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Gary Turner Profile picture
Gary Turner
@DtaGuy
Solid state physicist (retired). Born at 309 ppm CO2. Same handle on the 🦋, where I plan to post in future as well as here. Follow ≠ approval.
May 4 • 15 tweets • 6 min read
Finally! I built & tested an open-source concept model air purifier that should be good for schools. Lots of air (CADR > 420 CFM), quiet (<45 dBA), uses <9 W, and ‘cause it’s wall-mounted & down-blowing, it moves air in the right direction & takes up no floor space.👀my ALTs🧵⬇️ Image shows a SketchUp view of the concept model. It uses four 24x24x1” 3M Filtrete 1900 MERV13 filters in an M configuration, above eight down-blowing 140mm Arctic P14PWM fans. (Shows simplified fan bodies, but not blades ‘cause that was easier to model.) Configuration is important. Warm human aerosol rises toward the ceiling. The idea is to scavenge warm, dirty air from the ceiling, filter it, & blast it down along the wall, where it can spread out over the floor & convect back up past the occupants’ faces. See ALT for more. Notional diagram showing warm upward flow from occupants and forced downward flow of filtered air. (I’d love to see a simulation of this in CFD). Room shown is 25’ wide x 20’ deep by 12’ high, containing 20 students and a teacher. Two units would give 8.5 ACH and 40.3 CFM/person, not even counting deposition on walls and existing HVAC. A ceiling fan in the middle of the room (pulling air up) would probably help by improving mixing, complementing this flow. HVAC and people moving around will add to this flow, of course, but something like this would still be present.
Nov 15, 2023 • 18 tweets • 4 min read
I built a spreadsheet to calculate the operating point of a combination of filters and fans in a #corsirosenthalbox. The Link is a few tweets down in the thread. It might have inappropriate extrapolations or other errors, but I hope it will help designers configure boxes. 1/🧵 A screenshot of the data entry spreadsheet. You enter number of filters of each type and size in the light blue fields, and number of fans of each type in the light green fields. The spreadsheet shows the operating point where the curves intersect. Tech types, please look at 2nd sheet (1900 Fltr Anlyss) to see what I did & what needs fixing. @CorsIAQ @JimRosenthal4 @robwiss @joeyfox85 @DavidElfstrom @cleanairkits @CRBoxKits @CleanAirStars @RFantinatto @open_erv @haussamen @sameo416 @syntagmatic @PlasticFull @leanhealth 2/ A screenshot of the second sheet of the workbook (1900 Fltr Anlyss) where I describe my method of curve fitting and extrapolating from one size filter to another.
Nov 19, 2022 • 15 tweets • 7 min read
For an upcoming family event, I wanted a powerful, quiet #CorsiRosenthalBox that could be collapsed to carry in the car. I started with a @robwiss format of 9 Arctic P14 PC fans with 4 20x20x1 Filtrete MERV13 filters. @CorsIAQ @JimRosenthal4 @PlasticFull @haussamen /1. Collapsed CR Box. I used Filtrete 1900s which are very similar to his Filtreet 2200s, so I'm hoping for performance similar to what he measured (556CFM CADR, 44.5dBA noise). Collapsed it's 21.5x21.5x5.5" and weighs 17 lb. Expanded it's 24.2" high. /2. Expanded CR Box with 125VAC-12VDC power supply.