Question

NOx is reduced in a CI engine by the use of EGR.

(a) increased

(b) reduced

(c) unpredictable

(d) none of the mentioned

I had been asked this question in exam.

This key question is from C.I. Engines in section Engine Emissions and their Control of IC Engine

Answer 1

The correct answer is:

(b) reduced

NOx (Nitrogen Oxides) emissions are reduced in a CI (Compression Ignition) engine by the use of Exhaust Gas Recirculation (EGR). EGR works by recirculating a portion of the exhaust gases back into the intake air, which lowers the combustion temperature, thus reducing the formation of NOx, which is primarily formed at high temperatures.