Does anyone have experience with pre-heating fuel and direct injection
into the engine? I'm thinking a re-capture of heat from the engine
coolant via heat exchanger, (controlled and managed, of course, to the
optimum temperature/vapour pressure), to recoup some of the energy
lost. Fuel combustion would be almost instantaneous and no carburetor
or standard fuel injection would appear to work. Only direct injection,
which the rotary engine is very capable of.

This has come up before with my ideas on wing surface radiators. How
will the heated fuel in the wing tanks react when heated up to the
coolant temps (200-250 deg)? Fuel tanks would have to be well vented.
At what temperature would the fuel completely vaporize?(A bad thing).
Am I trying to get something for nothing, or does this idea have any
merit?

Thanks

Greg Fleming
London, Ontario, Canada

Great idea. Can I be there to film the resultant fireball?
Decker, Michael



Hi greg,

I know three different use of fuel pre-heating:

1/ In heavy fuel oil (FO2) fed large stationary diesels used for boats
and islands power plants.
The purpose of heavy fuel oil pre-heating (to about 100°C or 212 °f) is
to obtain the fuel fluidity required by the injection system.

2/ In natural gas fed heavy duty gas turbine used on power plants.
The purpose of natural gas pre-heating is to ensure instant ignition and
combustion stability in Dry Low NOx combustion chambers.

3/ In common rail injection systems used on modern diesel cars.
After high pressure compression (typically 150 to 250 MPa - 22.000 to
36.000 PSI) the light fuel oil is pre-heated obtain the fuel fluidity
required by the very thin injection system.
At such pressure and temperature, there is no more fontier between
liquid and gas.

On gazoline engine, where fuel is mixed to the air before compression,
pre-heating would be detrimental, as the cooler the inlet gases, the
easier the charge to compress, and the more mix to feed in.
(The mechanical energy gain on compression and the density of the gaz
charge are the explanation of intercooling in turbocharged engines)


Unless used as a havy fuel or a high pressure injected (turbo-compounded
?) diesel, I can't find any good reason to pre-heat fuel on a rotary engine.


Philippe

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