Researchers from the University of Technology Sydney (UTS) and the Queensland University of Technology (QUT) have devised a novel technique for accelerating the charging of solid-state hydrogen fuel cells.
Hydrogen is garnering a great deal of interest as an effective way to store ‘green energy’ from renewable sources such as wind and solar. Hydrogen is most frequently kept as a compressed gas, although it may also be stored as a liquid or solid.
Dr. Saidul Islam of the University of Technology Sydney stated that solid hydrogen storage, and in particular metal hydride, is drawing interest since it is safer, more compact, and less expensive than compressed gas or liquid, and can reversibly absorb and release hydrogen.
“Metal hydride hydrogen storage method is optimal for on-site hydrogen generation from renewable electrolysis.” It can store hydrogen for extended periods, and when needed, it can be transformed by a fuel cell into either a gas or a type of heat or electrical energy.
“Applications for this technology include hydrogen compressors, rechargeable batteries, heat pumps and heat storage, isotope separation, and hydrogen purification. It can also be used to store hydrogen in orbit for use in satellites and other “green” space technologies, he explained.
However, metal hydride’s poor heat conductivity, which results in delayed charging and discharging periods, has been a challenge for hydrogen energy storage.
To overcome this issue, researchers devised a new way for enhancing solid-state hydrogen charging and discharging periods. The work, entitled “Design optimization of a magnesium-based metal hydride hydrogen energy storage device,” was just published in Scientific Reports.
PhD candidate Puchanee Larpruenrudee of the UTS School of Mechanical and Mechatronic Engineering said that quicker heat evacuation from the solid fuel cell resulted in faster charging periods.
“Numerous heat exchangers have been created for use with metal hydride hydrogen storage. These include straight tubes, tubes with a helical coil or spiral, U-shaped tubes, and fins. The use of a helical coil considerably enhances heat and mass transport within the storage.
This is the result of secondary circulation and a larger surface area for heat transfer from the metal hydride powder to the cooling fluid. Our research resulted in the development of a helical coil to improve heat transmission.”
Researchers created a semi-cylindrical coil for use as an internal heat exchanger, which greatly enhanced heat transfer performance. Using the novel semi-cylindrical coil as opposed to a conventional helical coil heat exchanger decreased the time required to charge hydrogen by 59%.
Currently, they are simulating the hydrogen desorption process numerically and attempting to optimize absorption times. The semi-cylindrical coil heat exchanger will be improved further for this purpose.
Finally, the researchers intend to create a novel architecture for hydrogen energy storage that combines several types of heat exchangers. In addition, they intend to collaborate with industry partners to examine the novel heat exchanger’s impact on actual tank performance.