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Q1. Sketch and show all parts of a two-stroke engine stuffing box. Describe the procedure of overhauling two stroke engine stuffing box, without removing piston. Answer should include all safety precautions and necessary tools used for stuffing box overhaul. (16)

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Sketch and show all parts of a two-stroke engine stuffing box. Describe the procedure of overhauling two stroke engine stuffing box, without removing piston. All safety precautions and proper tools used for overhaul to be mentioned. (16)

Q2. NOx Tier-III requirements are getting mandatory as per MARPOL Annex VI. In this context, briefly explain the following:

a) Working principles and Components in a SCR system. (6)

b) Operational sequence of a NOX control SCR plant. (5)

c) Operational difficulties in SCR systems. (5)

Q3. Express your reactions and state the subsequent investigation you would make if a laboratory report on a used diesel engine oil sample indicated the presence of appreciable amounts of: (16)

A. Iron

B. Copper

C. Antimony and Tin

D. Silicon

E. n-pentane and toluene insoluble.

Q4. Describe the different types of crankshafts used in marine diesel engines. Highlight their constructional features, materials used, and typical applications. (8)

(b) Compare the advantages and disadvantages of semi-built and solid forged crankshafts with respect to strength, repairability, manufacturing process, and suitability for different engine sizes. (8)

Q5. a) Describe the actions and checks required to ensure that a crosshead main propulsion engine may be operated in a slow steaming condition. (8)

b) Explain the problems which may arise during a prolonged period of slow steaming. (4)

c) Explain what actions should be taken before and after the engine is returned to normal operation after a period of slow steaming. (4)

Q6. (a) Explain the need for a moment compensator in large two-stroke marine engines. With the help of a neat sketch, describe the construction and working principle of a moment compensator. (10)

(b) Discuss the consequences of failure or incorrect functioning of the moment compensator in a two-stroke engine. What checks and maintenance practices are recommended to ensure its reliability? (6)

Q7. a) Define Specific Cylinder Lubricating Oil Consumption (SCLOC) in a two-stroke marine diesel engine. Derive the formula for SCLOC and explain the procedure for calculating it during normal engine operation. (10)

b) Discuss the factors affecting SCLOC and explain the procedure adopted onboard to optimize cylinder oil consumption. Include methods used for monitoring and adjusting the cylinder lubrication system. (6)

Q8. With regards to modern diesel engine raising the Life Cycle Value (LCV) describe the importance of following. (16)

(a) Low Sac Volume of Fuel Injection Valve.

(b) Fuel Valve opening Pressure regulation.

(c) Contamination of combustion Chamber and impact on LCV.

(d) Contamination of lube oil and impact on LCV.

Q9. With reference to Modern Diesel Engine describe the features of High-pressure Miller cycle and discuss the following. (16)

(a) Reduction in Air Temperature due to Miller Cycle

(b) Recovery of Pressure in the Combustion chamber during the Miller cycle

(c) Effect of Miller Cycle on specific fuel consumption and NOx emission

(d) The impact on various parameters during low load operation using Miller cycle.