Discuss the following:
Q: Atmospheric air enters a100-m-long, 150-mm-diameter uninsulated heating duct at 60°C and 0.04 kg/s. The duct surface temperature is approximately constant at Ts = 15°C.
(a) What are the outlet air temperature, the heat rate q, and pressure drop ?p for these conditions?
(b) To illustrate the tradeoff between heat transfer rate and pressure drop considerations, calculate q and ?p for diameters in the range from 0.1 to 0.2 m. In your analysis, maintain the total surface area. As = pDL, at the value computed for part (a) Plot q, ?p and L as a function of the duct diameter.