单项选择题
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
An increase in the heat load to a refrigeration system ...
单项选择题An increase in the heat load to a refrigeration system will cause （）.
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
Which of the following types of hydraulic pumps would b...
单项选择题Which of the following types of hydraulic pumps would be used in a steering system?（）
A.Lobe B.Screw C.Radial piston D.Volute
Which of the following statements is true concerning ce...
单项选择题Which of the following statements is true concerning centrifugal pumps?（）
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
