A Single Step from Liquid Hydrogen Production to Safety Values Testing

The Hydrogen Electric Research Team at the Korea Electrotechnology Research Institute (KERI) has developed the world's first integrated system capable of producing liquid hydrogen and evaluating the performance of safety valves in a single step. This significant achievement, announced just in time for the celebration of "Hydrogen Day" (November 2, designated by the Ministry of Trade, Industry and Energy as the day symbolizes H2, the chemical symbol for hydrogen), is expected to attract considerable attention from the industry as it promotes the hydrogen economy.

Liquid hydrogen is produced by cooling hydrogen gas to an extremely low temperature (–253°C), resulting in a volume 800 times smaller than its gaseous form. It has advantages in improved safety during storage, which increases public acceptance in terms of transportation, liquid hydrogen allows for a much larger and safer volume of hydrogen to be transported compared to its gaseous form, which could greatly accelerate the nationwide distribution of hydrogen.

Beyond production, hydrogen entails many technological challenges. Ensuring cryogenic conditions and consistently managing the internal pressure of hydrogen tanks is essential for the long-term storage and transport of liquid hydrogen. The quality of relevant components is also critical. Among these components, safety valves play a crucial role in regulating pressure. When the internal pressure of a tank exceeds a certain threshold, safety valves automatically release hydrogen gas at high pressure to regulate pressure.

The challenge for domestic manufacturers has been that the production and distribution infrastructure for liquid hydrogen is not yet fully established. As a result, manufacturers have faced difficulties in verifying product quality solely through the efforts of safety valve manufacturers. With limited access to liquid hydrogen, manufacturers have had to rely on more accessible but less effective alternatives such as liquid nitrogen or the more expensive liquid helium to perform incomplete performance tests.

The inability to adequately verify the performance of safety valves with ample access to liquid hydrogen, and the resulting proliferation of inferior safety valves in the marketplace, could pose a risk of serious accidents. To overcome this challenge, KERI has developed a breakthrough device to perform both liquid hydrogen production and safety valve performance evaluation in one integrated system. This system enables efficient and seamless testing by producing liquid hydrogen and immediately testing the components’ performance.

KERI has already established itself as a leader in liquid hydrogen technology with the development of an automatic cryogenic cooling technology, known as "Zero Boil-off^*," which enables the efficient production and long-term storage of liquid hydrogen. Building on this expertise, KERI’s research team has now successfully developed a system that expands their technological capabilities to include safety valve performance testing.
^{* Zero Boil-off: an advanced cryogenic cooling technology that ensures any vaporized hydrogen within a liquid hydrogen storage tank is fully recondensed back into liquid form, maintaining zero loss of liquid hydrogen during storage.}

The newly developed device is designed to evaluate the performance of safety valves for 3-ton liquid hydrogen tank trailers. Its portable design allows for easy installation and operation by companies. In addition, the device has undergone rigorous safety testing in the explosion-proof test chamber of KERI, an internationally accredited electrical equipment testing and certification body.

Rock-kil Ko, the Director of the Hydrogen Electric Research Team at KERI, explained, “Even globally, there are concerns among experts about the lack of proper safety valve performance evaluation under real-world settings for liquid hydrogen testing. Our device allows for the safe and simple production of liquid hydrogen and the evaluation of safety valves in one system, even in small spaces. This will significantly enhance the competitiveness of the nation’s hydrogen industry.”

KERI plans to conduct further experiments to upgrade the functionality of the device, allowing it to handle larger pressures and volumes of hydrogen. The institute will also work closely with organizations such as the Korea Gas Corporation to ensure the device meets all necessary requirements for use in safety valve performance evaluations by accredited testing bodies. Furthermore, KERI is anticipating strong interest in this breakthrough from liquid hydrogen component manufacturers and evaluation device makers, with potential for technology transfers.

This research project was conducted with the funding support of the Ministry of Trade, Industry, and Energy and the Korea Institute of Energy Technology Evaluation and Planning for the "3,000 kg Capacity Tank Trailer Development and Demonstration Project for Liquid Hydrogen Transportation."

<KERI is a government-funded research institute under the National Research Council of Science and Technology of the Korean Ministry of Science and ICT.>