Steam at 200°C flows in a cast iron pipe (k = 80 W/m-°C) whose inner and outer diameters are D, = 0.20 m and D2 = 0.22 m. The pipe is exposed to room air at 30°C. The heat transfer coefficients at the inner and outer surfaces of the pipe are 75 and 30 W/m2.°C, respectively. The pipe is to be covered with 2.6 cm-thickness glass wool insulation (k = 0.05 W/m-°C) to decrease the heat loss from the steam. The percentage decrease in heat loss from the steam due to insulation is . . %. Select one: O a. 95.1 b. 94.0 X O c. 93.2 O d. 92.5 O e. 90.7

Steam at 200°C flows in a cast iron pipe (k = 80 W/m-°C) whose inner and outer diameters are D, = 0.20 m and D2 = 0.22 m. The pipe is exposed to room air at 30°C. The heat transfer coefficients at the inner and outer surfaces of the pipe are 75 and 30 W/m2.°C, respectively. The pipe is to be covered with 2.6 cm-thickness glass wool insulation (k = 0.05 W/m-°C) to decrease the heat loss from the steam. The percentage decrease in heat loss from the steam due to insulation is . . %. Select one: O a. 95.1 b. 94.0 X O c. 93.2 O d. 92.5 O e. 90.7

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter7: Forced Convection Inside Tubes And Ducts

Section: Chapter Questions

Problem 7.24P

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Concept explainers

Conduction and Convection

When energy travels from one object to another it is said to have undergone heat transfer. Heat transfer is nothing but the transfer of thermal energy or internal energy from one thing to another, like e.g., when a vessel with water, kept on top of a burner, heats up because of the flame underneath it.

Question

Steam at 200°C flows in a cast iron pipe (k = 80 W/m-°C) whose inner and outer diameters are D, = 0.20 m and D, = 0.22 m. The pipe is
exposed to room air at 30°C. The heat transfer coefficients at the inner and outer surfaces of the pipe are 75 and 30 W/m2.°C,
respectively. The pipe is to be covered with 2.6 cm-thickness glass wool insulation (k = 0.05 W/m-°C) to decrease the heat loss from the
steam. The percentage decrease in heat loss from the steam due to insulation is ..
%.
Select one:
O a. 95.1
b. 94.0 X
c. 93.2
d. 92.5
e. 90.7

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