What is exhaust gas recirculation?
Exhaust Gas Recirculation or EGR, is a process developed to reduce a type of harmful air pollution. It is primarily used as an emissions control device on fuel driven engines. EGR systems control the amount of NOx (oxides of nitrogen) expelled from the exhaust of an engine by controlling the temperature of the combustion chamber. Specifically, under heavy engine loads, the internal temperature becomes ideal to create oxides of nitrogen. Reducing NOx is done by reintroducing an inert gas into the combustion process to keep the temperatures down – mainly the Carbon Dioxide which the engine already expells. The system is mechanically simple as it is nothing more than a valve which taps the exhaust gasses and plumbs it into the engines intake manifold. The timing of the valve can sometimes be a bit more complex, from a simple system operated by a vacuum line, or entirely computer controlled. In either case, the valve is designed to proportionately meter exhaust gas into the cylinder in hig
