Question

Calculate the heat losses that are transferred to the open air of 1m from an uninsulated pipe with diameter d1 (inner diameter = 150 mm) and d2 (outer diameter = 165 mm) when water with an average temperature T1 runs through it. = 90 ° C and the ambient temperature Ta = -15 ° C. The coefficient of thermal conductivity of the tube material is K = 50 W / m ° C. The heat transfer coefficient for water and tube is 1000 W / m2 ° C and that for tube and environment is 12 W / m2 ° C. Consider steady state (50 points)
Also determine the temperatures on the inner and outer surfaces of the tube. (50 points)

Т2 - Tз Т1; T4 T10 W от4 Т2 T3

Answer 1

hi = 1000 w/moc. L = im d = Iso mm = 0.15m 0.075 m 12 T4- d₂ 165 mm 0.165m T Y₂ 0.0 825 m T = 90°c T Ta am Tag Ta - 15 °c 4 in (7/6) K = so w/moc HiA hat 25KL Thermal cirwit. ha = 12 W/m²oc Heat Transffer (0) = (T, TA) + ㅗ h: А: + ha Az 2KKL 90 - (-15) In 0.0825 + es ) 0.075 1000x 2 xxxx, xL 12x + x 2 x V x L 2x4xsOXI 105 Q = 1 + In 0.0825 0.075 1 2000X AX 0.045 + 248A X 0.0825 100x T

Heat transfer D 6 4 3.4296 Walt Steady stale 28 - hi Ai - 643.4296 = 9o Te - 1000 X 2X KX 0.0 SX T T₂ = 88.6346 oc 1 T3- T4 hax Az 64 3.4296 = Tz + 15 12 x 2 x* x 0. 0825 x1 To 88.4394 °C