Air condiioning with Oxygen

Hello tcchandran,

Is there any solution for this to add oxygen with minimum loss of cold air?

Not in a practical way.

You do need to constantly add some external air, or your inside folks are not going to remain alive for very long.

Depending on the volume indoors, and the number of persons still alive and breathing, you may use chemical "scrubber" agents to remove the Carbon Dioxide.

There is a very fine Website which has plenty of detailed information re CO₂ scrubbers, just click on the link below:

http://process-equipment.globalspec.com/Industrial-Directory/co2_scrubber

If you need further information, please reply in this Topic Thread right here .....

Yes there is a solution for this by Panasonic air conditioners, but not sure with minimum loss of cold air. And please see this in Panasonic website for more informations.

Good luck and health with Oxygen.

all buildings need ventilation; fresh air. An energy-saving approach would be to have a heat exchanger to extract heat from the out going air and transfer it to the incoming air. Since you have an air conditioner you could duct your extract vent to the air conditioner and recover the heat that way. Obviously your inlet vent would need to pick up heat from the air conditioner heat sink. If you are cooling (and being Asia that's probably the case) the reverse will be true, your incoming air goes over the heat source and your outgoing air - which is cooler than outside air - goes over the heat sink before being vented. If you want to do both a 4-way reversing valve in the heat pump, I think takes care of that. Insulation to avoid heat bridges will be pretty important. There probably is a solution available off the shelf.

This a mature technology, counter current in wall heat exchangers.

http://www.google.ca/search?hl=en&q=counter+current+in+wall+heat+exchangers&btnG=Google+Search&meta=

"There is, therefore, a stage when the indoor oxygen content of the air gets depleted and replaced by carbon dioxide caused by expiration of the inmates of the room being condiioned."

There is...little likelihood of the occupants of a normal dwelling, room or house becoming oxygen starved and asphyxiated. Usually there is too much infiltration of outside air due to wind, cracks in walls, floors, and ceilings as well as doors beinge opened and closed.

Usually the problem is to minimize such extraneous air changes to minimize the cooling costs.

The counter current heat exchangers allow inside air to exit in direct contact with outside air with a high grade heat conductor separating them. The better ones use a wicking medium so the condensation as the inside air cools is wicked through to the incoming cold and dry air to reduce the need for internal humidity control..

These allow ample oxygen exchange and are about 95% efficient at their design volume of flow(which is low as it just needs to replace the oxygen the occupants consume which is the oxygen contained in 6 liters of air every minute per average person(varies with weight and resting state but is about 1.25 liters/minute of O2).

a 1500 square foot house with 10 foot ceilings holds 15,000 scf of air at 21% O2

= 3150 cubic feet of O2 =~90,000 divide by 1.25 = 72,000 minutes or 50 days to zero and 25 days to about 10%. Depending on physiological factors and resting state you can eke out an existence to less than 5% O2 in the air. although I did not find a precise level at which you expire from low oxygen in the air.

In any event it does not take very much new air per person to keep people happy.

The "fresh air" myth is probably a too warm house that manifests as a desire to open a window. Landlords should place a window switch in series with the thermostat so if the tenants open the windows the heat shuts off. If they complain he comes over and tell them it's cold because you opened the bloody windows ya stupid git

Stirling Sam is correct regarding this the standard AC unit / High wall split has no provision for fresh air make up. Most ducted systems do. However I would doubt if any homes or Public buildings (which do have make up air) are airtight enough to cause a problem. Standard High wall splits have been used for a long time and I have never heard of a case regarding oxygen deprivation. You are making mountains out of mole hills

wouldn't it be possible to have enough greenery in the room to offset the oxygen consumption? Cover every square inch of the walls and ceiling with moss, for example, which takes moisture from the air, fixes carbon dioxide, and releases oxygen. It doesn't like direct sunlight, so moss would probably do well with standard indoor lighting (maybe filtered to provide the specific wavelengths moss needs most). How many square feet of moss would be necessary per human?

I remember shortly after the mercury program at NASA, several astronauts were involved with experiments in creating deep water habitats, living in a large diving bell hundreds of feet deep, slowly lowering the bell as people became accustomed to the pressure. The idea was that it would allow humans in scuba gear to do deep water exploration for weeks or months at a time rather than making quick dives in bathyspheres. It was also intended to study people in isolation from the outside world enjoying the company of a very few fellow scientists as might be the case in a moon base or a long journey, such as to mars.

