Refrigeration Capacity Research Articles

Excellent Magnetocaloric Properties near 285 K of Amorphous Fe88Pr6Ce4B2 Ribbon

A novel amorphous Fe88Pr6Ce4B2 ribbon with better magnetocaloric properties near 285 K is reported in the present work. The Fe88Pr6Ce4B2 ribbon exhibits a typical second-order ferromagnetic–paramagnetic transition near its Curie temperature (Tc, ~284 K), with a maximum magnetic entropy change (−ΔSmpeak) of ~4.15 J/(kg × K) under 5 T and a maximum adiabatic temperature rise (ΔTad) of ~2.57 K under 5 T, both of which are almost the largest amongst the iron-based metallic glasses with Tc = 285 ± 10 K. The high −ΔSmpeak enables several amorphous hybrids with table-like −ΔSm–T curves to be synthesized by appropriately proportioning the Fe88Pr6Ce4B2 ribbon and other amorphous ribbons with different Tc. The larger average −ΔSm and effective refrigeration capacity, as well as the appropriate temperature range, make the two amorphous hybrids potential candidates for use as refrigerants in household magnetic air conditioners.

Advanced Exergy-Based Optimization of a Polygeneration System with CO2 as Working Fluid.

Using polygeneration systems is one of the most cost-effective ways for energy efficiency improvement, which secures sustainable energy development and reduces environmental impacts. This paper investigates a polygeneration system powered by low- to medium-grade waste heat and using CO2 as a working fluid to simultaneously produce electric power, refrigeration, and heating capacities. The system is simulated in Aspen HYSYS® and evaluated by applying advanced exergy-based methods. With the split of exergy destruction and investment cost into avoidable and unavoidable parts, the avoidable part reveals the real improvement potential and priority of each component. Subsequently, an exergoeconomic graphical optimization is implemented at the component level to improve the system performance further. Optimization results and an engineering solution considering technical limitations are proposed. Compared to the base case, the system exergetic efficiency was improved by 15.4% and the average product cost was reduced by 7.1%; while the engineering solution shows an increase of 11.3% in system exergetic efficiency and a decrease of 8.5% in the average product cost.

Refrigeration capacity modeling of europium titanate based magnetocaloric compounds using computational single hidden layer intelligent and random forest regression methods

Europium titanate (EuTiO3) is a quantum para-electric magnetocaloric compound with potential application in green magnetic cooling technology. Super-exchange and indirect interactions existing between the magnetic moments of this compound are responsible for the observed magnetic properties such as the refrigeration capacity which falls among the key factors that characterize the usefulness of magnetic system of cooling in addressing energy crisis. Crystallographic substitutions and ionic replacement potentially shift magnetic ordering between anti-ferromagnetism to ferromagnetism and ultimately alters the refrigeration (magnetic) capacity of EuTiO3 compound. This work proposes extreme learning machine (ELM) and random forest regression (RFR) computational approaches to model refrigeration capacity of europium titanate magnetic refrigerant with the aid of applied magnetic field, ionic concentrations and ionic radii predictors. Sigmoid activation based extreme learning machine algorithm(SGA-ELM) demonstrates superior performance over sine function activation based extreme learning machine algorithm(SIA-ELM) with improvement of 0.03 %, 16.04 % and 35.03 % on the basis of Pearson correlation coefficient (CC), root mean square error (RMSE) and mean absolute error (MAE) performance yardsticks, respectively on testing set of EuTiO3 based magnetocaloric compounds. SGA-ELM performs better than SIA-ELM and RFR model with improvement of 35.03 % and 66.84 %, respectively while SIA-ELM model performs better than RFR model with improvement of 59.97 %. SGA-ELM model developed in this work outperforms the existing swarm based support vector regression (SW-SVR) models with performance improvement of 15.38 % (for SW-SVR-Gas with Gaussian function) and 42. 71 % % (for SW-SVR-Pol with polynomial function) using mean absolute deviation (MAD) performance yardstick. Significance of magnetic field and dopants concentrations on refrigeration capacity of different EuTiO3 perovskite was investigated with SGA-ELM model. The accuracy of developed models in determining refrigeration capacity of EuTiO3 compounds would ultimately circumvents experimental challenges and explores future potentials of these classes of compound for addressing present and future energy crisis in cooling industries.

