Square plates freshly sprayed with an epoxy paint must be cured at 140°C 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 G wall = 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 (c) For convection coefficients in the range from 10 to 30 W/m2 ? K and a lamp irradiation of Clamp = 3000 W/m2, plot the airstream temperature T? required to maintain the plate at Ts = 140°C.

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Enclosure Ventilation airstream Lamp T. h = Game Painted plate