Exhaust gas recirculation

摘要

The automotive industry's historic heavy dependance on fossil fuels has meant the release of harmful emissions into the atmosphere hasn't been eradicated and remains an unfortunate by-product of the combustion engine. The toxic gases released, not only pollute the atmosphere and contribute to the increasing threats posed by global warming, but also have an adverse effect on the health of any individual who happens to breathe them in. This continues to be one of the most pressing challenges for automotive engineers to overcome - as each time a target is met, the goalposts are shifted again. Nitrogen oxides such as nitric oxide and nitrogen dioxide (or NOx) are both major contributors to air pollution. Oxygen and nitrogen are harmless and inert when in cool temperatures, but in the fiercely hot conditions of the combustion engine, both react with each other to produce the more harmful gas.