Experimental study of an absorption-based refrigeration driven by ocean thermal energy

Establishing an island-based cold chain is essential for ensuring food storage, vaccine preservation, and fish freezing on islands, which is indispensable for the sustainable development of island communities. The compression-absorption refrigeration system that uses ocean-thermal-energy is ideal for cold storage on islands as it efficiently utilizes local renewable energy sources and can meet refrigeration needs below 0 °C. Therefore, a refrigeration prototype has been constructed and thoroughly experimentally investigated to obtain refrigeration characterization under variations of refrigeration demand and environmental conditions. The system's energy-saving potential is evaluated by conducting comparisons with conventional refrigeration techniques. The results indicate that refrigeration temperature plays a crucial role in determining refrigeration capacity, with an increase of approximately 8.2 % observed for every 1 °C rise in refrigeration temperature. Lower cold-seawater temperatures or higher warm-seawater temperatures do not have a significant effect on the refrigeration capacity, but contribute to a reduction in compressor power due to increased thermally-driven compression force. Consequently, for every 1 °C change, the refrigeration capacity per unit compressor power increases by approximately 4 %. Additionally, the refrigeration capacity of the system is three times greater than that of a vapor-compression-refrigeration-system. The findings provide theoretical and experimental guidelines for the design and operation of refrigeration using ocean-thermal-energy.

Large cryogenic magnetocaloric effect in Na5Gd4F(SiO4)4

The adiabatic demagnetization refrigeration based on the magnetocaloric effect of magnetic materials has been regarded as an effective technology to attain sub-Kelvin temperature. In this article, the magnetic properties and MCE of Na5Gd4F(SiO4)4 compound are investigated. Due to the high Gd3+ ion/anion ligand ratio and weak magnetic interaction, Na5Gd4F(SiO4)4 exhibits a large magnetic entropy change of 49.6 J·kg−1·K−1 under magnetic field change of 0–7 T at 2.6 K, which surpasses the commercial magnetic refrigerant Gd3Ga5O12 under the same conditions. Besides, its refrigeration capacity and the relative cooling power under magnetic field change of 0–7 T reaches up to 308.9 J·kg−1 and 406.7 J·kg−1, respectively. These properties indicate that Na5Gd4F(SiO4)4 compound is a promising magnetic refrigeration material.

Structural, magnetic, and magnetocaloric characterizations of geometrically-frustrated SrRE2O4 (RE = Gd, Dy, Ho, Er) oxides for low-temperature cooling applications

The magnetocaloric (MC) properties of many rare earth (RE)-based magnetic solids have been intensively investigated. This research aims to develop suitable MC materials for low-temperature cooling application and to better elucidate their intrinsic properties. We have fabricated four single-phase SrRE2O4 (RE = Gd, Dy, Ho, Er) oxides and conducted a systematic experimental investigation into their structural, magnetic, and low-temperature MC properties. All these SrRE2O4 oxides crystallize in an orthorhombic structure (space group Pnma) and exhibit typical geometrical frustration. This frustration arises from the one-dimensional RE ion zigzag ladders along the c-axis, which link the two-dimensional honeycomb lattice in the ab plane. The elements in SrRE2O4 oxides are uniformly distributed and present with valence states of Sr2+, RE3+, and O2−, respectively. Large low-temperature MC effects and notable performances are realized in these SrRE2O4 oxides, determined by the MC parameters of magnetic entropy change, refrigerant capacity, and temperature-averaged entropy change (with a lift of 5 K). These MC parameters under a magnetic field change of 0–70 kOe are as follows: 34.18 J/kgK, 275.88 J/kg, and 30.74 J/kgK for SrGd2O4; 18.13 J/kgK, 253.83 J/kg, and 17.54 J/kgK for SrDy2O4; 18.81 J/kgK, 354.77 J/kg, and 18.61 J/kgK for SrHo2O4; and 22.63 J/kgK, 284.25 J/kg, and 21.97 J/kgK for SrEr2O4. These values are comparable to those of most recently updated low-temperature MC materials with remarkable performances, making these SrRE2O4 oxides highly interesting for practical cooling applications.

