A/C for Room Virus Removal

[Airbrush]

If you enter a building wearing your mask you may get infected right thru the mask!  All it takes is one infected person blasting out their "mist" which may linger up to HOURS.   If the building had the power to move air up and out (ANY indoor space), you CAN remove the virus from the air.  If you don't remove the virus from the room, you will get infected, good luck.

[dimreepr]

20 hours ago, Airbrush said:

you CAN remove the virus from the air. 

But you can't remove the virus from the room...

[swansont]

In addition to your lack of air flow analysis, you haven’t shown how quickly the virus, much more massive than air molecules, would get up to speed.

[Airbrush]

7 hours ago, swansont said:

In addition to your lack of air flow analysis, you haven’t shown how quickly the virus, much more massive than air molecules, would get up to speed.

Any volunteers for this analysis?

"Step right up folks!  Come into my new business (restaurant, offices, stores, markets, Disneyland, etc.) and enjoy AAR (accelerated air replacement).  My competition has poor, weak A/C that just pushes the air with virus around for an hour before it finally slinks out the ceiling.  That gives you plenty of time to get infected right thru your cloth mask.  My business, however, has fresh air ALL THE TIME for you to enjoy!  We have extra powerful fans to move the bad air out and good air in."

[J.C.MacSwell]

12 hours ago, Airbrush said:

Any volunteers for this analysis?

"Step right up folks!  Come into my new business (restaurant, offices, stores, markets, Disneyland, etc.) and enjoy AAR (accelerated air replacement).  My competition has poor, weak A/C that just pushes the air with virus around for an hour before it finally slinks out the ceiling.  That gives you plenty of time to get infected right thru your cloth mask.  My business, however, has fresh air ALL THE TIME for you to enjoy!  We have extra powerful fans to move the bad air out and good air in."

Hi Airbrush. I'm with you as far as seeing the need for better ventilation. 

I'm less certain that air should be drawn upward as a general case, as I think it could exacerbate some of the problems (such as droplets with virus getting dispersed further rather than heading to the floor), though it could be useful in some circumstances.

From an economics standpoint if you double the airflow of a system, you will require 8 times the energy to move the air, as well as double the energy to heat or cool the replacement air to the same temperature. You can change the system to partly mitigate that, but it probably requires extra equipment costs to do so.

That said, with the arrival of Covid 19 the economic considerations have changed, as you suggest.

[dimreepr]

13 hours ago, Airbrush said:

Any volunteers for this analysis?

"Step right up folks!  Come into my new business (restaurant, offices, stores, markets, Disneyland, etc.) and enjoy AAR (accelerated air replacement).  My competition has poor, weak A/C that just pushes the air with virus around for an hour before it finally slinks out the ceiling.  That gives you plenty of time to get infected right thru your cloth mask.  My business, however, has fresh air ALL THE TIME for you to enjoy!  We have extra powerful fans to move the bad air out and good air in."

How do you know you're expelling bad air and importing good air?

[swansont]

If I pull out a ping-pong ball and drop it it’s going to fall. There is some size object where the airflow will be enough to support a small sphere of some mass. But without an analysis, you don’t know if a droplet with a virus goes up, goes down, or - possibly the worst possible outcome - is merely suspended because the force of the airflow is balanced by that of gravity.

13 hours ago, Airbrush said:

Any volunteers for this analysis?

It seems apparent that you can’t do it. You should be asking questions rather than making assertions if you aren’t basing your assertions on anything.

 

13 hours ago, Airbrush said:

"Step right up folks!  Come into my new business (restaurant, offices, stores, markets, Disneyland, etc.) and enjoy AAR (accelerated air replacement).  My competition has poor, weak A/C that just pushes the air with virus around for an hour before it finally slinks out the ceiling.  That gives you plenty of time to get infected right thru your cloth mask.  My business, however, has fresh air ALL THE TIME for you to enjoy!  We have extra powerful fans to move the bad air out and good air in."

Take care you don’t leave yourself open to false advertising lawsuits.

[dimreepr]

19 minutes ago, swansont said:

If I pull out a ping-pong ball and drop it it’s going to fall. There is some size object where the airflow will be enough to support a small sphere of some mass. But without an analysis, you don’t know if a droplet with a virus goes up, goes down, or - possibly the worst possible outcome - is merely suspended because the force of the airflow is balanced by that of gravity.

Not too mention eddies in the flow.

[John Cuthber]

16 hours ago, Airbrush said:

Any volunteers for this analysis?

"Step right up folks!  Come into my new business (restaurant, offices, stores, markets, Disneyland, etc.) and enjoy AAR (accelerated air replacement).  My competition has poor, weak A/C that just pushes the air with virus around for an hour before it finally slinks out the ceiling.  That gives you plenty of time to get infected right thru your cloth mask.  My business, however, has fresh air ALL THE TIME for you to enjoy!  We have extra powerful fans to move the bad air out and good air in."

My analysis is that you just invented the pavement cafe.

 

[Airbrush]

According to Bill Maher there was a study in China that out of 7300 cases of Covid transmission only ONE was outdoor transmission.  That means that 99.999% of Covid-19 transmissions occurred INDOORS in China.

