Q1. Discuss, with reference to the superheater outlet temperature of the main boiler operating at a constant load, the following statements:
a) An increase in excess air will tend to cause a decrease in superheater outlet temperature due to the cooling effect of more air being introduced.
b) A decrease in economizer inlet temperature will tend to cause a decrease in super heater outlet temperature due to the cooling effect of more water being introduced.
c) Badly fouled generating tube banks will cause an increase in the super heater outlet temperature.
d) Excessive amounts of total dissolved solids in the boiler water will cause variations in the super heater outlet temperature
Q2.a) Define fatigue and fracture and specify the conditions under which it occurs.
b) Describe the different fracture modes and the mechanism of crack propagation in different fracture modes.
Q3. With reference to propeller shaft alignment:
a) state the objectives of a satisfactory alignment
b) state the conditions that must be met to achieve satisfactory alignment
c) explain what is meant by fair curve alignment.
d)Define "sag and gap" in shaft alignment calculation.
Q5. GHG Ratings of ships have become new industry norms-Discuss various types of GHG Ratings applied to international shipping, with special focus on the role of second engineers in improving GHG ratings of ships.
Q6. With reference to feed regulation: A. Describe, with the aid of sketches, the operation of a boiler feed water regulator controlled by at least two other parameters besides water level in the drum; B. Give reasons for the inclusion of the other elements besides water level in controlling feed flow; C. Deduce the possible effects on the system when the drain valve in the constant leg in the level transmitter starts to leak.
Q6.a) Define the cause and effect of thermal stressing in cylinder heads, liners, and pistons.
Explain why thermal stressing is aggravated with an increase in the cylinder bore.
Explain how stress concentration and it's effects is relieved by maintenance and operational practices.
Q7. With reference to air conditioning units
a) With the aid of a sketch, explain the operation of a unit that includes means of dehumidifying, humidifying, and refrigerated cooling.
b) (i) Describe the conditions that could lead to legionella growth.
(ii) List the precautions necessary in the maintenance of air conditioning systems to reduce the risk of legionnaires disease being contacted.
Q8.a) Explain with a sketch the operation of an automatic expansion valve as fitted in the direct expansion refrigeration plants. How is this valve adjusted?
b) Explain how critical temperature restricts plant operation and how these limitations can be overcome?
c) Explain how this system maintains the provision rooms at different temperatures?
Q9. (a) Describe the properties of each of the following alloys used in marine engineering, giving a practical example for which, each is suited:
(i) cupro-nickel
(ii) white metal
(iii) titanium.
b) Discuss the merits of EACH of the following alloys for use in the casting of large propellers:
(i) nickel aluminium bronze (ii) stainless steel.
c) Describe the tests that may be carried out on steel to be used for ship's side plating.
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