问题
单项选择题
在一间壁换热器中，两流体均在湍流下进行换热。冷热流体的对流传热系数分别为150kW/(m2·℃)和300kW/(m2·℃)。若仅使某一侧流体的流速加倍以强化传热，则总传热系数增加的最大百分数大约为( )。(可按平壁处理，忽略管壁热阻、污垢热阻和热损失)
A．(16%
B．(20%
C．(40%
D．(50%
答案
参考答案：C
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在一间壁换热器中，两流体均在湍流下进行换热。冷热流体的对流传热系数分别为150kW/(m2·℃)和300kW/(m2·℃)。若仅使某一侧流体的流速加倍以强化传热，则总传热系数增加的最大百分数大约为( )。(可按平壁处理，忽略管壁热阻、污垢热阻和热损失)
A．(16%
B．(20%
C．(40%
D．(50%
参考答案：C
完形填空（10分） Many Americans like to have their holidays(假期) in 1 countries. One day an American 2 comes to China. This is her first time to China and she wants to 3 some friends here. She meets a Chinese. This Chinese wants to talk 4 with the American. When he sees her, he comes up and says “ 5 ” , then he begins(开始) his first talk with someone 6 an English-speaking country（国家）. “How old are you?” the Chinese 7 . “I’m 8 . It’s a secret. Please don’t ask a lady(女士) about her 9 .” answers the woman. The Chinese is surprised (感到惊奇) . He doesn’t know 10 . Can you help him?
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