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Que. A steel pipe of 20 mm inner diameter and 2 mm thickness is covered with 20 mm thick of fiber glass insulation (k = 0.05 W/m degree). If the inside and outside convective coefficients are 10 W/m² degree and 5 W/m² degree, calculate the overall heat transfer coefficient based on inside diameter of pipe. In the diagram, the diameter of small circle is 20 mm
a. 1.789 W/m² degree
b. 2.789 W/m² degree
c. 3.789 W/m² degree
d. 4.789 W/m² degree
Correct Answer:2.789 W/m² degree
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