A heating contractor must heat 0.2 kg/s of water from 10C to 30C using hot air gas in cross flow over a thin-walled tube. Your assignment is to develop a design graph that can be used to specify the diameter of the pipe. Consider the range of the pipe diameter between 20mm and 50mm, the length of the pipe is 9m. The hot air stream temperature is T. = 380*, the air velocity is 30m/s. Hence, the problem is to determine the diameter which ensure 30C of the exit water flow