Whatever became of that research?

The human body finds oxygen to be toxic at about 30 PSIA, so there has been a body of research done by the US navy on heliox mixtures

http://www.google.ca/search?hl=en&q=%22us+navy%22+%2Bheliox&btnG=Google+Search&meta=

drill there

This work is needed for longterm stays belowthe 1500 mm partial pressure of O2, about 250 feet. You can use lesser levels of Oxygen to postpone thism but Nitrogen produces a narcosis beneath about 400 feet so you have to go to exotic mixtures around that level , more or less.

Some of those references get into other exotic mistures. Some use rebreathers to save $$ and maintain secrecy.

Navy wants it for salvage and if your pressuriz a 1000 foot dive sub to 1000 feet in advanmve, it can now go to 2000 fet before collapse. Of course, it may explode on surface...

This oxygen depletion would be a problem in a perfectly insulated home in which all the inhabitants remained shut in the house for a lifetime. However, children tend to run outdoors to play, teh adults must exit the house for employment, and some even do a little gardening. As a result, the atmosphere content of the house does become exchanged with the atmosphere outside the house on a regular basis. In addition, it woud require a huge expense to seal the house completely. The air will naturally filter in, people will open doors and windows. We have been using Air conditioning in the USA since World War II and I have yet to hear of anyone being oxygen deprived because of air conditioning. Yes, there are many otehr reasons for carbon monoxide and carbon dioxide poisoning, but most of these center around open flames inside the home and nto air conditioning. A gas cook stove or open flame space heater is by far more dangerous than is an air conditioner and is also very common in China and many other countries.

Bathrooms usually have ventilation fans to minimize odors. This is normally enough air flow to satisfy fresh air requirements, as the air enters the building through doors, windows, and sometimes ventilators.

The air-to-air heat exchangers are an excellent idea in the long run, but are still fairly expensive and may have a low ROI.

Lived in the PHILIPPINES. Can't believe the buildings are that tight in your location. They aren't that tight in the colder climates. Have many deaths by CO2 in this area?

James

very few places are so tight that you can suffocate and not know it. Gradualy loss of oxygen and accumulation of CO2 has bad side effects. CO will pooison you, but CO2 will not, it makes you pant

In my message, I did not report of anyone suffocating or dying in an A/C room. All I said was, that, in a closed room where there is no provision by design to bring in fresh air, there is a tendency for co2 level to build up which is not as healthy as a room that has a fairly good supply of fresh air.So, I was wondering if there was technology available out there( may be novel heat exchangers) to get in a supply of fresh air with minimum loss of cold air. Leaks in the room will surely let in O2 but it will not be as efficient as a room to supply fresh air by design. In older window type air conditioners,there is a provision to mix fresh air through a vent. Most of the modern split systems do not have this provision.

Hi tcchandran,

There are many solutions for your problem e.g. first you must to filter CO₂ in exhausted air from your room then mix O₂ (or fresh air from out door) to this filtered air.

But here you have to lost energy for ventilation fan and O₂ pump(or fan),.... this is too complex and not too economic.

So there are popular solutions now:

In individual house you can use ventilation fan for each room where need to be ventilated; or you can install ventilation pipe system with one or more ventilated fan.

In building center you can use ventilation system.

And answer for your question that "most of the modern split AC manufacturer do not have this provision" , because of the trade competition and if there is anyone it is not really effective.

One form of Air Conditioning is to compress outside air to about 300 psig, let it cool and release it to the inside of your house. The air has no additional CO₂ other than natural in the atmosphere and is fully exchanged as the outside air is pumped inside. This form of air conditioning does work but can also be very energy inefficient. It simply uses Boyle's Law.

tcchandran - You are right in that the suffocating issue is too extreme for this problem. The need for "fresh air" is not just to provide O2 and remove the poisonous CO2 but is also to remove odours and other pollutants. The amount of fresh air will dictate the performance of the occupants.

About 10 years ago in the UK the term "Sick Building Syndrome" was high profile and was a result of the poor air quality provided (primarily) in offices. This has improved in recent years as the amount and quality of fresh air has improved.

As for equipment there are a lot of air-to-air heat exchangers out in the world to suit all sizes and budgets, these being from a standard range or purpose made to suit the airflows and temperatures involved - just google it and you should get a good selection from your locality.

Good Luck

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