2017-06-20

Vapor-Cooled Cryogenic Tanks

Description

For UAV manufacturers who require reliable, long endurance flight, liquid hydrogen can enable 8-hour flight times, high reliability, and 5x longer maintenance intervals compared to gasoline fueled propulsion systems. The result is fewer UAVs needed for a mission, increased reliability, and reduced operating costs.

Low boil-off liquid hydrogen storage tanks exist for laboratory and ground based use. However the current technology cannot be directly transferred to use in unmanned aircraft systems where weight is a critical design parameter. Current cryogenic tanks are made of stainless steel or aluminum and must be vacuum jacketed to reduce the boil-off. Aside from the tank, additional weight from a heat exchanger is required to warm the cold boil-off vapors to near ambient temperature before entering the fuel cell. This configuration is unsuitable for use in weight sensitive applications.

We have capitalized on the unique ability of additive manufacturing to combine complex geometries and lightweight materials to develop a liquid hydrogen storage tank that can be optimized for different UAV platforms. Overall system mass is reduced by incorporating the heat exchanger into the tank wall, warming the cold hydrogen vapor to ambient temperature before it leaves the tank. The structural polymers we utilize have a density 1/3 of that of aluminum and provide adequate strength for a low pressure liquid cryogen tank (~30 psig).

Features – Current energy storage solutions for electric propulsion are shown below.

As shown in the comparison above, our lightweight 3D printed tank enables UAV operators to use the highest specific energy fuel for electric powered flight over other forms of energy storage technology. For liquid hydrogen storage, no metal based tank can match our tank’s specific energy or gravimetric capacity.

Specifications – Our design targets Group 2 UAVs (20-55 lbs.) and can be expanded to meet the needs of Group 3 UAVs (< 1320 lbs.) for both military and industrial cases. By utilizing 3D printing our tank can be quickly designed and rapidly manufactured to suit different platforms. We can custom design a tank for optimal efficiency with specific airframes or even specific mission objectives to meet our customer’s needs.

 

Top