Critical behavior and tunable magnetocaloric effect in (Gd1-xErx)3Al2 alloys

The magnetic properties, magnetocaloric effect, and the critical behavior near Curie temperature (TC) were systematically studied in a series of (Gd1-xErx)3Al2 (x = 0, 0.1, 0.2, 0.3) alloys. As the Er content increases, both the TC and lattice constant gradually decrease. The maximum magnetic entropy change and refrigerant capacity remain relatively high, ranging from −5.8 to −8.5J/kg K and 209.0 to 290.8 J/kg respectively, for a field change of 5 T. The critical exponents, derived from the field dependence of magnetic entropy change, conform to scaling theory and are consistent with those obtained using the Kouvel–Fisher method. These findings suggest that the reliability of the obtained critical exponents and imply the presence of long-range exchange interactions in (Gd1-xErx)3Al2 alloys.

Structural, Magnetic, and Magneto-Thermal Properties of Rare Earth Intermetallic GdRhIn.

We study the structural, magnetic, and magneto-thermal properties of the GdRhIn compound. The room-temperature X-ray diffraction measurements show a hexagonal crystal structure. Temperature and field dependence of magnetization suggest two magnetic transitions-antiferromagnetic to ferromagnetic at 16 K and ferromagnetic to paramagnetic at 34 K. The heat capacity measurements confirm both the magnetic transitions in GdRhIn. The magnetization data were used to calculate isothermal magnetic entropy change and refrigerant capacity in GdRhIn, which was found to be 10.3 J/Kg-K for the field change of 70 kOe and 282 J/Kg for the field change of 50 kOe, respectively. The large magnetocaloric effect in GdRhIn suggests that the material could be used for magnetic refrigeration at low temperatures.

Development and Assessment of the Performance of a Novel Parabolic Trough Solar Collector-Driven Three-Stage Cooling Cycle

Abstract A gaseous flow is employed as heat transfer fluid (HTF) in a parabolic trough solar collector (PTSC) for simultaneous production of cooling at three different levels of temperature to meet the demands of air conditioning, refrigeration, and ultra-low-temperature refrigeration required to ensure the efficacy of some special vaccines. The combined system consists of five subsystems including PTSC, Kalina cycle (KC), ejector refrigeration cycle (ERC), cascaded refrigeration cycle (CRC), and absorption refrigeration cycle (ARC). A simulation through an engineering equation solver (EES) is conducted to assess the impact of internal tube diameter of absorber and solar irradiation on rise of HTF temperature and mass flowrate of Kalina cycle fluid. It is determined that for given solar irradiation, the temperature of HTF goes down when internal diameter of absorber tube is enlarged. The influence of weather conditions; solar irradiation and ambient temperature, type of HTF, and concentration of ammonia–water basic solution on thermal and exergy efficiencies of three-stage cooling cycle (TSC) are examined. The TSC with helium-operated PTSC delivers better results than air and CO2. Exergy analysis shows that solar collector (30.26%) dissipates the highest exergy, followed by the ejector (12.5%) and vapor generator subsystem (7.61%). The type of CRC fluid pair affects TSC cycle refrigeration capacity and cooling exergy efficiency. The promotion of solar irradiation from 850 to 1200 W/m2 increases the cooling exergy efficiency of the three-stage cycle from 6.72% to 9.52% when the evaporator temperature is set at −45 °C and CRC employs NH3-propylene.

Thermodynamic analysis of a modified two-stage transcritical CO2 refrigeration cycle with an ejector and a subcooler

