21 September 1999

Putting a refrigerator in the tank?

by Kate Melville

The airline industry are looking at using cooled jet fuel, to make aircraft safer to fly and more environmentally friendly while increasing their range

It's a simple enough idea:

1 - Cooled fuel has increased energy density, enabling an aircraft to fly further on an equal volume of fuel

2 - Cooler fuel reduces the formation of fuel vapor from evaporation and it's fuel vapor within an aircraft's tanks that can poses a risk for explosion and fire

3 - Vapor venting from fuel tanks, creates smog-forming ozone.

The concept was tested on Sept. 15, at Meacham International Airport, Fort Worth Texas. Involved in the tests were the researchers' from the University of North Dakota, Energy & Environmental Research Center (EERC) and the Odegard School of Aerospace Science as part of phase one of a project with Fuel Dynamics Inc. of Arlington, Texas. The aim was to demonstrate the potential of Fuel Dynamics, Polarjet(TM) refueling technology.

According to Ted Aulich, for EERC, "during warm weather, the sun's rays and certain onboard aircraft systems heat jet fuel to temperatures of 90 degrees or more, speeding evaporation and lowering the fuel's energy density. Fuel vapor not only contributes to smog-forming ozone, but also builds up in the plane's internal fuel tanks, creating the potential for an explosion when the vapor is exposed to a spark or fire".

During the test in Fort Worth, one wing tank of a private jet was loaded with normal-temperature fuel and the other tank loaded with fuel cooled by the Polarjet technology, enabling scientists to measure the differences in fuel vapor within the tanks.

Terry Koethe of Fuel Dynamics who originally devised the idea of using chilled aircraft fuel many years ago developed the idea for Polarjet. "The process that started out as a means to achieve greater flight endurance has ultimately evolved into what I expect to be the world's only safe and practical jet fuel," Koethe said.

While still somewhat contentious perhaps the best-known example of a fuel vapor explosion occurred when TWA Flight 800 exploded and crashed into the Atlantic Ocean off the coast of Long Island, killing all 230 people aboard. Investigators say the source of the explosion was fuel vapors in the plane's center fuel tank, although they don't know what sparked the explosion.

Both the aircraft industry and the Federal Aviation Administration (FAA) are pursuing a noncombustible fuel tank but the Polarjet approach is claimed to not require any changes to the aircraft themselves or the fuel they use.

and is just as fast as current refueling technologies," he explains. "We can provide a new degree of safety in almost any type of accident, and we can save the airlines money because their planes will go further."

The Polarjet(TM) technology uses a high-tech refrigeration system to lower the temperature of large quantities of jet fuelto as low as 25 degrees Fahrenheit. In addition to cooling the fuel, the Polarjet refueling systems also inject nitrogen gas into the plane's fuel tanks while the chilled fuel is being loaded. The idea behind this is that the nitrogen initially replaces oxygen in the tanks, further eliminating the possibility of combustion. The nitrogen is eventually vented out of the tanks and replaced by air. Fule Dynomics claim that even with oxygen present, evaporation from the cooled fuel is so limited that the concentration of hydrocarbons in the fuel vapor is greatly reduced and with it the chances of vapor being ignited by a spark are almost zero.

So now while we fly we shall only have to worry about:

Computer malfunctions

Suspect wiring

The suicidal tendencies of pilots, aircrew and fellow passengers

Human error

Overloaded aircraft control systems


Food poisoning

Lost baggage