Tino Gottschall, HLD Dresden.
We are witnessing a great transition towards a society powered by renewable energies to meet the ever-stringent climate target. Hydrogen, as an energy carrier, will play a key role in building a climate-neutral society. Although liquid hydrogen is essential for hydrogen storage and transportation, liquefying hydrogen is costly using conventional methods based on Joule-Thomson effect. As an emerging technology which is potentially more efficient, magnetocaloric hydrogen liquefaction can be a “game-changer” here. In this work, we have investigated the rare- earth-based Laves phases RAl2 and RNi2 (R being a rare earth) for magnetocaloric hydrogen liquefaction. We have noticed an unaddressed feature that the magnetocaloric effect of second-order magnetocaloric materials can become “giant” near the hydrogen boiling point. This feature indicates strong correlations, down to the boiling point of hydrogen, among the three important quantities of the magnetocaloric effect: the maximum magnetic entropy change ΔSm, the maximum adiabatic temperature change ΔTad, and the Curie temperature Tc. Results of our measurements of the magnetocaloric effect in static and in pulsed fields are shown in the figure. Moreover, we have developed a mean-field approach to describe these two trends theoretically. The dependence of the magnetocaloric effect on Tc revealed in this work helps researchers quickly anticipate the magnetocaloric performance of rare-earth-based compounds, guiding materials design and accelerating the discoveries of magnetocaloric materials for hydrogen liquefaction.
Figure: (a) Magnetic entropy changes in fields of 5 T and (b) direct measurements of adiabatic temperature changes of several Laves-phase materials in pulsed fields of 2, 5, and 20 T
A study on rare-earth Laves phases for magnetocaloric liquefaction of hydrogen, W. Liu, E. Bykov, S. Taskaev, M. Bogush, V. Khovaylo, N. Fortunato, A. Aubert, H. Zhang, T. Gottschall, J. Wosnitza, F. Scheibel, K. Skokov, and O. Gutfleisch, Applied Materials Today 29, 101624 (2022).
https://www.sciencedirect.com/science/article/abs/pii/S235294072200258X
Contact:t.gottschall@hzdr.de