In the application scope of large-scale supermarkets, the practicality of transcritical CO2 refrigeration device has been confirmed to be quite satisfying. A modified two-stage transcritical CO2 refrigeration cycle with an ejector and a subcooler (MTC) is proposed in this paper. In the modified cycle, the ejector recovers expansion works and reduces irreversible losses in the throttling process. The subcooler provides subcooling degree for the CO2 entering the low-temperature (LT) evaporator, thus increasing the refrigeration capacity and improving the COP of the modified cycle. Thermodynamic analysis has shown that the exergy efficiency (ηex) and COP of MTC under given operating condition has been enhanced by 13.7 % and 14.2 % compared to BTC. The discharge temperature at the outlet of high-pressure compressor in MTC is decreased by 8.3℃. Under typical operating condition, the optimal discharge pressure of MTC is 9.07 MPa, which is lower than that of BTC. The correlation to calculate optimal discharge pressure for single-stage CO2 refrigeration cycle is also suitable for MTC under given operating conditions. The MTC has also shown better performance under variable operating conditions. For MTC, when the temperature at the outlet of gas cooler increases from 35 – 45℃, the COP and ηex are enhanced by 14.1 % - 16.1 % and 12.8 % - 14.2 % compared to BTC, respectively. When gas cooler outlet pressure decreases from 11.0 to 7.5 MPa, the COP and ηex are enhanced by 14.0 % - 22.8 % and 13.4 % - 18.7 %. As the evaporating temperature at the cold side of subcooler increases from -25 to -15℃, the COP and ηex increase from 1.82 to 1.98 and 27.4 % to 29.7 %. With the ratio of refrigeration capacity (Rec) between medium-temperature evaporator and low-temperature evaporator varies from 0.7 to 1.2, the COP and ηex are improved by 10.7 % - 16.3 % and 10.7 % - 15.4 % compared to BTC. There is the maximum exergy loss at gas cooler in the MTC, whereas that of BTC is located in the expansion valve before LT evaporator. The economic analysis shows the cost per unit of exergy of MTC is decreased by 11.5 % under typical operation condition. According to simulation results, the modified cycle has better performance in severe working conditions such as high gas cooler outlet temperature and low gas cooler outlet pressure in the given range of working conditions compared to BTC.

Excellent magnetocaloric effect near the hydrogen liquefaction temperature of a binary Er67.5Co32.5 metallic glass

We reported the excellent magnetocaloric effect of a binary Er67.5Co32.5 metallic glass (MG) near the hydrogen liquefaction temperature. The binary MG ribbon was fabricated by a melt-spinning method. The Er67.5Co32.5 alloy exhibits a better glass formability than most of other rare earth (RE)-Co binary alloys. The maximum magnetic entropy change (−ΔSmpeak) and refrigeration capacity (RC) of the Er67.5Co32.5 amorphous ribbon under 0–5 T reach to 17.47 J/(kg × K) near its Curie temperature (Tc, ∼ 11 K) and 472 J/kg, both of which are rather high among the RE-based MGs with a Tc around 10 K and imply the potential application perspective as magnetic refrigerants for hydrogen liquefaction. The magnetization as well as magnetocaloric behaviors of the binary MG were observed, and the mechanism involved was investigated.

Comparison and analysis on comprehensive performance of CO2 multiphase refrigeration systems using liquefied natural gas cold energy

In order to fully apply liquefied natural gas (LNG) cold energy to the refrigeration system, four different types of CO2 multiphase refrigeration systems using LNG cold energy are designed. In this paper, (1) CO2 single-stage compressed solid and gas phase refrigeration cycle (SSCC1), (2) CO2 single-stage compressed solid and solid phase refrigeration cycle (SSCC2), (3) CO2 double-stage compressed solid and gas phase refrigeration cycle (DSCC1), and (4) CO2 double-stage compressed solid and solid phase refrigeration cycle (DSCC2) are combined with CO2 liquid phase secondary refrigerant cycle (RC), respectively, to effectively use LNG cold energy. The performance analysis, exergy analysis, economic analysis, and CO2 emission analysis of the proposed systems are carried out by establishing the mathematical models. The results show that the intermediate pressure of DSCC1-RC and DSCC2-RC reaches the best performance at 0.3 MPa, and the system performance decreases with the increase in intermediate temperature. The refrigerating capacity of the CO2 liquid phase secondary refrigerant cycle, the COP, and the exergy efficiency of four kinds of CO2 multiphase refrigeration systems decrease with the increase in the refrigerating capacity of the CO2 refrigeration cycle, while the power consumption of SSCC2-RC and DSCC2-RC decreases, SSCC1-RC and DSCC1-RC increased. The system with the shortest exergy loss is DSCC2-RC at 654.01 kW, while the system with the shortest payback period is SSCC2-RC at 0.88 years, and DSCC2-RC has the smallest CO2 emission. Four CO2 multiphase refrigeration systems and the ammonia combined refrigeration system with the same total refrigerating capacity are compared and analyzed, respectively; the results show that the performance, economy, and CO2 emission of CO2 multiphase refrigeration system are better than those of ammonia combined refrigeration system; and the exergy loss of CO2 multiphase refrigeration system is generally larger than that of ammonia combined refrigeration system because of the large temperature difference in heat transfer.

