An opaque, diffuse, gray, square (200 mm x 200 mm) plate with an emissivity of 0.8 is placed over the opening of a furnace (L = 200 mm) and the plate temperature is known to be 400 K at a certain instant. The bottom of the furnace, having the same dimensions as the plate, is black and operates at 900 K. The sidewalls of the furnace are well insulated. The top of the plate is exposed to ambient air with a convection coefficient of 25 W/m²-K and to large surroundings. The air and surroundings are each at 300 K. Tsur T Air h Plate -Insulated sidewalls -Furnace bottom (a) Evaluate the net radiative heat transfer to the bottom surface of the plate, in W. 91 i W (b) If the plate has mass and specific heat of 2 kg and 900 J/kg-K, respectively, what will be the change in temperature of the plate with time, dT,/dt, in K/s? Assume convection to the bottom surface of the plate to be negligible. dT, = i dt K/s

An opaque, diffuse, gray, square (200 mm x 200 mm) plate with an emissivity of 0.8 is placed over the opening of a furnace (L = 200 mm) and the plate temperature is known to be 400 K at a certain instant. The bottom of the furnace, having the same dimensions as the plate, is black and operates at 900 K. The sidewalls of the furnace are well insulated. The top of the plate is exposed to ambient air with a convection coefficient of 25 W/m²-K and to large surroundings. The air and surroundings are each at 300 K. Tsur T Air h Plate -Insulated sidewalls -Furnace bottom (a) Evaluate the net radiative heat transfer to the bottom surface of the plate, in W. 91 i W (b) If the plate has mass and specific heat of 2 kg and 900 J/kg-K, respectively, what will be the change in temperature of the plate with time, dT,/dt, in K/s? Assume convection to the bottom surface of the plate to be negligible. dT, = i dt K/s

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.

Chapter11: Heat Transfer By Radiation

Section: Chapter Questions

Problem 11.65P

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