题目内容

活塞顶部烧蚀可采用_______进行测量

A. 塞尺
B. 深度游标卡尺
C. 测微尺
D. 样板和塞尺

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滞胀是实际GDP________和价格水平________的结合。

A. 上升;上升
B. 上升;下降
C. 下降;上升
D. 下降;下降
E. 不变;上升

If a heavy sea strikes the rudder, the shock is transmitted through ___ to the rams, this

A. the control rod
B. the hunting gear
C. the floating ring
D. the tiller arm

Oil Pollution Regulations require any transfer or discharge of oil or oily mixtures to be

A. bridge log
B. Master's log
C. engine room log
D. oil record

第二组
The only attention that heat exchanger should require is to ensure that the heat transfer surfaces remain substantially clean and the flow passages generally clear of obstruction. Indication that undue fouling is occurring is given by a progressive increase in the temperature difference between the two fluids, over a period of time, usually accompanied by a noticeable rise in pressure loss at a given flow.
Fouling on the sea-water side is the most usual cause of deterioration in performance. The method of cleaning the sea water-side surfaces depends on the type of heat exchanger. With shell-and-tube heat exchangers, the removal of the header covers or, m the case of the smaller heat exchangers, the headers themselves, will provide access to the tubes. Obstructions, dirt, scale etc., can then be removed, using the tools provided by the heat exchanger manufacturer. Flushing through with fresh water is recommended before a heat exchanger is returned to service. In some applications, such as piston oil cooling, progressive fouling may take place on the outside of the tubes. Most manufactures recommend a chemical flushing pr6cess to remove this in situ~ without dismantling the heat exchanger.
Plate heat exchangers may be cleaned by unclamping the stack of plates and mechanically cleaning the surface of each plate as recommended by the manufacturers. The plate seals may require replacement from time to time and here the manufacturers&39; instructions should be closely followed
By which of the following indication, can we conclude that the lube oil-sea water heat exchanger is unduly fouled?

A. the heat exchanger lube oil inlet temperature lowering
B. the heat exchanger sea-water outlet pressure rise
C. the heat exchanger temperature difference between lube oil and sea water increasing
D. the heat exchanger pressure difference between sea water inlet and outlet decreasing

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