Comparative analysis of radiant air-conditioning systems combined with two different types of solar-powered dehumidification methods

Abstract This paper proposes a solar liquid desiccant radiation air-conditioning system(SLDRS) and a solar desiccant wheel radiant air-conditioning system(SDWRS) that combine with a phase change energy storage radiation terminal, solar energy, and heat pump system. The models of the two systems are simulated with the transient system tool (TRNSYS) to compare the refrigeration and dehumidification effects and energy saving of the two systems. The results show that the total refrigeration capacity of the SLDRS is reduced by 20.45% compared with the solar desiccant wheel radiation air-conditioning system, the monthly average dehumidification capacity is increased by 37.09%, and the total energy consumption is reduced by 712.9 KW·h. It is evident that the cooling and dehumidifying effect and energy efficiency of the SLDRS are superior to those of the SDWRS.

Energy storage efficiency and electrocaloric performances in lead-free Ba0.87Ca0.13(Ti0.9Zr0.1)0.98(Zn1/3Nb2/3)0.02O3 ceramic

Ba0.87Ca0.13(Ti0.9Zr0.1)0.98(Zn1/3Nb2/3)0.02O3 ceramic was prepared using a solid-state reaction method. This work investigates their dielectric, ferroelectric, energy storage, and electrocaloric properties. X-ray diffraction analysis confirms a pure perovskite structure. The dielectric constant reaches a maximum of 9364 at 326 K. Enhanced total energy density, recovered energy density, and energy storage efficiency are observed between 303 K and 363 K. Artificial neural networks (ANNs) are employed for the indirect determination of large ECE and responsivity based solely on measured ferroelectric polarization (P(E,T)). This approach offers rapid and accurate predictions with minimal experimental data, significantly accelerating the characterization of novel electrocaloric materials. The maximum ECE occurs above the Curie temperature (TC) and increases with higher electric fields. The ceramic exhibits significant ECE parameters around TC with a broad electrocaloric temperature span. Various figures of merit, including relative cooling power, refrigerant capacity, and temperature-averaged entropy change, are explored under different electric fields, demonstrating the material's potential for green cooling devices. These figures improve monotonically with increasing field strength. A comprehensive analysis of the field dependence of ΔS (entropy change) confirms the second-order nature of the electric phase transition through master curve analysis. In conclusion, these lead-free ceramics exhibit promising applications in high-performance energy storage devices and solid-state refrigeration technology.

Impact of magnetic, atomic and microstructural ordering on the magnetocaloric performance of powdered NiCoMnSn metamagnetic shape memory ribbons

Co-doped NiMnSn Heusler-type metamagnetic shape memory alloys (MMSMAs) are promising materials for the next-generation solid-state refrigeration systems due to their excellent magnetocaloric performance around the martensitic transformation, which is easily tuneable by slight changes in the alloy composition. An improvement in the thermal efficiency of active magnetic regenerator devices, a key element in magnetocaloric cooling systems, arises by obtaining powdered magnetocaloric alloys that meet technical requirements for their implementation as a feedstock material in the additive manufacturing of 3D-printed heat exchangers. In the present work, powders of Mn-rich NiCoMnSn Heusler-type MMSMAs were obtained from their ribbon form avoiding or minimizing residual stresses, the number of defects and disorder in the crystal lattice and microstructure. Since atomic order and crystallographic structure are crucial in the transformation and magnetic properties of these alloys, a complementary structural analysis of the powders after different heat treatments was performed by powder neutron diffraction. The results show that the cubic austenitic phase of the non-heat-treated melt-spun powder exhibits a highly stressed structure, which leads to an incomplete martensitic transformation and, therefore, to the coexistence of martensitic and austenitic phases at low temperatures. The magnetic structure of the austenite phase was also determined by neutron powder diffraction, obtaining a ferromagnetic coupling between 4a and 4b Wyckoff positions in the samples analysed. It was found that a heat treatment facilitates the martensitic transformation and enables the formation of a pure martensitic phase.The observed changes in the magnetocaloric performance of the powders have been understood in terms of the differently stressed structures and their impact on the martensitic transformation. A fully completed structural transformation leads to a significant increase of the magnetisation change across the martensitic transformation and, consequently, to high values of both a magnetic field induced isothermal entropy change and refrigeration capacity.

