3.5 A dormitory at a large university, built 50 years ago, has exterior walls constructed of L, = 25-mm-thick sheath- ing with a thermal conductivity of k, = 0.1 W/m.K. To reduce heat losses in the winter, the university decides to encapsulate the entire dormitory by applying an L₁ = 25-mm-thick layer of extruded insulation charac- terized by k, = 0.029 W/m K to the exterior of the original sheathing. The extruded insulation is, in turn, covered with an Lg = 5-mm-thick architectural glass with kg = 1.4 W/m K. Determine the heat flux through the original and retrofitted walls when the interior and exterior air temperatures are T,i = 22°C and To,o= -20°C, respectively. The inner and outer convection heat transfer coefficients are h; = 5 W/m² K and h 25 W/m².K, respectively. . =

3.5 A dormitory at a large university, built 50 years ago, has exterior walls constructed of L, = 25-mm-thick sheath- ing with a thermal conductivity of k, = 0.1 W/m.K. To reduce heat losses in the winter, the university decides to encapsulate the entire dormitory by applying an L₁ = 25-mm-thick layer of extruded insulation charac- terized by k, = 0.029 W/m K to the exterior of the original sheathing. The extruded insulation is, in turn, covered with an Lg = 5-mm-thick architectural glass with kg = 1.4 W/m K. Determine the heat flux through the original and retrofitted walls when the interior and exterior air temperatures are T,i = 22°C and To,o= -20°C, respectively. The inner and outer convection heat transfer coefficients are h; = 5 W/m² K and h 25 W/m².K, respectively. . =

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 2.24P

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