Subtopic: Selection, operation, maintenance and repair of I.C. engines
Question Statement:
Which of the following technologies are deployed in modern agricultural tractors to comply with Bharat Stage TREM IV / Stage V emission standards?
Options:
(A) Cooled Exhaust Gas Recirculation (EGR) to suppress peak combustion temperatures and minimize $NO_x$ formation.
(B) Selective Catalytic Reduction (SCR) dosing aqueous urea (DEF / AdBlue) to reduce $NO_x$ to harmless nitrogen and water vapor.
(C) Diesel Particulate Filter (DPF) to capture and periodically burn off fine soot particles.
(D) Mechanical carburetors with float chambers for fine air-fuel metering.
Answer Key:
A, B, C
Step-by-Step Solution & Explanation
• Cooled EGR reduces $NO_x$ by thermal dilution (A is correct).
• SCR treats downstream exhaust with urea to convert $NO_x$ into $N_2$ and $H_2O$ (B is correct).
• DPF traps solid carbonaceous particulates (C is correct).
• Diesel engines use high-pressure fuel injection (CRDI), not carburetors (D is false).