On 5/31/2020 at 8:31 AM, John Cuthber said:

My analysis is that you just invented the pavement cafe.

Yes and the indoor spaces may become ghost towns.  The economy won't recover until consumers have the confidence to enter INDOOR spaces.  "Build it and they will come" unless consumers are spooked, then they won't come.  The USA economy is mostly consumer driven.

"...In a study published by the City and Environment Interaction journal, scientists.... argue that the lack of adequate ventilation in many indoor environments -- from the workplace to the home -- increases the risk of airborne transmission of Covid-19.

https://www.sciencedaily.com/releases/2020/05/200528115750.htm

Edited June 2, 2020 by Airbrush

[dimreepr]

6 minutes ago, Airbrush said:

According to Bill Maher there was a study in China that out of 7300 cases of Covid transmission only ONE was outdoor transmission.

The first I'd imagine, no one else would want to admit the shame of their indoor activity...

[Airbrush]

On 5/31/2020 at 5:41 AM, swansont said:

If I pull out a ping-pong ball and drop it it’s going to fall. There is some size object where the airflow will be enough to support a small sphere of some mass. But without an analysis, you don’t know if a droplet with a virus goes up, goes down, or - possibly the worst possible outcome - is merely suspended because the force of the airflow is balanced by that of gravity.

You adjust the fans' speed to move the air as necessary thru experiment.  If the force of airflow is balanced with gravity, then all you need to do is slightly increase fan speed to just barely overcome gravity.

On 5/31/2020 at 5:41 AM, swansont said:

...Take care you don’t leave yourself open to false advertising lawsuits.

Right, that is why I would only say the air is replaced quicker than other businesses that have standard A/C.  The probability of getting infected indoors is reduced by accelerating air replacement.

On 5/31/2020 at 5:36 AM, dimreepr said:

How do you know you're expelling bad air and importing good air?

We will assume that outdoor air is good.  Once the bad air get outdoors the virus dilutes and dies from sunlight.

Edited June 2, 2020 by Airbrush

[CharonY]

I may have missed it somewhere but I think it is worthwhile to re-iterate that current data suggest that COVID-19 spreads via droplets rather than aerosols. I.e. most models use a parabolic ejection. There are a few suggestions that it may exist as an aerosol, but most data is not terribly compelling at this point.

As such, assuming droplet as the major source of non-contact infection, there are only limited options for ventilation to assist in that regard. Bottom up flow would likely increase the range where the droplets spread and the same goes for lateral flow. It has been discussed earlier that removing droplets before hitting someone is probably technically not feasible, which leaves downward flow. But that has to be mostly laminar otherwise we might get into turbulent mixing which would could keep particles longer afloat rather than dropping down. 

[swansont]

20 minutes ago, Airbrush said:

You adjust the fans' speed to move the air as necessary thru experiment.  If the force of airflow is balanced with gravity, then all you need to do is slightly increase fan speed to just barely overcome gravity.

The force depends on the mass and cross-section of the drop. It’s not uniform.

If it’s barely overcoming gravity, it will move very slowly at first. Not at air speed.

20 minutes ago, Airbrush said:

Right, that is why I would only say the air is replaced quicker than other businesses that have standard A/C.  The probability of getting infected indoors is reduced by accelerating air replacement.

A claim you have not demonstrated 

 

[Airbrush]

11 minutes ago, CharonY said:

I may have missed it somewhere but I think it is worthwhile to re-iterate that current data suggest that COVID-19 spreads via droplets rather than aerosols. I.e. most models use a parabolic ejection. There are a few suggestions that it may exist as an aerosol, but most data is not terribly compelling at this point.

As such, assuming droplet as the major source of non-contact infection, there are only limited options for ventilation to assist in that regard. Bottom up flow would likely increase the range where the droplets spread and the same goes for lateral flow. It has been discussed earlier that removing droplets before hitting someone is probably technically not feasible, which leaves downward flow. But that has to be mostly laminar otherwise we might get into turbulent mixing which would could keep particles longer afloat rather than dropping down. 

Then have the airflow moving downward.  Fresh air enters thru the ceiling and bad air is sucked out near the floor against the walls.  All we are trying to do is reduce the amount of time the bad air hangs around, reducing the probability of infection.

Edited June 2, 2020 by Airbrush

[MigL]

3 hours ago, Airbrush said:

According to Bill Maher there was a study in China that out of 7300 cases of Covid transmission only ONE was outdoor transmission.  That means that 99.999% of Covid-19 transmissions occurred INDOORS in China.

Assuming Bill Maher is a good source, and there is such a study, we are left with the possibility that people touch each other, and infect things, indoors a lot more than they do outdoors. I also assume that they cough evenly, whether indoors or outdoors, but most Chinese wear mask outdoors, which 'contain' most of the cough droplets and retard spread. So yes, I can 'see' that statistic being factual.
But you still haven't made the case that removing/replacing air quickly enough will prevent spread; and without either causing a 'wind tunnel' or extremely high costs which will make most businesses unworkable.

