Aeroplane airconditioning

[Burrah Boy]

Hi everyone. Does anyone know of a good read on how airconditioning works in aeroplanes. I have googled a few links, but nothing of substance. I did find a link on book, but it was a pilots handbook on a boeing 737.
It is just a matter of curiosity that I want to read up on.
Thanks

[Sridhar1312]

The aeroplane is air conditioned by taking outside air and heating it with heat exchage with exhaust indirectly and given to the cabin.
As the air at higher altitude is at sub zero temperature and it is heated to comfortable temperature.Thus the RH in plane is always low and hence it is always suggested to take water while traveling in Aeroplane

[sinewave]

Thus the RH in plane is always low and hence it is always suggested to take water while traveling in Aeroplane

I tend to consume Alcohol!


That's where I'm going wrong is it!

[Brian_UK]

If you are talking about small aircraft, Cessna etc, then they tended to use electrically driven auto-type compressors with ducted evaporators.

Single engine aircraft have direct drive compressors so take long hoses with you

[taz24]

Hi everyone. Does anyone know of a good read on how airconditioning works in aeroplanes. I have googled a few links, but nothing of substance. I did find a link on book, but it was a pilots handbook on a boeing 737.
It is just a matter of curiosity that I want to read up on.
Thanks

Just open the window!!

taz.

[Burrah Boy]

Thanks for ALL the informative answers, especially from Sridhar123. I know that on the ground, some airports have ducts that they connect to the plane where they take cooling from underground, where plastic balls that are part filled with water (due to expansion) are frozen overnight (due to cheaper energy rates), by a chiller, and that cooling then supplied to the plane!

[Quality]

I did some work over 10 years ago on the Raf VC10 they had a DX a/c system for use on the ground using R114 the compressor was a little bit like a turbo driving a small centrif operating by whats called ram air from the engine / jet.

When in flight its rarely needed dut to the low temps at high altitude although they did use spill air from the exterior to control humidity.

For what its worth http://www.flightglobal.com/pdfarchi...0-%201322.html

hope this helps

[back2space]

I did some work over 10 years ago on the Raf VC10 they had a DX a/c system for use on the ground using R114 the compressor was a little bit like a turbo driving a small centrif operating by whats called ram air from the engine / jet.

When in flight its rarely needed dut to the low temps at high altitude although they did use spill air from the exterior to control humidity.

For what its worth http://www.flightglobal.com/pdfarchi...0-%201322.html

hope this helps

mostly the air conditioning on the ground this is done with portable truck units, those big yellow ducts..the packs do supply , but with the apu running it uses spending 500 lbs of fuel per hour.
so depending on the carrier, some prohibit / restrict apu ops till the last 30 minutes of ground time, some don't care at all. 20 ~ 25 degree difference between oat and cabin temp , when not conditioned, isn't rare. very nice in Jan, not so in Aug..

[back2space]

It is not like the refrigerant cycle A/C that you might have at home or in the car. It is called an air cycle air conditioner, or Air Cycle Machine (ACM). It uses the principle of thermal dynamics to cool the air and is the pressurization system of the aircraft.

Very hot (300°F) high pressure bleed air is brought in and passed through a primary heat exchanger to cool the air.
The cool air coming from the primary heat exchanger is denser and lower in pressure than the bleed air, so it is then sent to the compressor to boost the pressure again.
The increase in pressure causes the air to heat up again (450ºF+) before sending it through the secondary heat exchanger to cool it off again.
The cooler air is then sent through an expansion valve and is used to drive a turbine which is coupled to and drives the compressor. (No power needed)



The expansion of the air and the work being done by the turbine causes the air temp to reach sub-freezing temps.
Warm air from the bleed is used to keep ice from forming on the turbine blades.
The air is then sent through a water separator to prevent moisture build up in the cabin. This is why the humidity is so low.
Additional hot bleed air is then added to the air flow to regulate the cabin temp.

Have a read at these links ive researched it a lot of times as was always interested:

http://en.wikipedia.org/wiki/Air_cycle_machine

http://www.boeing.com/commercial/cabinair/ecs.pdf

http://www.advisorybodies.doh.gov.uk...tox0621add.pdf

http://www.airliners.net/aviation-fo...ad.main/221730

They do recycle some of it through HEPA filters with complete air exchange with outside air about every 5-10 mins.
They must keep a continuous in-flow and out-flow of air to prevent the build up of moisture, co², and to help with odor control from stinky passengers.
If they didn't, moisture in the air coming from the passengers exhaling, would condense and build up on the cold inner skin of the fuselage behind the trim panels. The insulation between the panels and skin would collect the water and retain it. This would cause corrosion in the aluminum, and could get into the wiring connectors and cause a fault.
The stale air smell is more likely caused by a dirty coaliser bag or dirty "sock" in the ACM water separator. This is more likely to happen when the aircraft fly's short hops or in and out of pollution filled cities.
It can also occur when flying in damp weather when the water separator becomes saturated or the drain is plugged up. Much the same as when you sometimes get that dirty sock smell from the car A/C on humid or wet days.

Its such an efficient technology they are starting to develop cooling and heating systems - scroll down the next link to read what they can be used for... an interesting read!

http://www.frperc.bris.ac.uk/res/res5.htm

Im sat at work and not busy and you have got me back onto it researching it!!

The A380 A/C system there is a video here, dont understand the language but shows you some testing of the A380 system:

http://www.youtube.com/watch?v=Qu2od3Q_g04

They produce a total of 752 KBTU/hour of cooling, or 62 tons of cooling! THeres was a programme on discovery channel that showed the fast size of the system it was huge!

Hope this helps let me know if you find anything interesting.

Regards
Richard.

[Burrah Boy]

Back2space, wow, that is even more than I expected and is exactly what I was looking for. Thanks for the great effort.
You are THE MAN!

[back2space]

Back2space, wow, that is even more than I expected and is exactly what I was looking for. Thanks for the great effort.
You are THE MAN!

Enjoy the read!

U could click the scales next to my name to make it even better hehe!

[back2space]

Old thread but may be useful for the poster. This train manufacturer are using air cycle machines in their train air con systems.

http://www.liebherr.com/catXmedia/ts...d649624288.pdf

Wonder how long before air cycle machines will be used in buildings.

[swaminathan van]

hi there, i remember some one telling me a long time ago that they use a bleed from the compressor and pass it through an expansion nozzle and a heat exchanger from the cabin air rejects heat to outside.this way there is no need for additional power for the climate control.hope this helps.nathan

[back2space]

This is a very good link that explains it all...

http://www.k-makris.gr/AircraftCompo...lPack/pack.htm

[D.D.KORANNE]

Very interesting links & information on this thread .