Problem #1: A composite wall is constructed from 2 cm stainless steel (k = 10 W/m.K), 5 cm c corkboard (k = 0.1 W/m.K) and 1cm of plastic (k = 0.01 W/m.K). a) Draw the thermal circuit for the steady state conduction through the wall. b) Evaluate the individual thermal resistance of each material layer. c) Determine the heat flux of the surface of steel is maintained at 100 C and the plastic surface is at 20 C. d) What are the temperatures on each side of the corkboard under these conditions?

Problem #1: A composite wall is constructed from 2 cm stainless steel (k = 10 W/m.K), 5 cm c corkboard (k = 0.1 W/m.K) and 1cm of plastic (k = 0.01 W/m.K). a) Draw the thermal circuit for the steady state conduction through the wall. b) Evaluate the individual thermal resistance of each material layer. c) Determine the heat flux of the surface of steel is maintained at 100 C and the plastic surface is at 20 C. d) What are the temperatures on each side of the corkboard under these conditions?

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 2.26P

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1.37 Mild steel nails were driven through a solid wood wall consisting of two layers, each 2.5-cm thick, for reinforcement. If the total cross-sectional area of the nails is 0.5% of the wall area, determine the unit thermal conductance of the composite wall and the percent of the total heat flow that passes through the nails when the temperature difference across the wall is 25°C. Neglect contact resistance between the wood layers.
1.63 Liquid oxygen (LOX) for the space shuttle is stored at 90 K prior to launch in a spherical container 4 m in diameter. To reduce the loss of oxygen, the sphere is insulated with superinsulation developed at the U.S. National Institute of Standards and Technology's Cryogenic Division; the superinsulation has an effective thermal conductivity of 0.00012 W/m K. If the outside temperature is on the average and the LOX has a heat of vaporization of 213 J/g, calculate the thickness of insulation required to keep the LOX evaporation rate below 200 g/h.
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