e4 Air is flowing at an average velocity of 2.5m/s through a smooth 0.1m-diameter copper tube that is submerged in a cool lake. The water in the lake is maintained at constant bulk temperature of 15C, with a heat transfer coefficient of 1000W/(m2.K). The air (1atm) enters the coppe tute temperature Te=20C a) Sketch the problem, and show all parameters - and list your assumptions. 14 marks b) By assuming the flow to be fully developed, calculate the heat transfer coefficient for the air inside the tube. clearly stating how you evaluate the fluid properties. Give your answer in units of W/(m2K). c) Taking the surface temperature Ts of the tube to be constant, calculate the length L of the tube. Hint: A maximum of two iterations is only needed; your answer should satisfy 5