PS:  As Swansont keeps trying to point out to you, removing/replacing air is not the same as removing variable size droplets.

Edited June 2, 2020 by MigL

[CharonY]

2 minutes ago, MigL said:

Assuming Bill Maher is a good source, and there is such a study,

The study exists it is a pre-print by Qian et al and it was actually one outdoor outbreak involving two cases. The study looked at 1245 confirmed cases and 318 outbreaks overall (the main list was over 7k but some where excluded from the final list) . One of the reason is also because outdoors folks have typically less prolonged contact. One known outdoor outbreak involves a person talking to an infected person, highlighting that prolonged contact can also lead to infection outdoors. However, the majority of outbreaks (~80%) occurred at home. 

[Airbrush]

On 6/2/2020 at 10:52 AM, MigL said:

Assuming Bill Maher is a good source, and there is such a study, we are left with the possibility that people touch each other, and infect things, indoors a lot more than they do outdoors. I also assume that they cough evenly, whether indoors or outdoors, but most Chinese wear mask outdoors, which 'contain' most of the cough droplets and retard spread. So yes, I can 'see' that statistic being factual.
But you still haven't made the case that removing/replacing air quickly enough will prevent spread; and without either causing a 'wind tunnel' or extremely high costs which will make most businesses unworkable.

PS:  As Swansont keeps trying to point out to you, removing/replacing air is not the same as removing variable size droplets.

What about the fact that the longer you are in contact with a virus in the air, the higher the probability of infection?  Just reduce the time of contact.   If the airflow is downward, as CharonY suggested, even a slow, steady downward airflow will move the virus, in whatever form, down near the floor.  It drops below breathable range in seconds.  That is a slow, steady, downward airflow.  That will actually push skirts made of tissue paper downward. 

That would be a big improvement over the virus lingering in the air for hours.  There may be a virus residue on the floor, and near the wall exhaust vents, but that can be sprayed with sanitizer after people leave the building.  There may even be a way to retro-fit indoor spaces with additional fans to push and pull the air.  The business owner may rightfully boast about this to attract employees and customers.  Wouldn't you like to work or shop where the air is fresher and cleaner?

Edited June 5, 2020 by Airbrush

[Buckeye]

* Indoor transmission of sars-cov-2 can take place by large respiratory droplets (larger than about 100 microns and fall to ground before drying), small respiratory droplets (less than 5microns and can become aerosolized), and fomites(transmission from contaminated surfaces.

Transmission of aerosols in indoor environments  was described in recent research paper (see reference refered to below).The research found significant reduction by using sufficient and effective ventilation, particle filtration of air (hepa filters in the hvac system), air disinfection by uvc lights in air ducts, avoiding air recirculation and avoiding overcrowding of indoor spaces. In addition to these engineering Controls, the traditional personal controls (social distancing, hand hygiene, ) are used.

*These recent research findings are in"How can airborne transmission of Covid-19 indoors be minimized" Environmental int 2020 sep. 142: PI's are Lidia Morawska, Julian W Tang,and Maosheng Yao. Detailed advise on specifics of engineering Controls of indoor built environment can be found at the web site of American Society of Heating, Refrigeration, and Air-conditioning Engineers(ASHRAE). This research is a good example of interdisciplinary collaboration between mechanical engineers and microbiolgists, and could save lives.

Edited September 15, 2020 by Buckeye
Title clarification

[CharonY]

!

Moderator Note

Merged similar topics.

 

[Airbrush]

Why did my Costco installed giant ceiling fans above the checkout stands?  To suck the air upwards.

Is there a way to retro-fit a room to have 12" diameter ducts transport fresh air (from outdoors) to the ceiling of a room to introduce air to the room, and have 12" ducts snake along walls to suck stale air out through vents near the floor, along the walls?  Can this be enough to speed up air replacement?  All this requires is air ducts and some powerful fans.

Edited November 12, 2020 by Airbrush

[swansont]

Yes, it would speed up air replacement. The question is by how much, and that requires analysis. It could be that the Costco situation is for show, or it could have a measurable effect. Can’t tell

[dimreepr]

32 minutes ago, Airbrush said:

Is there a way to retro-fit a room to have 12" diameter ducts transport fresh air (from outdoors) to the ceiling of a room to introduce air to the room, and have 12" ducts snake along walls to suck stale air out through vents near the floor, along the walls?  Can this be enough to speed up air replacement?  All this requires is air ducts and some powerful fans.

Why bother?

It's a "catch 22":

Me, happy happy happy... Dead...

You, worried worried worried... Dead...

 

[J.C.MacSwell]

9 minutes ago, dimreepr said:

Why bother?

It's a "catch 22":

Me, happy happy happy... Dead...

You, worried worried worried... Dead...

 

Why wear a seatbelt when you can still be killed while wearing one?

Risk reduction.

[dimreepr]

Just now, J.C.MacSwell said:

Why wear a seatbelt when you can still be killed while wearing one?

Risk reduction.

Does that mean you're less dead?

Your missing the point; you can be happy to wear a seatbelt...😉