Question

Part C In the spaces below perform the calculations requested that pertain to an air distribution system for a single family residence with a floor area of about 2,000 to 3,000 sq. ft. with an airflow of 1000cfm through the ducting, fan and HXs. Based on an air velocity of 15 ft/s, calculate the size of a square duct. Repeat for a rectangular duct with an aspect ratio of 2.0 ( width divided by height ). Also calculate the hydraulic diameter for both a. b. Assume a friction factor of 0.015 and calculate the pressure drop ( inches of water and psi) for 200 ft of ducting which could also include equivalent lengths in the case of minor losses being added in ). Calculate the ideal power for a fan to deliver this flow and for a real fan with an efficiency of 60%. Repeat these calculations for 600 ft of ducting c. Calculate a friction factor for both the square and rectangular duct and compare to the above. d. For a 3 ton A/C, what is the temperature drop through the evaporator?

Answer 1

Ar vrlocily in a ventilehon luct V,- air veloc (41)2 also widK 2.

doamft.丶Can be calculated a ai 2 2 (477+138.5) 2(3%)

V = mean vclocYY s-95 71365) -0.00130 8S3 (psi )

For Gso 952s r 0 0.004% 5471 PSI )

: 64 AJ