Question 22 1AE01 - First Assistant Engineer

The Correct Answer is B **Explanation for Option B (Correct Answer):** 1. **Function of Jacket Water Cooling Temperature Control:** The primary goal of the main engine jacket water cooling system temperature control is to ensure that the water entering the engine (the inlet header temperature) is maintained within a narrow, specified optimal range (e.g., typically around 80-85°C). Maintaining the correct *inlet* temperature is crucial for preventing thermal stress, ensuring proper combustion, and avoiding cold corrosion within the cylinders. 2. **Setup as a Mixer:** A 3-way valve used for temperature control in a jacket water system is almost universally configured as a **mixer**. It takes two distinct streams—one hot (water bypassing the cooler) and one cold (water returning from the cooler)—and combines them in the necessary proportions to achieve the desired resulting temperature. This mixed water is then directed to the engine inlet header. 3. **Control Location:** The temperature sensor (and thus the control function) is placed in the line **after** the mixing valve, and immediately **before** the water enters the engine (the inlet header). Therefore, the system controls the main engine jacket water **inlet header temperature**. **Explanation for Incorrect Options:** * **A) The main engine jacket water 3-way temperature control valve is setup as a diverter and is used to control the main engine jacket water outlet header temperature.** This is incorrect because the valve is configured as a mixer (combining hot and cold streams), not a diverter (splitting a single stream). Furthermore, the control system regulates the *inlet* temperature, not the *outlet* temperature (the outlet temperature is a result of the heat load). * **C) The main engine jacket water 3-way temperature control valve is setup as a mixer and is used to control the main engine jacket water outlet header temperature.** This is incorrect because while the valve is correctly identified as a mixer, the control system regulates the *inlet* header temperature, not the *outlet* header temperature. * **D) The main engine jacket water 3-way temperature control valve is setup as a diverter and is used to control the main engine jacket water inlet header temperature.** This is incorrect because the valve is configured as a mixer (combining streams), not a diverter (splitting streams).