MEBAA Convention News

Even VIPs feel washed out without humidity

 - December 6, 2010, 2:28 AM

It should go without saying that private jet passengers generally enjoy more space, more comfortable seats and more advanced cabin systems than their airline counterparts. But the benefits of all these luxuries can be badly undermined by inadequate humidity levels in the cabin that can make the VIP traveler as weary as an economy-class pauper at the end of a long flight.

CTT Systems (Booth No. E154) has an answer to this conundrum in the shape of its Cair system, which can ensure that comfortable levels of humidity are maintained throughout a flight. It works in tandem with the Swedish company's Zonal Drying technology to ensure that excessive condensation does not gather in places where it can damage the fabric of the aircraft, while also causing excess weight and wasteful fuel burn.

Unlike economy-class cabins where large numbers of passengers generate plenty of natural humidity, VIP and first-class airliner cabins (as well as cockpits) carry only small numbers of people, so the humidity at altitude will drop to levels that can have a debilitating effect on humans since dehydration worsens the effects of travel fatigue and jet lag. In a building on the ground the relative humidity would normally be between 50 and 60 percent, but in an aircraft at 33,000 feet it would drop to just 5 to 15 percent because the outside air is extremely dry at that altitude and about half of the air inside is drawn in through the engines.

Each passenger generates about 3.5 ounces of water per flight hour. So, 10 passengers making a 10-hour flight on a business jet will produce 350 ounces of water, while 400 passengers making the same journey on an airliner will produce just over 109 U.S. gallons.

So far, CTT has installed the Cair system in about 40 private aircraft-almost half of which have been Boeing Business Jets. The equipment is also approved for the Airbus Corporate Jetliner family (starting with the A318 Elite), as well as VIP versions of the A330 and A340, and for the Boeing 747 and 777. The company is now pursuing first applications for the new 747-8, as well as for VIP versions of the A380.

How It Works

The Cair system uses one or more humidifiers connected to a water supply. The humidifiers include a pad of glass fiber with specially designed, moistened air channels. When dry air passes through the moist surface of the pad, the water evaporates and the air is humidified as it cools. The size of the pad is determined by the volume of airflow to be humidified, and by regulating the water supply and the temperature of the air as it reaches the pad, the system can run automatically.

Minerals and other water contaminants are trapped in the pad. According to CTT, the risk of spreading bacteria through the system is minimal because the water evaporates as it transfers into the air and so cannot carry bacteria.

For aircraft cabins, the humidifier is installed in air supply ducts leading to the area to be humidified. CTT can also provide separate humidifiers to serve the cockpit and crew rest areas.

The Zonal Drying system, consisting of a fan, a heater and a rotor, takes air from the aircraft atmosphere, removes the moisture from it and then blows it into the gap between the cabin and the aircraft skin. This creates a barrier of dry air, which in turn dries out the aircraft's insulation blankets that otherwise would be saturated with condensation.

At the same time, the relative humidity of the air coming into contact with cold surfaces is lowered, reducing condensation. Depending on the aircraft type, the Zonal Drying unit is installed either in the crown area at the top of the fuselage or beneath the cabin floor.