How should the blades of the outside air damper and return air damper be arranged to thoroughly mix the air?

How should the blades of the outside air damper and return air damper be arranged to thoroughly mix the air?

• A. The air streams collide
• B. The air streams flow in parallel
• C. The streams are kept separate
• D. There is no mixing

Answer: (A)

Thorough mixing of outside air and return air relies on creating turbulence by making the two air streams meet head-on. When the blades are arranged so the streams collide, their jets interact strongly, generating vortices and turbulent motion that blend the air properties—temperature, humidity, and contaminants—more uniformly. This collision disrupts each stream’s momentum and promotes thorough mixing before the air proceeds to filtration and distribution. If the streams flow in parallel, they tend to ride side by side with limited interaction, leading to uneven properties and poor mixing. Keeping them completely separate prevents any exchange, which defeats the purpose of mixing. So, colliding air streams is the arrangement that best achieves thorough mixing.

Thorough mixing of outside air and return air relies on creating turbulence by making the two air streams meet head-on. When the blades are arranged so the streams collide, their jets interact strongly, generating vortices and turbulent motion that blend the air properties—temperature, humidity, and contaminants—more uniformly. This collision disrupts each stream’s momentum and promotes thorough mixing before the air proceeds to filtration and distribution.

If the streams flow in parallel, they tend to ride side by side with limited interaction, leading to uneven properties and poor mixing. Keeping them completely separate prevents any exchange, which defeats the purpose of mixing. So, colliding air streams is the arrangement that best achieves thorough mixing.