less favorable
as you make a pipe smaller. In our case you certainly don't need
to insulate anything as the exhaust is already 1700 to 1800 F.
I think half 13B size would still work well.

On the contrary one could insert a heat exchanger between the exhaust port
(combuster) and the turbine and make steam. Then inject that steam back into the
gas turbine as is done in some combined cycle engines. That will cool the
exhaust gas going into the turbine and the injected steam will help spin
the turbine and cool it at the same time. Water can be recovered from the
exhaust. Probably not practical for an airplane but could possibly be
used in a car somewhat similar to what BMW is doing.  See the 3D attachment.

BTW the exhaust valve kills you in two ways. It extract heat from
exhaust gas which is lost to the cooling system and it obstructs
the rapid flow of exhaust gas out the exhaust ports (kinetic energy).
Both counter productive to a turbo compound engine.

Lets look at the heat balance with out the exhaust valves.
Total heat available to the turbine now over doubles to
34.7% from 14.9%. The losses to gears and bearings also doubles
to say 3%. Windage and cooling loss goes to 3.2% from 1.6% and
aero and thermal losses got to 12% from 6%. Total loss percentage
is then 18.2%. 34.7% kinetic energy available for recovery
minus 18.2% losses is 16.5%! Up from only 6% with exhaust valves.

Total fuel energy burned in a 200 HP rotary is about 760 HP worth.
With exhaust valves you would have only about 6% or
45.6 HP available for the turbine.

Without exhaust valves you would have about 16.5% or 125 HP!!!!
Almost three times the HP available to drive the turbine!!! No wonder
you can boost a 13B rotary to 800 HP!! There is lots of kinetic HP to
be had in the rotary engine exhaust. Much, MUCH more than I had at
first thought. We always knew there was a lot of waste heat in
the rotary exhaust. Up to 50% of the total heat. What we did not
know up until now was what we could expect in terms of kinetic energy.

Paul Lamar ...No rotor no motor.

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