4.下列何者為泵的機械效率？ (A)實際揚程與理論揚程之比 (B)理論流量與實際流量之比 (C)有效功率與軸功率之比 (D)理論計算的功率與輸入功率之比

9.Blowers are used with many diesel engines to supply the air necessary for combustion to the engine’s cylinders. When the pressure of this air is increased above atmospheric pressure, referred to as supercharging, the power output of engine is increased. In addition, in a two-stroke engine the air supplied by the blower helps to purge the engine’s cylinders of exhaust gas. This is referred to as scavenging. Based on these descriptions, please specify the correct statement. (A)The scavenging and supercharging processes share identical purpose of increasing the static pressure in the intake pipes. (B)The use of blow for scavenging and supercharging is due to its characteristics of high-pressure and low volumetric flow rate. (C)The blower for marine application is always the centrifugal type as it offers the high speed characteristic. (D)The scavenging in a two-stroke engine assists to purge the engine’s exhaust gas which has beneficial effect for combustion.

4.下列何者為泵的機械效率？
(A)實際揚程與理論揚程之比
(B)理論流量與實際流量之比
(C)有效功率與軸功率之比
(D)理論計算的功率與輸入功率之比

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