DieselShip's Online Content Library

Q1. Explain the functional and constructional difference between the Torsional and Axial vibration dampers with the help of neat sketches, Explain the function of the side and Top bracing of the main engine.

Q2. a) Explain the term fuel ignition quality and indicate how a fuel’s chemical structure  Influences its value
b) State, with reasons, the possible consequences of operating an engine on a fuel with a lower ignition quality than that for which it is timed.
c) (i) Explain how an engine might be adjusted to burn fuel of different ignition quality.
(ii) State what checks can be carried out in order to determine that the engine is operating correctly.

Q3. What is slow steaming & how it’s achieved without engine modification? Enumerate various operational issues with slow steaming. How such operational issues can be dealt with?

Q6. Selective catalytic Reactors (SCR) are being extensively used in marine diesel engines for the compliance of Tier-III NOx emission requirements. Explain various types of SCRs in use with particular focus on the following:-

a) High-Pressure SCRs (HPSCR) vs Low-Pressure SCRs (LPSCR)

b) SCRs with static mixers.

c) SCRs installed upstream the turbocharger(s) Vs downstream turbochargers.

Q2. With reference to behaviour of fabricated bed plates and frames in services:

A. Identify various forces imposed simultaneously upon them;

B. Explain how engine structure withstands these forces;

C. State how these forces are transferred to ship’s structure

Q6. Electronically controlled marine diesel engines are said to provide advantages over the traditional engines in the following areas

a) Improved fuel economy

b) Emission control

c)Engine response during manoeuvring, especially crash movements.

Explain how these are achieved.

Q7. A. State, with reasons, THREE properties required of crankcase oil which is to be used for a trunk piston main engine.

B. Explain how a representative sample of crankcase oil would be obtained from a trunk piston engine. C. Briefly describe the action to be taken if the crankcase oil charge cannot immediately be replaced and analysis shows – (i) Water is present; (ii) Alkalinity has fallen; (iii) Viscosity has changed appreciably; (iv) Carbon content has increased.

Q8. a) To improve the power-to-weight ratio of an engine, it is necessary to increase the mep. Discuss the importance of turbocharger compression ratio in this regard. Why has it become necessary to introduce two-stage turbocharging?

b) With reference to turbochargers with variable turbine area, explain

i)Which area is varied

ii)Why is it varied

iii)How is it varied.

Q9. With respect to the refrigeration system on board vessels, answer the following
a) Why are some TEVs fitted with an external equalising connection?

b) What is the purpose of a back pressure valve. what will the effect if it leaks?

c)How does an electronic TEV function.