# Fileset

[cssj_Gado.pdf](https://mdr.nims.go.jp/filesets/f100dca1-feb5-40f5-a205-58783d01078a/download)

## Creator

[Mohamed Gado](https://orcid.org/0000-0002-5293-5532), Tsuyoshi Shirai, [Kyohei Natsume](https://orcid.org/0000-0003-3949-6923), [Akira Uchida](https://orcid.org/0000-0002-9193-054X), Takenori Numazawa, [Koji Kamiya](https://orcid.org/0000-0002-6765-4485)

## Rights

[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

## Other metadata

[Evaluation of magnetic hydrogen liquefaction system using potential magnetocaloric materials](https://mdr.nims.go.jp/datasets/416e26de-9e4c-4cdd-aba4-76f296b4460b)

## Fulltext

講演概要の書き方（14ポイント）有望な磁気熱量効果材料を用いた磁気水素液化システムの評価 Evaluation of magnetic hydrogen liquefaction system using potential magnetocaloric materials  ガド モハメド，白井 毅, 夏目 恭平, 内田 公, 沼澤 健則, 神谷 宏治（物材研） Mohamed Gado，Tsuyoshi Shirai, Kyohei Natsume, Akira Uchida, Takenori Numazawa, Koji Kamiya  (National Institute for Materials Science)  E-mail: mohamed.gado@nims.go.jp  1．Introduction Magnetic refrigeration systems are widely recognized as efficient, compact, and environmentally friendly, given their trivial effect on ozone-depleting or greenhouse gases (e.g., CFCs, HFCs, and HFOs). After the success of liquefying hydrogen by Sir James Dewar in the late 19th century, several liquefaction technologies have been developed. Conventional liquefaction systems involve Joule–Thomson and turbine expansion systems. However, those systems are energy-intensive, which entails about 10–20 kWh/kg for H2 liquefaction. Magnetic refrigeration systems have recently been employed as a potential alternative to conventional liquefaction systems. Magnetic refrigeration relies on the magnetocaloric effect (MCE), whereby the temperature of a magnetic material changes in response to variations in the magnetic field [1]. This study targets examining different magnetocaloric materials for H2 liquefaction. 2．System description and principles The AMR cycle includes four processes: (i) magnetization, (ii) cold-to-hot blow, (iii) demagnetization, and (iv) hot-to-cold blow (cf. Fig. 1). During the cold-to-hot end, the helium flow is allowed to reject heat to the hot-end heat exchanger (HHEX). During the hot-to-cold blow, helium gas is used to cover a cooling load via the cold-end heat exchanger (CHEX). Consecutive cycle operations enable a continual cooling effect. (a) MagnetizationCold endHot end(b) Cold-to-hot blowCold endHot end(c) DemagnetizationCold endHot endMagnetHeMCMCHEX(d) Hot-to-cold blowCold endHot endHHEX Fig.1 AMR cycle principles.    Different magnetocaloric materials have been proposed for hydrogen liquefaction. Amongst them, HoAl2, HoB2, and ErAl2 have a strong MCE near to the hydrogen liquefaction temperature of 20.3 K [2]. Each candidate has its local operating temperature ranges between the heat rejection and absorption reservoirs. In Fig. 2, HoAl2 shows a strong MCE near to the hot-end temperature of 30 K. Besides, it has a wide distribution of MCE, making it more suitable for hydrogen liquefaction applications. However, HoAl2 can be more expensive than ErAl2, but cheaper to HoB2.  Fig.2 Entropy change for HoAl2, HoB2, and ErAl2, at a magnetic field change of 0-5 T. 3．Methods A transient axisymmetric two-dimensional model of the active magnetic regenerator (AMR) was developed and solved via COMSOL Multiphysics 6.4. The AMR regenerator is homogeneously packed with different magnetocaloric particles with a particle diameter of 300 μm, and subjected to a peak magnetic flux intensity of 5 T. 4．Results and discussion Figure 3 illustrates the effect of mass flow rate from 80 to 160 g/s on cooling capacity (QC), coefficient of performance (COP), figure of merit (FOM), and hydrogen production for HoAl2, HoB2, and ErAl2 materials, under peak 5 T. As mass flow rate increases, QC rises for all materials, with HoAl₂ showing the highest values (55–112 W), while ErAl2 and HoB2 remain significantly lower. The COP plot indicates that HoAl2 maintains superior efficiency (1.03–1.22), whereas ErAl2 slightly decreases and HoB2 gradually increases but stays below 0.25. Similar to the COP trend, the FOM reaches 61% for HoAl2, while attaining a hydrogen liquefaction yield of 20 kg/day for HoAl2, compared with 7.5 kg/day for ErAl2 and 7.6 kg/day for HoB2. HoAl2 can attain a minimum cold-end temperature of 16.6 K, compared to 8.6 K for HoB2 and 8 K for ErAl2, making HoB2 and ErAl2 more suitable for lower cold-end temperatures. Overall, HoAl2 demonstrates the best thermodynamic and hydrogen generation performance.  Fig.3 performance of HoAl2, ErAl2, and HoB2: cooling power, COP, FOM, and hydrogen liquefaction yield.   Acknowledgement This work is supported by the JST-Mirai Program Grant Number JPMJMI18A3, Japan, and the JSPS KAKENHI Grant.  References 1. K.A. Gschneidner, V.K. Pecharsky: Int. J. Refrig. Vol. 31 (2008) pp.945–961. 2. M.G. Gado, T. Shirai, Y. Yoshida, A. Uchida, T. Hirayama, T. Numazawa, K. Natsume, K. Kamiya: Cryogenics (Guildf). Vol.158 (2026) PP.104347.