Exam Question
(a) What is the significance of an air cooler and why is the scavenge air temperature preferred to be maintained at 40°C? (8)
(b) What are the probable indications of a leaky air cooler as fitted to a two stroke main engine? (8)
Class 4 (4th Engineer)
MEKM
📅 Oct 2025
Reference Answer
### Part (a): Significance of the Air Cooler and Scavenge Air Temperature Control
#### 1. Significance of the Air Cooler (Charge Air Cooler)
The primary function of an air cooler in a two-stroke marine diesel engine is to increase the charge air density, which directly enhances the engine's power output and thermal efficiency.
* **Working Principle**: The turbocharger compresses intake air to a higher pressure (e.g., 3-4 bar). According to the gas laws, this compression significantly increases the air's temperature (to as high as 180-220°C).
#### 1. Significance of the Air Cooler (Charge Air Cooler)
The primary function of an air cooler in a two-stroke marine diesel engine is to increase the charge air density, which directly enhances the engine's power output and thermal efficiency.
* **Working Principle**: The turbocharger compresses intake air to a higher pressure (e.g., 3-4 bar). According to the gas laws, this compression significantly increases the air's temperature (to as high as 180-220°C).
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