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Q8. Explain vapor compression refrigeration cycle on T-S and PH diagram and explain the purpose of EACH of the following:

(a) Expansion valve

(b) Room thermostat

(c) High pressure cut out.

(d) Equalizing line. (16)

Q2. 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? (8)

b) Explain how critical temperature restricts plant operation and how these limitations can be overcome? (4)

c) Explain how this system maintains the provision rooms at different temperatures? (4)

Q2. a) Sketch and describe a high-pressure cut-out in a refrigeration system. (6)

b) The refrigeration compressor has stopped due to operation of the H.P. cut-out. (6)

Explain: (i) The possible causes.

ii) How these causes would be found and possible remedies.

c) What steps are taken if the compressor “Short-cycle” on low pressure cut-out? (4)

Previously Asked As

Q8. With reference to Air-conditioning system onboard your vessel:

(a) Sketch and describe high pressure cut-out in a refrigeration system.

(b) The refrigeration compressor has stopped due to operation of the h.p cut-out Explain.

(i) The possible cause.

(ii) How these causes would be found and possible remedies.

(c) What steps are taken if the compressor “short-cycle” on low pressure cut-out?