【单选题】若换热器的换热管为金属材料,当管壁很薄时,间壁两侧流体的对流传热膜系数相差悬殊,则要求提高传热系数以加快传热速率时,必须设法提高 ( ) 的膜系数才能见效。
【判断题】当间壁两侧对流传热膜系数相差很大时,传热系数K接近于较大的膜系数。
【单选题】When invited out for 'supper' a few weeks later, the writer______.
A.
expected to be served a proper dinner
B.
arrived on the wrong evening
C.
interpreted the invitation correctly this time
D.
realized there was no dinning-room in the cottage
【单选题】When invited for a dinner, start eating when:
B.
any one starts eating.
D.
guest of honor starts.
【简答题】当间壁两侧冷,热流体的对流传热膜系数α相差很大时,传热系数接近于()一侧的α值。
【判断题】当间壁两侧对流传热服系数相差很大时,传热系数k接近于较大的膜系数。
【单选题】当间壁两侧对流传热膜系数相差很大时,传热系数Κ接近于( )。