Heat exchanger coils
Super Radiator Coils
Chaska, MN

A 25-foot-high wall of heat exchanger coils manufactured by Super Radiator Coils will replace the coils in the Icing Research Tunnel (IRT) at NASA’s John H. Glenn Research Center in Cleveland, OH. When installed and commissioned, the new coils will enable the IRT to lower the air temperature faster and more efficiently to -40 °F, which will be 15 degrees colder than its current capacity.

The IRT has been in continuous operation since 1944, and is one the world’s largest and busiest research facilities that simulates atmospheric icing conditions. Its closed-loop tunnel uses a 5,200-horsepower motor and 14-foot prop-fan to recirculate air at speeds of 50 to 300 knots per hour (31 to 186 miles per hour). Downstream from the bank of coils are misters that inject water into the air stream, which freezes upon contact with the test specimen.

Aeronautic design engineers, aircraft manufacturers, and airlines from around the world use the facility to test wing design and other aircraft components under icing weather conditions. The new coils took about four months to build. The company previously designed and manufactured coils for 14 other wind tunnels, including NASA’s Ames Research Center in Moffett Field, CA.

Designing the high-efficiency, cascade-style heat exchangers to meet NASA’s specifications was a collaborative effort between Super Radiator and Jacobs Technology (Tullahoma, TN), which specializes in wind tunnel design.

The innovative design tilts the heat exchanger coils forward in a slant configuration, which effectively doubles the exposed face area of the coils. The result is a dramatic increase in the heat transfer capabilities of the coils, while reducing the air velocity and preventing ice shedding from the coils.

The $1.2-million project includes six large coils or modules of heat exchanger coils that will be stacked on top of each other in the IRT to form a wall that air must pass through before entering the test chamber in the wind tunnel. Each module is 4.4 feet high, nearly 9 feet wide, and 50 feet long.

More than 30 miles of 5/8"-diameter copper tubing was used to form the coils, which have enough heat-dissipating aluminum fins around them to cover a football field. The six banks of coils will weigh 110 tons when a refrigerant is put inside the tubes.

Besides the massive wall of heat exchanger coils, the IRT’s remodeling project involves replacing all of the refrigeration equipment, including compressors, piping, instrumentation, and controls. The new system will use advanced, low-temperature refrigerants.

The overall height, weight, and length of the coils, along with the core weight of the multi-angled framework that will hold the coils in each module, were all manufactured to a non-standard design. The next challenge will be to carefully place all six coil modules on top of each other to perform as one gigantic heat exchanger coil, taking into account variances in thermal expansion and contraction.

The six modules were assembled and tested by Super Radiator at its facilities in Chaska. They will be transported to the IRT, then lowered through the roof into the wind tunnel. After final assembly, installation, and additional testing, the IRT is expected to become operational by late fall. The new coils will be the third generation of heat exchanger coils to be used in the IRT. The current coils were installed about ten years ago.

Tests performed in the IRT include fundamental studies of icing physics, icing prediction validation, and ice protection system development and certification. Applications include developing and certifying next-generation ice protection systems for both military and commercial aircraft.

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NASA Tech Briefs Magazine

This article first appeared in the August, 2011 issue of NASA Tech Briefs Magazine.

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