What is the purpose of an exhaust gas recirculation (EGR) system in a car's engine, and how does it reduce nitrogen oxide (NOx) emissions by recirculating exhaust gases back into the combustion chamber?

An exhaust gas recirculation (EGR) system is designed to reduce nitrogen oxide (NOx) emissions by recirculating a portion of the engine’s exhaust gases back into the combustion chamber. By reintroducing inert exhaust gases into the cylinder, the EGR system lowers the peak combustion temperature, which reduces the formation of nitrogen oxides. This helps vehicles comply with emissions regulations while maintaining engine efficiency and performance.