Diesel and gasoline engines have been the only way to move around since the 19th century (maybe with some small, electric exceptions for a short while). Though having low efficiency numbers (20 percent) when compared to their counterparts, gasoline engines still found their place on the market, mostly because in the first hundred years they had the advantage of being quicker, more responsive and now for not emitting soot and nitrous oxides.
Diesel engines, on the other hand, have been used mostly in heavy applications such as trucks, locomotives and various tools, because they’re the most efficient (around 40 percent), and mostly in European countries, where emission levels aren’t too tight. Diesels have had quite a growth in recent years, with the introduction of smart turbines as standard equipment and other various improvements that made them compete with gasoline engines, and even outrank them in many aspects (torque and consumption are just two of them).
To be used in the U.S., diesels still have to pass emission tests, which in some states are too stringent for current technologies to comply. Some even say the air that exits the cars’ tailpipes in those states is cleaner than the air that went in. Well, I doubt that’s true in real life conditions, but who am I to tell?
A mechanical engineer at Argonne National Laboratory, Steve Ciatti, is now studying a way to combine gasoline and diesel technologies into a kind of a hybrid engine. Gasoline needs a spark to detonate, while the diesel explosion is triggered by high air pressure. Despite the fact that they have lower CO2 emissions, because of that pressure and the high temperature inside the cylinder, nitrous oxides and soot are formed in diesels. Both of them are harmful for humans, causing cancers and respiratory problems.
Ciatti wants his future engine to create pressure, just like a diesel does, and then inject gasoline instead. Gasoline will not burn as quick as diesel when exposed to pressure, so several jets are needed, but the burn is cleaner. “That way, we can make sure that the most or all of the fuel is mixed with the air, significantly decreasing NOX and soot,” he says.
The engine he develops will only have 75% of the power a regular gasoline engine would have, but efficiency levels very close to diesels. “But if you don’t drive pedal to the metal, however,” Ciatti said, “this won’t affect the car’s performance. It’s excellent in the power range where most people actually drive.”
He also says this will greatly reduce the NOx and soot emissions, combining the cleanliness of a gasoline engine with the efficiency of a diesel. If you couple it in a hybrid drivetrain, you may seem to have the perfect recipe for an internal combustion engine – not always the perfect solution for our times, but better than nothing.
[via physorg]
Diesel burning gasoline is still dirty if one does not change the way it mixes fuel and air. With gasoline one can inject sooner and several times, because the fuel won´t react as easily allowing a better mixing and less emissions but a well mixed mixture could destroy an engine because burn rate might shyrocket and heat exchange will increase, reducing thermal eficiency. The real problem is simple. Piston engines don´t like burning very fast they are very fragil mechanical machines. To protect them one has to control their burn rate and diesel does that by mixing a very reactif fuel with air at the very last moment so reaction doesn´t start too early and combustion will go on in a difusion mode (very poor mixing) where the remaining injected fuel will burn only when enough air is around (with carbon fuels that´s very dirty). Detonation of a well mixed mixture (supersonic speeds) is the most eficient combustion, but no engine will resist such a violent event.
a at shadetree conversions we have been operating a diesel (tractor engine) powered pick up on gasoline ! we are heating the diesel in a steel tank mounted to the exhaust manifold to turn the fuel into gas vapor ! it will get about 15 to 20 miles on a pint of gasoline! we need help to design a throttle mechanism to be able to properly accelerate and control engine speed! any suggestions would be appreciated !!!!!!!