题目内容

A copper tube with the outer diameter of 24 mm, wall thickness of 1.5 mm and conductivity of 101 W/(m.K) is used inside a condenser. Cold water flows inside the tube and vaper condenses outside the tube. The convective heat transfer cofficients outside and inside the tube are 9500 W/(m2.K) and 6050 W/(m2.K), which of the following is overall the heat transfer cofficient based on the outer surface?

A. 8050 W/(m2.K)
B. 7300 W/(m2.K)
C. 3225 W/(m2.K)
D. 125 W/(m2.K)

查看答案

搜索结果不匹配？点我反馈

更多问题

A thermal insulating layer is attached to a hot plate. The side near the hot plate is at 230℃, and the other side is at 40℃. the thickness of the layer is 30 mm and the conductivity is 0.2W/(m.K). The ambient temperature is 20℃, and the convective heat transfer cofficient should be?

A. 105 W/(m2.K)
B. 63 W/(m2.K)
C. 12 W/(m2.K)
D. 51 W/(m2.K)

查看答案

Which of the following value is the critical value to determine whether the heat exchanger is compact heat exchanger or not?

A. 500 m2/m3
B. 600 m2/m3
C. 700 m2/m3
D. 800 m2/m3

查看答案

Which of the following statements about boiling heat transfer is wrong:

According to whether the temperature of liquid body reaches the saturation temperature, boiling can be categorized into saturated boiling and subcooled boiling.
B. The heat is transferred from the heating surface to the boiling liquid through the combined heat conduction and convection.
C. Surface superheating is a prerequisite for boiling heat transfer.
D. The liquid outside the bubble does not need to be superheated to allow the bubble to exist and grow.

查看答案

Which of the following statements about dropwise condensation are correct:

A. The condensed liquid does not wet wall surface well.
B. A portion of wall surface area is directly exposed to the vapor, so it has a smaller thermal resistance than film condensation.
C. It has strong heat transfer capacity, and heat transfer coefficient can be as high as hundreds of thousands.
D. It is difficult to produce and maintain for a long time on general metal surfaces.

查看答案

A. 8050 W/(m2.K) B. 7300 W/(m2.K) C. 3225 W/(m2.K) D. 125 W/(m2.K)

A thermal insulating layer is attached to a hot plate. The side near the hot plate is at 230℃, and the other side is at 40℃. the thickness of the layer is 30 mm and the conductivity is 0.2W/(m.K). The ambient temperature is 20℃, and the convective heat transfer cofficient should be?

Which of the following value is the critical value to determine whether the heat exchanger is compact heat exchanger or not?

Which of the following statements about boiling heat transfer is wrong:

Which of the following statements about dropwise condensation are correct:

A. 8050 W/(m2.K)
B. 7300 W/(m2.K)
C. 3225 W/(m2.K)
D. 125 W/(m2.K)