Air is constantly being recirculated throughout the ME Building. In the summer that air is also cooled, using chilled water supplied by the South Power Plant. A schematic of such a system is shown below, along with photographs of actual hardware housed in the ME Building (its location is top secret).
Consider first air flowing through the fan/blower. It enters the fan from a plenum, where its velocity is essentially zero, and exits into a rectangular duct whose dimensions are 24 times 36 inches. The target flow rate is 800 scfm (scfm - standard cubic feet per minute, with standard implying 77 F and 1 standard atm). While flowing through the blower the air temperature can be approximated as constant; the pressure rises by 2 inches of water.
What is the air velocity in the duct? Report your answer in ft/s.
What is the air mass flow rate in lb m/sec?
What fan power is required to provide this flow?
Report your answer in hp. If the fan is 90 % efficient, what motor power is required? Again, report your answer in hp.