Square plates freshly sprayed with an epoxy paint must be

Chapter , Problem 12.91

(choose chapter or problem)

Square plates freshly sprayed with an epoxy paint must be cured at for an extended period of time. The plates are located in a large enclosure and heated by a bank of infrared lamps. The top surface of each plate has an emissivity of 0.8 and experiences convection with a ventilation airstream that is at T 27 C and provides a convection coefficient of h 20 W/m2 K. The irradiation from the enclosure walls is estimated to be Gwall 450 W/m2 , for which the plate absorptivity is wall 0.7. (a) Determine the irradiation that must be provided by the lamps, Glamp. The absorptivity of the plate surface for this irradiation is lamp 0.6. (b) For convection coefficients of h 15, 20, and 30 W/m2 K, plot the lamp irradiation, Glamp, as a function of the plate temperature, Ts, for 100 Ts 300 C. (c) For convection coefficients in the range from 10 to 30 W/m2 K and a lamp irradiation of Glamp 3000 W/m2 , plot the airstream temperature T required to maintain the plate at Ts 140 C. 12.92 A