Radiant Heat Problems
transfer of heat problem im having trouble figuring it out?
A person eats a dessert that contains 220 Calories. (This “Calorie” unit, with a capital C, is the one used by nutritionists; 1 Calorie = 4186 J. See Section 12.7.) The skin temperature of a person is 36°C and that of her environment is 18°C. The emissivity of her skin is 0.75 and its surface area is 1.3 m2. How much time would it take for her to emit a net radiant energy from her body that is equal to the energy contained in this dessert?
T = 309.15 K, Tamb = 291.15 K
Radiant intensity I = σE(T^4-Tamb^4) = 82.873 w/m^2
Radiant power = IA = 149.17 w
Time = 220*4186/power = 6174 s
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