Steam in a heating system flows through a 1-m long tube whose outer diameter is D1 = 3 cm andwhose walls are maintained at a temperature of Tb = 120 °C. Circular fins (k = 46 W/m. °C) of outer diameter D2 = 6 cm and constant thickness t = 2 mm are attached to the tube, as shown in the figure. 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 Tꚙ = 20 °C, with a combined heat transfer coefficient of h = 90 W/m2. °C. Determine:a. No fin area: Ano fin = ____ m2b. Unfin area: Aunfin = ____ m2c. Fin area: Afin = _______ m2d. Fin efficiency = ______e. Qno,fin = ______ Wf. Qtotal, fin = ______ Wg. Overall fin effectiveness =
Steam in a heating system flows through a 1-m long tube whose outer diameter is D1 = 3 cm and
whose walls are maintained at a temperature of Tb = 120 °C. Circular fins (k = 46 W/m. °C) of outer diameter D2 = 6 cm and constant thickness t = 2 mm are attached to the tube, as shown in the figure. 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 Tꚙ = 20 °C, with a combined heat transfer coefficient of h = 90 W/m2. °C. Determine:
a. No fin area: Ano fin = ____ m2
b. Unfin area: Aunfin = ____ m2
c. Fin area: Afin = _______ m2
d. Fin efficiency = ______
e. Qno,fin = ______ W
f. Qtotal, fin = ______ W
g. Overall fin effectiveness =
Given:
diameter D1 = 3 cm = 0.03 m
Radius r1 = 1.5 cm = 0.015 m
Circular fins (k = 46 W/m. °C) of outer diameter D2 = 6 cm = 0.06 m
radius r2 = 3 cm = 0.03 m
The space between the fin is S = 3 mm = 0.003 m
Lenght of tube is L = 1 m
Tube thichness t = 2 mm = 0.002 m
Solution:
a) No fin area i.e. Anofin =?
Where there are no fins attached to the tube, the heat transfer per meter length can be determined using Newton's law of cooling as follows:
The heat transfer (Qnofin) would be;
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