Why is the air inside the airplane so dry?

Question

Whenever I travel this bothers me. Why is it so dry inside the aircraft? Do you have similar problems?

Answer 1

Humidity on an aircraft is low for 2 reasons.
1. Conditioned air for temperature and pressure control is bleed air from the engines ( on jets). All it is is a tube that comes off the compressor before the air is mixed with fuel and runs to the ACM (Air Cycle Machine). For all intents and purposes the ACM is an airconditioner. Bleed air is very, very, very hot because it is compressed, which makes the air very dry. It runs through the ACM by way of air to air heat exchangers, an expansion turbine, valves and other components giving you cold air. That mixed with the hot to varying amounts gives you the temperature in the cabin. There is no humidifier built into this.
2. Humid air, being that the air contains water, can eventually lead to corrosion. Which is very bad for airplanes. Pure aluminum is corrosion resistant, but aircraft skin and structure are clad aluminum, it is stronger. Meaning aluminum alloy in the middle that can corrode, coated by pure aluminum.
I believe part of Boeing's intent with using a lot of carbon fiber on the structure of the 787 is to allow higher humidity and pressure in the cabin for comfort.
And like one of the answers said, you can get " snow " to come out of the vents if you turn it down cold enough. Its kind of cool.

Answer 2

One cause of dry air in an airplane cabin is that the air at altitude is colder and at a lower pressure than air at sea level, so it can not hold as much moisture as the air we're used to on the ground. The air inside the cabin comes from the engine compressors at several hundred degreed F and typically goes through a series of heat exchangers and a turbine to cool it to a comfortable temperature. Coalescer systems remove a good deal of the moisture at lower altitudes.
The air management system combines this fresh air with recirculated air in an attempt to maximize passenger comfort. Humidification systems would be feasible, but since the cabin isn't maintained at sea level pressure, there would be a lot of condensation by the time the plane landed.

Answer 3

The humidity point of the air exterior is amazingly low at extreme altitudes, and cabin air comes from the exterior. maximum airplanes recirculate area of the air by filters, as a manner to strengthen the humidity slightly and shrink the quantity of power taken from the engines, however the air could be very dry. some plane, such by way of fact the Boeing 747 and another airliners, supply humidifiers as a shopper decision, yet they do no longer seem to be broadly used (basically a pair of million in 10 proprietors of Boeing 747s has them put in). somewhat extreme humidity can sell corrosion, yet given how extreme humidity can upward push on the floor, it is not sparkling that humidifying the air slightly aloft will develop up corrosion severely. it extremely is an extra and pointless price, however, so operators is probably no longer prepared on it.

Answer 4

The airplane doesn't always have dry air inside. On takeoff and landing, the air is like the air outside. At cruise altitude, The airplane is above nearly all weather systems and is in very dry air. This dry air supplies the interior so the interior air is likewise dry.

Answer 5

The air comes from the engines. The air is compressed, which heats it up. Then it is sent through heat exchangers, and then decompressed. When it decompresses the air cools down, lower than when it started. When that happens the moisture condenses out of the air. The water mist is separated out of the air flow and is dumped over board, leaving dry air. Its called air cycle air conditioning (compared to vapor cycle, like in your car).

Its possible to get snow to form and come out the vents if some part fails, cant remember what though...

Answer 6

The air on an airplane is recycled and conditioned so it loses its humidity

Answer 7

Dry air is lighter than moist air, therefore less weight in the plane