Motor Plants & Auxiliary Boilers USCG Question #1138 (Set 22)

Which operating parameter may need to be decreased when running a large main propulsion diesel engine at low load conditions?

Official USCG Answer & Rule Citation

Correct Answer: Option A — Cooling water flow through aftercoolers

At low engine loads, exhaust gas energy drops, reducing turbocharger boost pressure and airflow. Restricting cooling water flow through the aftercooler prevents over-cooling of the intake air, avoiding misfiring, incomplete combustion, and excessive white smoke formation.

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