Composites Today

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GTL Announces validation of LH2 composites Dewar-Tanks for aviation applications

Gloyer-Taylor Laboratories, Inc. (GTL), US, an aerospace engineering research and development company has announced that its innovative hydrogen storage technology, small subscale composites vacuum jacketed dewar-tank with liquid hydrogen (LH2) has been successfully validated.

According to the announcement the GTL composites LH2 dewar-tank test results surpassed expectations. When fully isolated, GTL’s dewar-tank held hard vacuum at 2.8.e-6 torr for ~50 minutes with LH2, which was > 100x better than the requirement. This allowed the GTL dewar-tank to hold LH2 for over 21 hours, at -430 degrees Fahrenheit, while remaining leak tight with minimal hydrogen permeation. During this test, the subscale dewar-tank experienced only 2.8 watts of heat load. Based on this, GTL expects that the flight tanks will see only 1% LH2 boiloff per day.

Results showed the composites dewar-tank’s ability for rapid chill-down, paving the way for aircraft to be refueled in minutes, versus waiting hours for a metal tank and transfer lines to cool. The inner composite tank went from ambient room temperature to 20K (degrees Kelvin) and holding liquid hydrogen in less than 20 seconds and the GTL composite tubes achieved full LH2 flow in less than 1 second. The tests also show that no-vent fills of the composite dewar-tanks are achievable, which greatly improves refueling safety.

“With these successful validation tests, we have achieved a critical milestone in aircraft decarbonization. GTL is now proceeding with the fabrication of flight prototypes of the small composite LH2 dewar-tank,” said GTL President Paul Gloyer. “Our 28-inch diameter by 53-inch-long flight-type tank weighs only 15 kg, including inner tank, outer vacuum shell, multi-layer vacuum insulation, internal tubing, and sensors, but can hold 19 kg of LH2.”

This gives the GTL composites dewar-tank a hydrogen fraction (gravimetric index) of more than 55%, which is about 10x better than current hydrogen tanks. When stretched to carry 50 kg of LH2, the hydrogen fraction increases to over 62% with a mass of 30 kg, with larger versions able to achieve over 70% hydrogen fraction.

The GTL dewar-tank performance significantly exceeds the 35% hydrogen fraction goal needed for hydrogen to achieve parity with kerosene fuel (e.g., equal flight range). With GTL technology, hydrogen powered aircraft can exceed the performance of kerosene fueled aircraft, while eliminating carbon emissions and reducing cost per passenger mile by more than 25%.