Problem 1: A thin-walled metallic tube of length 1 m and inside diameter 3 mm has water flowing through it at a mass flow rate of 0.01 kg/s and a mean inlet temperature of 97°C. Assume that the average temperature for property evaluation for all parts of this problem is 325K. (a) What is the outlet temperature of the water in the tube if the tube surface temperature can be maintained constant at 27°C? Ans: 33.7°C (b) If air blows around the pipe (perpendicular to the pipe axis) with a velocity of 10 m/s and a freestream temperature of 27°C, what is the outlet temperature of the water? (Hint: review the last part of Ch. 8.3.3;you can neglect the conduction resistance of the pipe wall and assume that because it is so thin, the inner diameter and outer diameter are essentially the same). Is this result surprising to you? Why do you think it is so different from part (a)? Partial Ans: 94.3°C

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