1 a) The hot combustion gases of a furnace are separated from the ambient air and its surroundings, which are at 25°C, by a brick wall 0.15 m thick (Figure la). The brick has a thermal conductivity of 1.2 W/m K and a surface emissivity of 0.8. Under steady-state conditions an outer surface temperature of 100°C is measured. Free convection heat transfer to the air adjoining the surface is characterized by a convection coefficient ofh = 20 W/m².K. What is the brick inner surface temperature? b) Consider steady-state conditions for one-dimensional conduction in a plane wall having a thermal conductivity k = 50 W/mk and a thickness L = 0.25 m, with no internal heat generation. Determine i) the heat flux and the unknown quantity for each case; and ii) sketch the temperature distribution, indicating the direction of the heat flux. Case T:(°C) T2(°C) dT/dx (K/m) ġ(W/m²) 1 50 -20 70 160 3 40 -80

1 a) The hot combustion gases of a furnace are separated from the ambient air and its surroundings, which are at 25°C, by a brick wall 0.15 m thick (Figure la). The brick has a thermal conductivity of 1.2 W/m K and a surface emissivity of 0.8. Under steady-state conditions an outer surface temperature of 100°C is measured. Free convection heat transfer to the air adjoining the surface is characterized by a convection coefficient ofh = 20 W/m².K. What is the brick inner surface temperature? b) Consider steady-state conditions for one-dimensional conduction in a plane wall having a thermal conductivity k = 50 W/mk and a thickness L = 0.25 m, with no internal heat generation. Determine i) the heat flux and the unknown quantity for each case; and ii) sketch the temperature distribution, indicating the direction of the heat flux. Case T:(°C) T2(°C) dT/dx (K/m) ġ(W/m²) 1 50 -20 70 160 3 40 -80

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.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.57P

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