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A UV light system in an HVAC is the kind of game changer to effectively get ahead of infectious disease outbreaks. They make a system (kind of expensive) that also uses counterflow heat exchangers to bake the air to about 350 degrees to kill just about everything, then cools it back down to something normal, and recover most of the energy needed to do the heat up and cool down.
Essentially there are a pair of ducts with an oven at the far end. Pathogen laden air is drawn in one end. There is an accordian of copper or maybe copper clad aluminum, separating the two air streams. It has maybe half an acre of surface area so the hot air coming out of the oven, transfers its heat to the cool air going into it, while cooling off the super-hot air to near room temperature by the time it gets to the discharge point. Only a little refrigeration is needed to chill that down the last few degrees, and a little supplemental heat to pre-heat the intake air on the way to the oven. Sometimes they can use some of the a/c condenser core inside the intake to pre-heat for the oven, and make the process more energy efficient.
... A heat exchanger is a device that allows heat from a fluid (a liquid or a gas) to pass to a second fluid (another liquid or gas) without the two fluids having to mix together or come into direct contact. ...
... A recuperator is typically used to capture heat that would otherwise be lost, for example, as stuffy air is ventilated from a building: cold, incoming fluid is channeled in the opposite direction to warm, outgoing fluid to minimize the heat loss. The two fluids flow through separate channels, remain separate, and do not mix. Since incoming and outgoing fluids move in opposite directions, recuperators are examples of counterflow heat exchangers. The heat exchanger in a heat-recovery ventilation (HRV) system is an everyday example of a recuperator. ...
Phoenix in August? In the midst (more or less) of a pandemic?
It’s not but doesn’t have the humidity of the Southeast. If everything is indoors, it’s no different than it would be for people who live there. I’m sure it’s a financial decision. They need an area with hotel space available and it will bring money and temporary jobs to the area, or will bring laid off and furloughed employees back for the time. It seems extreme foe those looking at it politically but from a business standpoint, it makes sense. A lot of places opened on June 1st.
Everything is air conditioned plus unless the humidity is high, it doesn't feel so hot.
Oddly, we could all tell the difference in the air 'smell'? Can't explain, but there was a difference. And our portable air purifiers work less, and the filters stay cleaner longer. Since 80% of the area surrounding us is desert dirt, that's nice!
The issue for me is our numbers of cases are rising rapidly in all categories - new cases, new hospitalization and new deaths. Banner Health just closed ALL of their hospitals to Covid cases and restricted ER access and they are the largest hospital system here. A convention of 17,000 or more could be deadly.
Jeri (azpaints) said:
Oddly, we could all tell the difference in the air 'smell'? Can't explain, but there was a difference.
Probably ozone. Low levels of ozone is what gives that "fresh air" smell accompanying a thunderstorm, combined with the rain having swept a lot of dust out of the air.
Another device we used in the old days in Lubbock was an electrostatic air cleaner. They still use them in bars and other dwindling places where people are allowed to smoke, to yank the smoke particles out of the air.
It works by emitting electrons. These attach to air molecules, creating negatively charged ions. The atoms want to get rid of the extra electrons, but the only thing around are the surfaces of assorted particles suspended in the air. As these particles accumulate excess electric charge, they can be moved by electric fields.
In most of these devices they use about 30,000 volts or so to produce the electric charge difference. There is this "fuzz" that is metal made where it has millions of tiny spikes, where the surplus electrons build up and are squeezed out into the surrounding air. A few inches away are some metal plates that either are at ground or at a fairly high positive potential.
The surplus electrons are attracted to the relatively positive collection plates, and since they have become attached to the smoke particles, they are drawn to the plates just like fine bits of paper are drawn to a comb after you rub it on the cats' fur.
The net current is relatively low, a few microamps at the most, but it quickly pulls an incredible amount of smoke out of the air that is drawn in at one end.
The movement of the smoke particles and charged air also produces a gentle breeze, and once the surplus electrons are stripped off by the plates, the now neutral air molecules are able to keep going, emerging nice and clean from the discharge end, while leaving the smoke particles collecting as a yellowish gunk on the plates.
After the bar closes, they would shut down a unit, discharge the high voltage (much like the TV picture tube flyback circuit in the old days), and then remove the collector plates. Some versions of these, you could just run the plate assembly through the dishwasher to clean off the condensed smoke. There's probably more stringent hazmat disposal protocols in place today other than just flush nicotine laden sludge dissolved in soapy water down the drain to the sewer plant.
They'd let most of them run a bit longer to get the residual smoke out of the air, before shutting down for cleaning. Depending on how much smoke was left, they might leave some of them running longer, or restart some cleaned ones to run all night and day to further clean out the air.
They made the crud build-up on everything else a lot less.
I've heard of people using the technique to "bake out" the stench of a car that has had a smoker driving it. They put one of these devices in, possibly also with activated charcoal, and then keep the interior of the car heated up to about 175 degrees F or so (or parked in the desert sun) and run the smoke collector for a few days.
I love the heat, dislike the cold!