Exam Question
Explain with a simple line sketch, a main engine jacket cooling automatic control system capable of maintaining the jacket water temperature within close limits during wide changes in engine load. (16)
Class 4 (4th Engineer)
MET
📅 Mar 2026
Reference Answer
### **Objective of the Automatic Control System**
The primary objective of a main engine jacket cooling water automatic control system is to maintain the jacket water outlet temperature at an optimal, stable setpoint (typically 80-90°C) under all operational conditions, from maneuvering and low load to full sea passage. Maintaining this temperature within close limits is critical for:
* **Preventing Thermal Shock:** Rapid temperature changes can cause micro-cracking in cylinder liners and heads due to differential thermal expansion and contraction.
* **Avoiding Cold Corrosion:** Keeping the liner surface temperature above the dew point of sulfuric acid (H₂SO₄) prevents acid condensation. Sulfuric acid forms from the combination of sulfur in the fuel and water from combustion.
The primary objective of a main engine jacket cooling water automatic control system is to maintain the jacket water outlet temperature at an optimal, stable setpoint (typically 80-90°C) under all operational conditions, from maneuvering and low load to full sea passage. Maintaining this temperature within close limits is critical for:
* **Preventing Thermal Shock:** Rapid temperature changes can cause micro-cracking in cylinder liners and heads due to differential thermal expansion and contraction.
* **Avoiding Cold Corrosion:** Keeping the liner surface temperature above the dew point of sulfuric acid (H₂SO₄) prevents acid condensation. Sulfuric acid forms from the combination of sulfur in the fuel and water from combustion.
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