Gasoline-diesel 'cocktail' may lead to engine with 20 percent greater fuel efficiency

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Washington, August 4 (ANI): Scientists have developed a technique that mixes gasoline and diesel into a 'cocktail' within the combustion chamber of a vehicle, which means significantly lower pollutant emissions than conventional engines, with an average of 20 percent greater fuel efficiency as well.

These dramatic results came from a novel technique developed by the University of Wisconsin-Madison engine research group headed by Rolf Reitz.

Reitz describes the technique as "fast-response fuel blending," in which an engine's fuel injection is programmed to produce the optimal gasoline-diesel mix based on real-time operating conditions.

Under heavy-load operating conditions for a diesel truck, the fuel mix in Reitz' fueling strategy might be as high as 85 percent gasoline to 15 percent diesel.

Under lighter loads, the percentage of diesel would increase to a roughly 50-50 mix.

Normally, this type of blend wouldn't ignite in a diesel engine, because gasoline is less reactive than diesel and burns less easily.

But, in Reitz' strategy, just the right amount of diesel fuel injections provide the kick-start for ignition.

"You can think of the diesel spray as a collection of liquid spark plugs, essentially, that ignite the gasoline," said Reitz, the Wisconsin Distinguished Professor of Mechanical Engineering.

"The new strategy changes the fuel properties by blending the two fuels within the combustion chamber to precisely control the combustion process, based on when and how much diesel fuel is injected," he added.

Two remarkable things happen in the gasoline-diesel mix, according to Reitz.

First, the engine operates at much lower combustion temperatures because of the improved control - as much as 40 percent lower than conventional engines - which leads to far less energy loss from the engine through heat transfer.

Second, the customized fuel preparation controls the chemistry for optimal combustion.

That translates into less unburned fuel energy lost in the exhaust, and also fewer pollutant emissions being produced by the combustion process.

In addition, the system can use relatively inexpensive low-pressure fuel injection (commonly used in gasoline engines), instead of the high-pressure injection required by conventional diesel engines.

The best results achieved 53 percent thermal efficiency in the experimental test engine, which exceeds even the most efficient diesel engine currently in the world.

"For a small engine to even approach these massive engine efficiencies is remarkable," Reitz said.

"Even more striking, the blending strategy could also be applied to automotive gasoline engines, which usually average a much lower 25 percent thermal efficiency. Here, the potential for fuel economy improvement would even be larger than in diesel truck engines," he added. (ANI)

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