Publish Time: 2022-08-22 Origin: Site
The Civil Aviation Administration of China has published an article saying that the vertical air supply system of the aircraft, combined with the HEPA filter element, can filter out 99% of the virus.
Where does the fresh air in an airplane cabin come from? Most of the time, the air we breathe in the cabin comes from mixed air, so why not just use fresh air? Because the air outside the cabin is about minus 30 to 40 degrees when the plane is cruising, there is not enough oxygen directly blown in, and the temperature is enough to freeze people to death.
The air conditioner on the aircraft uses the high-pressure air drawn from the engine as the power source, and uses the outside low-temperature air as the cooling medium, which is mixed proportionally in a place called the mix manifold to form the available air-conditioning air. The cooled air-conditioning air needs to be mixed with the original cabin air after passing through the high-efficiency filter before it can be blown out.
HEPA filter
This HEPA uses ultra-fine glass fiber paper as the filter material, offset paper, aluminum film and other materials as the dividing plate, which is glued with the wooden frame aluminum alloy. HEPA is made of special silicone rubber, odorless, the surface will not harden, and there will be no cracks for a long time, chemical properties are stable, corrosion resistance, can absorb the stress generated by thermal expansion and contraction without cracking, moderate hardness, elasticity recovered well. Each unit has been tested by the sodium flame method and has the characteristics of high filtration efficiency, low resistance and large dust holding capacity.
Boeing pointed out in the maintenance manual that HEPA can effectively capture 0.003-10 micron particles, and the filtration efficiency of 0.3 micron pollutant particles can reach 99.97%. Airbus also released a technical document on the Wuhan epidemic on January 23, 2020, arguing that the aircraft's HEPA can filter out 99.99% of virus and bacterial particles.
Can this filter alone keep the infection rate on the plane so low? And its unique air-conditioning layout. It is blown out by the air conditioning system from the air vents above the seats and finally drawn back through the grille on the side close to the floor. This design feature makes the direction of air flow in the cabin basically vertical, and the air flow along the longitudinal direction of the fuselage is very small, which ensures the cleanliness and freshness of the air in the cabin to the greatest extent. Spread in the cabin. Air is replaced in the aircraft cabin every 2 to 3 minutes, 20-30 times per hour. So the risk is reduced to a very low risk.
Since the unique layout is conducive to reducing infection, is it necessary to change the car to an airplane?
The answer is not necessary.
First of all, in terms of structural principle, it is difficult for the aircraft to have independent air outlets in each row, and the cost is extremely high, which is not conducive to the structural layout of the cabin.
Secondly, this arrangement is deliberate, because the car can open the window for ventilation when the air in the car is turbid, but the plane cannot, so it must be ensured that the fresh air is flooded.
Third, the epidemic is only temporary. The traditional car air outlet layout has been tested for many years, and there are many considerations for in-car replacement and even safety. Although it is not difficult to change to overhead air supply, the re-layout needs to modify the roof of the body, arrange pipes, and punch holes, etc., which will affect the rigidity of the roof and affect the whole body. Moreover, with the current vehicle filter technology, the filtering effect can be completely achieved.