Public Release: 

Cleaner cars

New Scientist

Run a car engine for half an hour, and 80 per cent of its hydrocarbon emissions will be spewed out in the first two minutes, while it's still cold. But American researchers have found a way to make an engine behave as if it's warmed up all along, reducing pollution from the moment you turn the ignition key.

Their secret? To keep a proportion of the car's most volatile fuel to one side and use it for the engine's starting phase.

Car engines can only burn petrol once it has been vaporised. But much of the fuel drawn into a cold engine remains as a liquid and is emitted from the exhaust without being burnt. This unburnt fuel reacts with nitrogen oxides to create ozone, one of the major components of smog.

To counter this, the researchers have developed a distillation device that uses heat from the car's engine to separate out the 5 per cent of the fuel made of the smallest, most easily vaporised hydrocarbon molecules. This is stored in a separate reservoir to be used when the engine is started. Since most of this fuel is vaporised even in a cold engine, it slashes the amount of unburnt hydrocarbons emitted by more than 50 per cent in the start-up phase. The new distillation gadget weighs just 2.5 kilograms.

The device was designed and patented by engineers at the University of Texas in Austin and the Ford Motor Company. "The engine will behave as if it's fully warmed up, even when it isn't," says Rudy Stanglmaier, one of the inventors at UT's Southwest Research Institute. Ford will test it this year in a Lincoln Navigator.

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Author: Nicola Jones

More at: Journal of Environmental Radioactivity (vol 53, p 231)

New Scientist issue: 3rd February 2001

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