What is the function of an EGR valve?

[McSabrina]

EGR valve is used to reduce the emission of nitrogen oxides (NOX) in exhaust gases. Nitrogen and oxygen only undergo chemical reactions under high temperature and high-pressure conditions, which are met in the engine combustion chamber, especially during forced acceleration. EGR stands for Exhaust Gas Recirculation system. When the engine is operating under load, the EGR valve opens, allowing a small amount of exhaust gas to enter the intake manifold and mix with the combustible mixture before entering the combustion chamber. During idle, the EGR valve closes, preventing any exhaust gas from recirculating into the engine. Automobile exhaust is a non-combustible gas (containing no fuel or oxidizer) and does not participate in combustion within the combustion chamber. It reduces the combustion temperature and pressure by absorbing part of the heat generated during combustion, thereby decreasing the production of nitrogen oxides.