Thermal Energy Storage - Airlines Reduce Operating Costs with Ice Balls

Repeat Installations Keep Design Costs Down and Reflect Operational Satisfaction

You are sitting in a wide-body aircraft on a hot, humid afternoon at Miami International Airport. You are shoulder to shoulder with a couple hundred people and the doors of the plane are open as the ground crew loads up the soft drinks and peanuts for the flight. Even though the plane is on time, you know it may be a while. Fortunately, that little nozzle above your head is blasting out cold air. How do they do that? How can they afford to keep so many people cool in a confined space with the doors open? The answers can be found in PCA (preconditioned air) and TES (thermal energy storage).

In the past, an airplane's auxiliary power unit (APU) was called upon to supply cooling. The APU is a small jet engine designed to provide cooling, electrical power and, in some cases, power to start the main engines. These engines consume between 35 and 120 gallons of jet fuel per hour. In addition to high fuel costs, the APU is subject to costly FAA approved maintenance based on hours of operation.

Thermal Energy Storage For International Airport in Southeast

The economic and practical necessities of shifting air conditioning loads away from costly APU engines led to development of the PCA system. The economics of electrical power to run PCA chillers led to the addition of thermal energy storage.

As compared to typical air conditioning systems, these installations are designed for the most extreme demands. The most obvious extremes are those associated with high, short-term loads imposed on the system while the aircraft is parked followed by no-load conditions when the plane departs. In addition to the "peaky" intermittent demands for cooling, PCA systems normally use 100% outside air for cooling and ventilation. Of course, this means high temperature air (and often very humid air) must be cooled without the benefit of recirculation - remember, the doors are open.

PCA ducting under jetway

To accomplish the task of managing such extremes in an economical manner, water-cooled industrial grade chillers are combined with thermal energy storage in a low temperature glycol loop. The system supplies aircraft with a large volume of relatively high-pressure air (22 inches of water) at the low temperature of approximately 30F. In order to meet such unusual conditions, cold fluid from the glycol based system is delivered at about 20F. Thermal storage not only flattens the peak loads inherent with such an application but also allows the use of lower cost off-peak electricity to charge the system at night.

Cryogel Ice Ball Thermal Storage Tank

Exact details of the low temperature process are proprietary and the key system components and Cryogel Ice BallTM thermal storage media are protected by patents.
Since 1995, ten PCA systems using Cryogel Ice Balls have been installed for major airlines at the international airports in Atlanta, Miami, San Francisco, Los Angeles, Chicago, Phoenix and Dallas/Ft. Worth.   The simple fact that the same airlines continue to install system after system is the strongest single indicator of the economical operation and reliability of the combined PCA/TES concept.

By: Victor J. Ott, P.E.
President of Cryogel, San Diego, CA

Cryogel supplied more than 18 Million Ice Balls to domestic and international projects over the past 10 years.
For more information call (858) 457-1837 or send email to:  
Copyright Cryogel, 2001  All rights reserved.

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