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单项选择题

钢质活塞顶面裂纹时，可采用_______修复

A.焊接
B.金属扣合
C.粘接
D.局部更换
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相关考题

单项选择题
先后由建筑大师格罗皮乌斯与密斯·凡·德·罗担任校长的位于德国德绍的工艺和建筑学院被简称为：( )
A.包豪斯
B.德绍设计学院
C.魏玛实用美术学院
D.魏玛公立建筑学院
单项选择题
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
A.Fouling
B.,
C.
Plate
D.the
E.the
F.the
G.the
单项选择题
下面哪一项不会使总需求曲线移动?________。
A.对未来的预期
B.货币工资率
C.财政和货币政策
D.外国收入
E.外汇汇率
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