The window of a large vacuum chamber is fabricatedfrom a

Chapter 12, Problem 12.75

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The window of a large vacuum chamber is fabricatedfrom a material of prescribed spectral characteristics.A collimated beam of radiant energy from a solar sim-ulator is incident on the window and has a flux of3000 W/m2. The inside walls of the chamber, whichare large compared to the window area, are maintainedat 77 K. The outer surface of the window is subjectedto surroundings and room air at 25C, with a convec-tion heat transfer coefficient of 15 W/m2?K.(a) Determine the transmissivity of the window mate-rial to radiation from the solar simulator, whichapproximates the solar spectral distribution.(b) Assuming that the window is insulated from itschamber mounting arrangement, what steady-statetemperature does the window reach?(c) Calculate the net radiation transfer per unit area ofthe window to the vacuum chamber wall, exclud-ing the transmitted simulated solar flux.