The piston cooling system may employ similar components, except that （） is used instead of a head tank.

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• Cavitation erosion in the cooling water system of a diesel engine usually occurs at the pump impeller, and on the waterside of the （）

  A . fuel nozzle holders B . exhaust value guides C . engine cylinder liners D . low temperature and a low viscosity

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• （） is sometimes used for piston cooling since leaks into the crankcase would not cause problems.

  A . Diesel oil B . Hydraulic oil C . Lube oil D . Mineral oil

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• Which of the following statements is correct for the design and installation of diesel engine cooling water systems?（）

  A . An alarm device with audible and visible signals is required for all cooling water systems B . Propulsion engines with bores over 200 mm are to be fitted with cooling water jackets C . Each totally enclosed cooling system shall be provided with a suitable head tank D . Drain cocks are to be provided at the lowest points of all cylinder water jacket

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• In a medium speed diesel engine, a trunk type piston may be cooled by（） Ⅰ.oil circulation though passages in the piston crown Ⅱ.heat transfer through piston rings and liner wall

  A . Ⅰ only B . Ⅱ only C . either Ⅰ or Ⅱ D . neither Ⅰ or Ⅱ

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• In a refrigeration system, if the cooling water to the condenser fails, the（）.

  A . box temperature solenoid valve will close B . expansion valve will close C . compressor will shutdown D . king valve will ope

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• In a closed cooling water system, which of the problems can cause the water pressure to fluctuate?（）

  A . An open vent in the cooling system B . A fouled sea chest C . A restricted water passage in the engine D . Air entrained in the cooling water

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• Large marine diesel engines of crosshead construction generally have two systems of lubrication: a total loss system feeding the （） and a recirculation system lubricating the running gear and cooling the piston.

  A . cylinder liners and piston rings B . main bearings C . crankpin bearings D . turboblower

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• The compressor in an air-cooled condensing refrigeration system is short cycling on the high pressure cutout switch（）

  A . system is overcharged with refrigerant B . system is low on refrigerant C . discharge valves are leaking excessively D . discharge valves are leaking slightly

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• The main distribution duct in an air conditioning system which contains the cooling coils and filters is called the（）

  A . manifold B . condenser C . chamber D . plenum

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• （）diesel engines generally have two systems of lubrication:（）a total loss system feeding and a circulating system lubricating the running gear and cooling the pistons.

  A . Large crosshead type；crossheads B . High speed；the cylinders C . Large crosshead type；the cylinders D . Four-stroke；pistons and cylinder

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• IBM System x and BladeCenter systems use cooling technology that allows managed airflow to each component.  What is the name of this technology？（）

  A . Calibrated Vectored Cooling B . Rear Door Heat eXchanger C . IBM Active Energy Manager D . Light Path Diagnostic

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• Around the combustion chamber, all the main components are bore cooled to give low strains and the smallest, circumferentially symmetric deformations for good sealing between piston rings and liner（）

  A . thermal B . mechanical C . plastic D . elastic

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• （） allows for expansion and water make up in the water cooling system.

  A . A top tank B . A head tank C . A head valve D . A drain tank

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• The jacket water temperature in a diesel engine closed freshwater cooling system is normally controlled by （）

  A . regulating the level of corrosion inhibitor in the primary cooling system B . the level of the freshwater expansion tank C . varying the engine load to meet temperature requirements D . the operation of the thermostatic valve

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• The expansion tank for a diesel engine closed cooling system is designed to maintain a constant head on the system and （）.

  A . reduce water temperature B . reduce water turbulence C . provide an air cushion D . allow for an increase in water volume as the engine warms u

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• In a diesel engine exhaust system, the cooling of the exhaust gases below their dew point, will result in （）

  A . increased engine back pressure B . sulfuric acid corrosion C . surface pitting of the turbocharger D . moisture impingement on the turbocharger compressor blade

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• In the closed cooling system, the water （）.

  A . is made to circulate out of the system B . is made to circulate within the system C . is made circulate within the system D . is made circulate out of the system

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• Which of the following problems can cause fluctuating pressures in the closed cooling system of a main propulsion diesel engine?（）

  A . Defective temperature controls in the system B . Cavitation in the cooling water pump C . Opened vent in the cooling system D . Restricted water passages in the engine

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• If the coolant temperature of a closed cooling water system for a diesel engine gradually increases, the trouble usually is （）

  A . a broken shaft on the freshwater pump B . an excessive accumulation of scale exchanger C . an incorrect thermostatic element operating range D . lube oil in the cooling water

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• There is a （） system lubricating the running gear and cooling the piston and sometimes lubricating the cylinders.

  A . recirculating B . total loss C . cooling D . refrigeratio

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• In motor-ships, （）, after passing through main and motion bearings and oil cooled pistons, etcis either retained in the bedplate.

  A . the fuel oil B . the lubricating oil C . the refrigerating oil D . the hydraulic oil

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• Which of the following statements is correct concerning diesel engine cooling water systems?（）

  A . Each engine must have its own engine driven cooling water pump capable of providing cooling for all ranges of operation B . propulsion engines with bores exceeding 200 mm are to be fitted with a means to display the cooling water temperature of each cylinder C . At least two independent sea suctions are to be provided for supplying water to the engine jackets or to the heat exchangers D . Suitable strain are to be fitted between the circulating pumps and heat exchangers when sea water is used for direct cooling

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• The piston crown employs the usual jet-shaker principle with an arrangement of cooling bores in the crown so that the surface temperatures of the crown are moderate with a very even distribution.

  A.water cooling B.oil cooling C.air cooling D.combined cooling

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• On engines having oil cooled pistons the lubricating oil pre-heater must be put into operation and the rate of heating so ______ that the temperature of the piston cooling oil returns are 32 to 35℃ over a period of at least two hours.

  A.slow B.quick C.arranged D.high

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