GTL. Gloyer-Taylor Laboratories Inc, is a specialist composite manufacturer and it validates LH2 composite dewar tanks for use in aviation. Recently, they shared that, “In-depth results from the successful validation testing of its small, subscale composite vacuum jacketed dewar tank with liquid hydrogen (LH2).”
Think of a dewar as a large thermos bottle and you won’t be far from reality. “A cryogenic storage dewar (or simply dewar) is a specialized type of vacuum flask used for storing cryogens (such as liquid nitrogen or liquid helium), whose boiling points are much lower than room temperature. It is named after inventor James Dewar, who developed it for his own work. They are commonly used in low-temperature physics and chemistry.” (Wikipedia)
The company explained, “Test results exceeded expectations regarding holding hard vacuum, heat load, rapid chill-down and hydrogen fraction goal, leading to flight prototype fabrication. “
Light weight tanks enable carrying sufficient H2 for long flights. Composite dewar tank technology. Source | Gloyer-Taylor Laboratories (GTL)
The company reports, “When fully isolated, the dewar tank held hard vacuum at 2.8.e-6 torr (5.414e-9 psi) for approximately 50 minutes with LH2, which was the company notes is >100 times better than the requirement. This enabled the GTL dewar tank to hold LH2 for more than 21 hours, at -430°F while remaining leak tight with minimal hydrogen permeation. During this test, the subscale 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.”
An impressive achievement for hydrogen powered aircraft, whose tank weights often are significantly heavier than that of their contents.
Lightweighting
GTL’s 28-inch-diameter by 53-inch-long flight-type tank weighs only 15 kilograms, including inner tank, outer vacuum shell, multilayer vacuum insulation, internal tubing and sensors, but can hold 19 kilograms of liquid hydrogen. That means the tank is 10 times lighter than equivalent units. This gives the opportunity to carry enough hydrogen to enable truly long flights while lowering overall weight.
The company reports even better results with larger tanks. A tank holding 50 kilograms (110 pounds) the H2 is only 38 percent of the total weight. GTL claims larger tanks will manage a 70-percent hydrogen fraction.
GTL’s connections to ZeroAvia, Hypoint, and PowerCell are important to ensuring range for H2 aircraft approach or equal that of fossil fuel powered craft. These lightweight tanks are a major part of that achievement and a grand achievement in themselves.