hwk12_sol - ME 410 Spring 2008 Homework 12 Due: April 15,...

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ME 410 Spring 2008 Homework 12 Due: April 15, 2008 1. Determine the radiation heat transfer for a red-hot poker at 1200 K in the following wavelength ranges a.) the black body emissive power in the infrared region of the spectrum, 0.76 µ m < λ < 100 µ m b) the black body emissive power in the visible region of the spectrum, 0.40 µ m < λ < 0.76 µ m a.) The emissive power in the infrared range is given by E b,infrared = (f 100 -f 0.76 ) σ T 4 Going to the table of black body functions we find at λ =0.76, λ T = (0.76)(1200) = 912, f λ = 1.87 x 10 -4 at λ =100, λ T = (100)(1200) = 120,000, f λ = 1.0 and E b,infrared = (1.0 – 1.87 x 10 -4 )(5.67 x 10 -8 )(1200) 4 = 117551 W/m 2 b.) The emissive power in the visible range is given by E b,visible = (f 0.76 -f 0.40 ) σ T 4 with at λ =0.40, λ T = (0.40)(1200) = 480, f λ = 0 Then E b,visible = (1.87 x 10 -4 - 0)(5.67 x 10 -8 )(1200) 4 = 21.99 W/m 2 2. A new transparent material has been proposed as the cover for a fireplace opening. If the fire may be treated as a blackbody at 950 K, determine the
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hwk12_sol - ME 410 Spring 2008 Homework 12 Due: April 15,...

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