A.A shortage of liquid refrigerant
B.Excessive frost on the evaporator
C.Excessive condenser cooling water
D.Insufficient condenser cooling water flow
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A.eliminate hot air from the condenser
B.maintain steady pressure in a system
C.heat, or cool one fluid by means of another fluid
D.reduce the engine room temperature in tropical climates
A.Cross
B.Parallel
C.Counter
D.Circular
A.remain constant along the tubes length
B.be greatest in a single pass counter flow heat exchanger
C.remain constant throughout the heat exchanger
D.vary from section to section through out the heat exchanger
A.a low load on the unit
B.a clogged pump suction strainer
C.a blockage in the line between the pump and hydraulic motor
D.the hydraulic motor turning too fast
A.cause of salt contamination
B.location of salt water contamination
C.chemical makeup of feed-water
D.level of alkalinity in condensate
A.refrigerant overcharge
B.overfeeding by the expansion valve
C.a restricted suction strainer
D.due to short cycling of the compressor
A.capacity will increase
B.capacity will decrease
C.suction pressure will increase
D.suction pressure will decrease
A.hydraulic
B.electric
C.steam
D.diesel
A.increase the amount of cooling water to the condenser
B.decrease the amount of cooling water to the condenser
C.add more refrigerant to the system
D.remove some refrigerant from the system
A.Heat is given off from a high temperature region known as a heat sink
B.Heat transfer rate is affected most by the size of the heat sink involved
C.Heat transfer rate is affected most by the temperature difference between the heat source and the heat sink
D.Heat transfer by radiation will occur only by mass motion of a fluid substance
最新试题
The major source of chemical contaminants in hydraulic fluid is （）.
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
Which of the following statements is correct concerning heat transfer?（）
The general purpose of a heat exchanger is to （）.
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.