Topic: Heat Transfer
The temperature distribution across a 1m thick concrete wall is T = 150 - 80x + 16x². With k=0.6 W/mK and A=10 m², the heat accumulated in unit time is
- A. 768 J/sec
- B. 384 J/sec
- C. 96 J/sec
- D. 192 J/sec
Answer: D. 192 J/sec
Explanation: Heat accumulated = Heat in - Heat out. Heat flux q = -kA(dT/dx). dT/dx = -80+32x. q_in (at x=0) = -0.6 * 10 * (-80) = 480 W. q_out (at x=1) = -0.6 * 10 * (-80+32) = 288 W. Heat accumulated = 480 - 288 = 192 J/sec.