Question Bank • QB_FP_ADV_081 MSQ • 2 Marks

Section 3: Farm Power

Farm Power

Subtopic: I.C. engine systems – fuel, cooling, lubrication, ignition, electrical, intake and exhaust

Question Statement:

To comply with advanced off-road emission standards (Bharat Stage Trem IV / Trem V and US EPA Tier 4 Final) for agricultural tractors, which of the following after-treatment and engine control technologies are deployed?

Options:

  • (A) Cooled Exhaust Gas Recirculation (EGR) to suppress peak combustion temperatures and lower $\text{NO}_x$ emissions
  • (B) Diesel Particulate Filter (DPF) to trap and periodically burn (regenerate) carbonaceous soot particulate matter
  • (C) Selective Catalytic Reduction (SCR) utilizing aqueous urea (Diesel Exhaust Fluid / AdBlue) injection to reduce $\text{NO}_x$ into harmless $\text{N}_2$ and $\text{H}_2\text{O}$
  • (D) Carburetor air-bleed solenoids to regulate stoichiometric gasoline mixture

Answer Key:

A, B, C

Step-by-Step Solution & Explanation

- **A is correct:** Cooled EGR replaces excess oxygen with inert exhaust gas, lowering peak flame temperatures and curbing thermal $\text{NO}_x$. - **B is correct:** Wall-flow DPF filters trap
gt; 90\%$ of particulate soot. - **C is correct:** SCR catalytic converter uses DEF ($32.5\%$ urea solution) which hydrolyzes to ammonia ($NH_3$) and reacts with $\text{NO}_x$ to form nitrogen and water. - **D is incorrect:** Farm tractors are compression-ignition diesel engines and do not use carburetors.
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