A.change in impeller diameter
B.square of the impeller diameter
C.cube of the impeller diameter
D.impeller efficiency for large changes in the size of the impeller
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A.the suction pressure to decrease
B.the suction temperature to increase
C.increased ice formation on the evaporator coil
D.excessive short cycling of the compressor
A.Lobe
B.Screw
C.Radial piston
D.Volute
A.They are particularly suited for pumping high viscosity fluids
B.They are started with the discharge valve opened
C.The flow of liquid is developed by imparting energy due to the rotation of an impeller
D.They are always mounted in a horizontal position
A.refrigerant pressure in the evaporator
B.cooling water temperature to the condenser
C.heat load in the refrigerator compartment
D.solenoid valve in the liquid line
A.compressor
B.condenser
C.expansion valve
D.evaporator
A.bimetallic type
B.diaphragm type
C.bourdon tube type
D.resistance-temperature type
A.evaporator coils
B.liquid strainer
C.compressor
D.condenser
A.suction side of a bilge pump
B.exhaust manifold of an auxiliary diesel
C.discharge line from an air compressor
D.chemical feed tank of an evaporator
A.They should always be started with the discharge valve closed
B.They should always be started with the discharge valve opened
C.A priming pump is always required to flood the impeller suction
D.They should always be started with the sealing line valves closed
A.compressor damage from improper lubrication
B.refrigerant absorption by the lubricant
C.increased viscosity in the lubricant
D.carbon deposit on the compressor suction valves
最新试题
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
Thermostatic expansion valves can be adjusted for （）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
A grease gun is generally used to lubricate a （）.
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
The major source of chemical contaminants in hydraulic fluid is （）.