Chapter 11 FUNDAMENTALS OF THERMAL RADIATION
Chapter 11 FUNDAMENTALS OF THERMAL RADIATION
Chapter 11 FUNDAMENTALS OF THERMAL RADIATION
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<strong>Chapter</strong> <strong>11</strong> Fundamentals of Thermal Radiation<strong>11</strong>-34 A small surface emits radiation. The rate of radiation energy emitted through a band is to bedetermined.60Assumptions Surface A emits diffusely as a blackbody.Analysis The rate of radiation emission from a surface per unit surfacearea in the direction (,) is given asdQedE I e ( ,)cossin dddAThe total rate of radiation emission through the bandbetween 60 and 45 can be expressed asE2 060e 45I ( ,) cossin dd Ib T4 4 T4 4since the blackbody radiation intensity is constant (I b = constant), and260cossin 2 0 d d 456045cossin d (sin4260sin245) / 4Approximating a small area as a differential area, the rate of radiation energy emitted from an area of 1 cm 2in the specified band becomes45A = 1 cm 2T = 1500 KQ eT EdA 44(5.6710dA 82W/m K44)(1500K)4(<strong>11</strong>042m ) 7.18 W<strong>11</strong>-15
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