Team develops 'catch and kill' air filter
Marie Donlon | July 08, 2020A team from the University of Houston has developed a so-called “catch and kill” air filter that is capable of trapping and instantly killing SARS-CoV2 — the virus responsible for COVID-19.
Recognizing that the virus cannot survive temperatures above 70° C, the researchers heated porous nickel foam commonly used in air filters to 200° C. During testing, the heated filter reportedly killed 99.8% of SARS CoV2 following just one pass through the filter.
To develop the air filter, researchers folded the nickel foam and connected its different compartments to electrical wires, thereby increasing the material’s resistance in a bid to also raise its temperature to as much as 250° C. This enabled the air filter to electrically heat itself versus obtaining heat from an outside source, thereby reducing the amount of heat escape from the filter and, consequently, enabling the connected air conditioning system to operate with minimal resistance.
Performance of prototype device on aerosolized SARS-CoV-2 and Bacillus anthracis. Source:University of Houston
The filter, which also killed 99.9% of anthrax spores during testing, is intended for use in high-risk settings such as airports, airplanes, offices, schools and cruise ships, for instance, and reportedly satisfies the mandates of conventional heating, ventilation and air conditioning (HVAC) systems.
Additionally, the University of Houston team is developing desktop versions of the air filter to clean the air in the immediate vicinity of an office worker’s desk.
The air filter is detailed in the journal Materials Today Physics.
They say this heated filter doesn't add a lot of heat to the air, but show no statistics...so I have my doubts...I don't see how you can run air through a filter that is 250° and not add a great deal of heat to the air stream...This might be fine in the winter time, but adding an additional heat load on an existing A/C system, is not going to fly....and I would think that running virus laden air through a sweating evaporator coil would catch quite a few viruses, not to mention a HEPA rated filter...and I might add you can install a UVC light to shine on your evaporator....althou
In reply to #1
You could make the system regenerative as in a counterflow heat exchanger. I was wondering about using a peltier junction where the air is pulled past the hot side and discharged across the cold side.
In reply to #2
That could be rather energy intensive, peltier is not efficient, I mean watts per btu is added to the A/C cost, although that might be easier to retrofit, still would need some cost analysis...would need to calculate reliability and maintenance costs associated as well as design life.....If the unit was maintenance free and lasted for 20 years, then there might be a shot, if the price wasn't prohibitive...say 2 to 4 hundred...in residential sizes...
In reply to #3
You're right that the Peltier junction would not be economically justifiable for larger installations, but I thought it might be worth considering for a personal size unit. A main feature would be to filter the air coming in as well as the air coming out. I thought it interesting that a couple of months ago there was not much concern about filtering discharge air from ventilators.
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In reply to #4
Worth a look...resistance heat always carries a high electrical burden though...they are heating the filter in excess of 400°F...in a folded accordion type filter, that's a lot of area...I would just go with an activated charcoal canister. coming and going....
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