Question

Dr. Clark designed a system capable of cooling the air of a house using water in river. The main component is stainless steel pipe (k=15.1 W/mK, Di=0.15m Do=0.152m) submerged in a river with a water temperature T_fluid=17 C. The warm air from the house enters this cooling pipe at a volume flow rate 0.025 m3/s, and T_m,i=27 C. The exit temperature is expected to be T_m,o=20 C. The convection heat transfer coefficient between the pipe external surface and water is ℎ=1000W/m^2K.

(a) Please justify if you can assume the temperature of the external pipe surface is constant? (This is a general concept question which is not associated with (b) to (d).

(b)You can ignore the entrance length, please find the convection heat transfer coefficient h_i at internal surface.

(c) Please justify if you can ignore the thermal resistance associated with the conduction heat transfer through the stainless steel pipe and the convection heat transfer at external surface.

(d) Please find the length of the tube needed using either equation 8.43 or 8.45 b.You can assume the air flow in pipe is fully developed flow.

Answer 1

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