The wall of a refrigerator is constructed of fiberglassinsulation (k = 0.035 W/m·K) sandwiched between two layersof 1-mm-thick sheet metal (k = 15.1 W/m·K). The refrigeratedspace is maintained at 3°C, and the average heat transfercoefficients at the inner and outer surfaces of the wall are4 W/m2·K and 9 W/m2·K, respectively. The kitchen temperatureaverages 25°C. It is observed that condensation occurson the outer surfaces of the refrigerator when the temperatureof the outer surface drops to 20°C. Determine the minimumthickness of fiberglass insulation that needs to be used in thewall in order to avoid condensation on the outer surfaces.

The wall of a refrigerator is constructed of fiberglassinsulation (k = 0.035 W/m·K) sandwiched between two layersof 1-mm-thick sheet metal (k = 15.1 W/m·K). The refrigeratedspace is maintained at 3°C, and the average heat transfercoefficients at the inner and outer surfaces of the wall are4 W/m2·K and 9 W/m2·K, respectively. The kitchen temperatureaverages 25°C. It is observed that condensation occurson the outer surfaces of the refrigerator when the temperatureof the outer surface drops to 20°C. Determine the minimumthickness of fiberglass insulation that needs to be used in thewall in order to avoid condensation on the outer surfaces.

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.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.38P: 2.38 The addition of aluminum fins has been suggested to increase the rate of heat dissipation from...

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Question

The wall of a refrigerator is constructed of fiberglass
insulation (k = 0.035 W/m·K) sandwiched between two layers
of 1-mm-thick sheet metal (k = 15.1 W/m·K). The refrigerated
space is maintained at 3°C, and the average heat transfer
coefficients at the inner and outer surfaces of the wall are
4 W/m2·K and 9 W/m2·K, respectively. The kitchen temperature
averages 25°C. It is observed that condensation occurs
on the outer surfaces of the refrigerator when the temperature
of the outer surface drops to 20°C. Determine the minimum
thickness of fiberglass insulation that needs to be used in the
wall in order to avoid condensation on the outer surfaces.

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