Question

Conditioned air at 1 atm and approximately 12C is to be transported via a circular duct at 0.3 m^3/s. The distance between the air conditioner and the space to be conditioned is 50 m. The fan capacity limits the head loss to a maximum of 300 m of air. Find the minimum diameter of the duct. Hint: Guess a diameter, from which you can deduce the average velocity. Then, based on the Reynolds number, and the roughness (based on the typical material, e.g., aluminum, commercial steel), obtain the friction factor. If the head loss is much less than the maximum, you have probably oversized the duct. In this case, reiterate with a smaller diameter. If the head loss is larger than the maximum, go up to the next duct size, and repeat the calculations.

Answer 1