After modeling a cleanroom for this exercise, I applied the various conditions required to solve a computational fluid dynamics (CFD) test on the room. You can't see it from the video, but I have a main feed duct branching off to 4 HEPA filters feeding a room approximately 38' x 7'. On each long side of the room, there are 6 cold air returns feeding the air handler unit (AHU). Boundary conditions were set simply at a volume of 1,800 cubic feet per minute (CFM) being fed into the main duct with environmental conditions for the exit ducts and each HEPA filter is set as a porous medium.

In the following video named Velocity 1, you can see the flow captured by the elbow duct turning 90 degrees down into the HEPA filter and then on into the cleanroom, but clearly only 75% of the entire filter is being used looking at it from the side view. The air is packing up at the back of the duct and not flowing through the HEPA filter efficiently.

In the next video named Velocity 2, you can see the elbow duct position has been moved to try and improve the flow efficiency down into the HEPA filter. A logical change that you would think should help direct the flow across the entire filter, but it seems that the air flow still wants to pack up at the back of the filter leaving 25% of the HEPA unused.

In the final video named Velocity 3, you can see the elbow duct position has been retained but an internal cross shaped vane has been added within the elbow. Now we can see a much improved flow across the HEPA filter, utilizing 100% of the filter span with good laminar indication into the clean room.

To purchase your cleanroom or book your CFD time with Biologics Modular, contact Julian Karras directly here.

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