Engineering Board Exam Reviewer · Thermodynamics · hard
A small surface ( = 0.8, A = 0.5 m2) at 400 K is surrounded by large walls at 300 K. What is the net radiation heat transfer from the surface? ( = 5.67 × 10-8 W/m2· K4)
- 2.3 W
- 396.9 W
- 496.1 W
- 580.6 W
Answer
B. 396.9 W
Solution
q = A(Ts4 - Tsurr⁴) = 0.8(5.67 × 10-8)(0.5)(4004 - 3004) = 396.9 W. (Note: (T1 - T2)4 T14 - T24.)
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