Problem

b) A steel pipe with heat transfer coefficient of 42 W/mK contains flowing water. The outer diameter of the pipe is 90 mm and the wall thickness is 3 mm. Calculate:
i. The heat loss by convection and conduction per meter length of un-insulated pipe when the water temperature is 14C, the outside air temperature is 10C, the water side heat transfer coefficient is 30KW/m2 K and the outside heat transfer coefficient is 20KW/m2 K.

Answer

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Answer

33.58 W/m is the heat loss by convection and conduction per meter length of un-insulated pipe.

Steps

Step 1 :Calculate the inner diameter of the pipe: D_inner = D_outer - 2 * t = 0.09 - 2 * 0.003 = 0.084 m

Step 2 :Calculate the area of the pipe's inner surface and outer surface per meter length: A_inner = π0.084 m, A_outer = π0.09 m

Step 3 :Calculate the heat loss by convection and conduction: Q = 30000π0.084(14(10))+42π0.09(14(10))20000π0.09+42π0.084 W/m

Step 4 :33.58 W/m is the heat loss by convection and conduction per meter length of un-insulated pipe.

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