Question

See the rectangular fin below. Calculate the heat transfer rate through the wall, q, given the following: h = 15 W/m²K, Tg = 100°C, T = 25°C, and ka = 40 W/mK, Lq = 0.1 m, nf = 0.91, Ap = 0.05 m², Af = 0.1 m2 A = 0.1 m². 3h, (A) 670.5 W (B) 240.5 W (C) 3000 W (D) 548 W

Answer 1

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h. To ka L Let the temperature On the right side of the wall be Two The heat transfer rate of which is going into the wall will be equal to the heat carried away by fine + due to convection (the surface where fin is not present) Mathematically, it will given as 9 = KaACTs -Tw) or from fouriers law of conduction / La 7 q - KAIT Heat carried away by fir will be given as, V fin = fin h. Afin (Tw-To) This the heat carried away by single fin. But we are having 6 fine. Hence, (Q fin) total = 6x tin xh x Af X (Tw-Too) = 6 x 0.91X ISX 0.1 X (Tw-298) = 8.19 (Tw-298) The heat convected by the wall will be given as of it will will be there because on the area Ab it is coming in contact with the fluid (h= 15 w/onk) }

convected a = - т т т т т (9) = KAь (Т-То) - Isx 0.05x ( то - 298 ) = 0.75 СТ- 29 8) So, the equation becomes Ka A (Te-Tou) - (I fin) total + (4) convected La 40xox (373-Т%) = 8- 19 (To - 248) + 0-3S (T. -248) ди 40 (373 -То) = 8-94 (Т. - 248) А. 443 (373 -то) - (T – 248) 1668-9239 - 4.4743То To - 248 1966 - 3139 = s. 4743 То Ты - 3ѕ92996 K| We know that , 9. К А (Тя - То) = 40Хоих (373 -359-2946) р 19 = 54 8 - 016 La Correct Answer will be option 0 548 W/