試題詳解

14.Rotary compressors are positive-displacement machines in which the gas being compressed is forced through the casing by one or more rotating displacement elements. Unlike a reciprocating compressor, a rotary compressor does not typically require internal suction or discharge valves. The flow from a rotary compressor is generally more uniform and has fewer pulsations than the flow from a reciprocating compressor. Therefore,
(A)the reciprocating compressor always provides the higher discharged pressure and efficiency.
(B)the rotary compressor is not capable of developing the suction head which always requires the positive suction head.
(C)the rotary compressor offers fewer pulsations than the reciprocating compressor.
(D)the rotary compressor requires positive suction head in order to have fewer pulsations than the flow from a reciprocating compressor.