A cast-iron pipe of 0.11 m outer diameter (O.D.) and 0.10 m inner diameter (I.D.) carries...

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A cast-iron pipe of 0.11 m outer diameter (O.D.) and 0.10 m inner diameter (I.D.) carries steam at 200 °C. It is to be insulated with a 0.025 m thickness on an insulating material having Kkm = 0.035 W/m K. The ambient temperature is 0 °C and the outer and inner heat transfer coefficients are, respectively, 72 and 225 W/m². K. Thermal conductivity of cast-iron pipe is equal to 46 W/m. K. a) (15 pts.) Please compare the heat flux per unit length when the insulating material is placed on the inner surface and/or is placed on the outer surface. Why we observe such behavior? b) (15 pts.) What thickness of insulation, when placed on the outer surface, gives the same heat flux through the wall as a 0.025 m thickness placed on the inner wall? A cast-iron pipe of 0.11 m outer diameter (O.D.) and 0.10 m inner diameter (I.D.) carries steam at 200 °C. It is to be insulated with a 0.025 m thickness on an insulating material having Kkm = 0.035 W/m K. The ambient temperature is 0 °C and the outer and inner heat transfer coefficients are, respectively, 72 and 225 W/m². K. Thermal conductivity of cast-iron pipe is equal to 46 W/m. K. a) (15 pts.) Please compare the heat flux per unit length when the insulating material is placed on the inner surface and/or is placed on the outer surface. Why we observe such behavior? b) (15 pts.) What thickness of insulation, when placed on the outer surface, gives the same heat flux through the wall as a 0.025 m thickness placed on the inner wall?

Answer rating: 100% (QA)

SOLUTION To compare the heat flux per unit length when the insulating material is placed on the inner surface and when it is placed on the outer surface we need to calculate the heat transfer rate for ... View the full answer