philipn authored on Aug. 26, 2021, 3:01 p.m. | | Additions are marked like this |
This is a "scratch" page used to record various measurements and test results obtained for the Corsi-Rosenthal Cube. Room sizing / CADR figureCFM measurements of a 4-sized cube configuration were taken here: https://twitter.com/JohnSemmelhack/status/1313855226844151808 As per conversation with David Elfstrom, these figures were using a Lasko Power Plus fan, which puts out ~20% more flow than typical fan. In David Elfstrom's own CADR predictions, he uses a figure of \(\sim62\%\) efficacy of the MERV-13 filters (confirmed with him). So this is a figure based on \(0.3um\) particles expected lower bound performance with the MERV-13 filters. COVID-carrying particles are likely larger than 0.3um (most penetrating particle size), so this is a lower bound figure. I am not sure if the exact size distribution of COVID-carrying particles is known. We know \(80\%\) of them are are "less than \(5um\)." Using John Semmelhack's CFM measurements, we can make a guess at the difference between the cube with 1" filters and the cube with 2" filters. His cube was constructed with 2" MERV-13 filters. We assume a conservative figure here. Want to give a lower bound. So this scale multiple looks like \((349/455)\). \((349/455)*871*0.62*0.80 = 331 \text{ CFM CADR}\). | This is a "scratch" page used to record various measurements and test results obtained for the Corsi-Rosenthal Cube. Room sizing / CADR figureCFM measurements of a 4-sized cube configuration were taken here: https://twitter.com/JohnSemmelhack/status/1313855226844151808 As per conversation with David Elfstrom, these figures were using a Lasko Power Plus fan, which puts out ~20% more flow than typical fan. In David Elfstrom's own CADR predictions, he uses a figure of \(\sim62\%\) efficacy of the MERV-13 filters (confirmed with him). So this is a figure based on \(0.3um\) particles expected lower bound performance with the MERV-13 filters. COVID-carrying particles are likely larger than 0.3um (most penetrating particle size), so this is a lower bound figure. I am not sure if the exact size distribution of COVID-carrying particles is known. We know \(80\%\) of them are are "less than \(5um\)." Using John Semmelhack's CFM measurements, we can make a guess at the difference between the cube with 1" filters and the cube with 2" filters. His cube was constructed with 2" MERV-13 filters. We assume a conservative figure here. Want to give a lower bound. So this scale multiple looks like \((349/455)\). \((349/455)*871*0.62*0.80 = 331 \text{ CFM CADR}\). Fan shroud added As per David Elfstrom's measurements, an optimally-sized fan shroud increases the fan flow by \(47\%\). We should assume that not everyone gets the exact optimal fan shroud sizing (due to differences in fan models), so let's lower this by \(20\%\) to \(37.6\%\): \(331 * 1.376 = 455 \text{ CFM CADR}\) |
