Question

6. Problem 3 (20 points): A Steam in a heating system flows through tubes whose outer diameter is 3 cm and whose walls are maintained at a temperature of 120°C. Circular aluminum alloy fins (k = 180 W/m.) of outer diameter 6 cm and constant thickness t 2 mm are attached to the tube, as shown in the figure below. The space between the fins is 3 mm, and thus there are 200 fins per meter length of the tube. Heat is transferred to the surrounding air transfer coefficient of 60 W/m2.K. Determine: a) The fin efficiency b) The fin Effectiveness 25°C, with a combined heat at 1.Sc) The rate of heat transfer, qt, from the tube per meter of its length as a result of adding fins, and d) The fin array effectiveness given by &f array 6. Problem 3 (20 points): A Steam in a heating system flows through tubes whose outer diameter is 3 cm and whose walls are Circular aluminum alloy fins (k = 180 W/m.) of outer diameter 6 cm and constant thickness t 2 mm are attached to the tube, as shown in the figure below. The space between the fins is 3 mm, and thus there are 200 fins per meter length of the tube. Heat is transferred to the surrounding air at 25°C, with a combined heat transfer coefficient of 60 W/m2.K. Determine: a) The fin efficiency b) The fin Effectiveness maintained at a temperature of 120°C. - 1.S e) The rate of heat transfer, qt, from the tube per meter of its length a result of adding fins, and d) The fin array effectiveness given by Ef array 4t dtunfin r,1.5 cm -3 cm 2 カrt フw AI T h t-2 mm Ac-2 7rt P27 S 3 mm -A2.919 194メ2オrt AX 100 12.4 19x2 Antin (T-T heAN nA. CTO-T 3.92 KP nA c An T.-90)/L93: 22 Wlm

Answer 1

GNen 1 A no Fin DL T O 03m 1 m a aq42 m Uaa ou 60 * 00qy2 *(120 - 25) hAno Fen ( T bas e -' 53 w L o 5 (DFln -o5(006- o03) O O15 Fn yadfUs + O03 .00a| a) = O.03 I Lc = L+ Th°cKnesg ( &) (O-008a) O 015 + 0.016m Am Lc t = 0 16 o.00A cs Scanned with CamScanner - O co09 m

2 1 80 0 Xube (o. o1) LG 180 o O0 0032 KAM O a0 (graph) F91om A Fen C910.0)0- O OO468 y m hA Fn Tbase O 9660o o046a4( 1ao - a5) A aAun Fln DS = AO.0 3 O 00 E O.d00 o A 83 m2 h Aun Fen (Tbas e - 60 0 000 & 83 (120-25) Scanned with CS CamScanner

Fen 3 (9 3 95.3 5 3 0-04才 (usunus )u- ( A00( 95.3 t l 6) 5380 5380 16 Eay こ30362.5 CS anned with CamScanner