Refrigerant charge influence on the performance of a transcritical CO2 system with flash-tank for low-temperature refrigeration

While the use of CO2 as a natural refrigerant become widespread, there is a scarcity of research on refrigerant charge effects in transcritical CO2 refrigeration applications, especially for systems with flash-tank and two-stage compressors. In this work, an experimental investigation of the effect of the Normalized Refrigerant Charge (NRC) on the parameters and performance of a Flash-Tank Vapor Injection (FTVI) CO2 refrigeration system is carried out. Within the explored NRC range of −0.02 to 0.247, an optimal NRC of 0.18 was identified that yields a maximum COP regardless of operating conditions. Results suggest that typical operating parameters such as temperature and pressure are not being affected by the NRC because of the charge buffering function of the flash-tank. However, the liquid–vapor separation capacity of the flash-tank causes a reduction in the refrigeration capacity when the system is not charged properly. This refrigeration capacity detriment related to undercharged conditions becomes more severe under high ambient temperatures, with a maximum COP penalty of 20 % when comparing the lowest charge versus the optimal charge performances at a gas cooler outlet temperature of 40 °C.

Identifying effective parameters on capillary tube performance with HCFCs, HFCs blends, and hydrocarbon refrigerants: Numerical assessment

This work offers a comprehensive numerical evaluation of the performance of capillary tube utilizing different refrigerants, including HCFCs, HFCs blends (Zeotropic, Azeotropic), and hydrocarbon, such as such as R22, R404A, R407C, R410A, R507A, and R290 refrigerants to predict the critical length of the adiabatic capillary tube. Utilizing a comprehensive thermodynamic model is applied to simulate the behavior of different refrigerants. Moreover, the effective design parameters based on the internal diameter for the adiabatic capillary tube (ACT), inside surface tube roughness, degree of subcooled, metastable region, condenser diameter, design of evaporator pressure (at critical length), condenser operating pressure, and refrigeration capacity are considered. The numerical model is developed based on the governing equations for mass, momentum, and energy, while a specified empirical equations are employed to represent each of the friction factor for single-and-two phase flow and metastable region. The results showed that the longest length of the ACT of 10.5 m revealed with R410A at mass flow rate of 8 g/s compared with 0.25 m at mass flow rate of 16 g/s for R290. Also, the results showed that the minimum value of friction factor of 0.0189 for R410A compared with maximum value of 0.0208 for R407C. The developed model is validated with available experimental results and models under different operation conditions and is found expectable with a good agreement. Where the standard error for different refrigerant with range value between (2.774% to 3.677%). However, the model represents accurate prediction the flow behavior and the thermal performance of the ACT.

Multi-phase transition behavior over a wide temperature range in magnetocaloric (Mn, Fe, Ni)2(P, Si) alloys

This study investigates the magnetocaloric property of MnFe0.95-xNixP0.6Si0.4 (x = 0.02, 0.03, 0.04) alloys over a wide temperature range and their related phase transitions. These P-rich composition alloys, with a P/Si ratio of 1.5, exhibit multi-phase transition behavior across a broad temperature range. In-situ 2D X-ray diffraction reveals overlapping diffraction peaks of the Fe2P-type hexagonal structure throughout the ferromagnetic-paramagnetic transition, rather than a single, drastic transition. This observation suggests the formation of a multi-phase structure within the alloys. Consequently, these alloys exhibit high refrigeration capacity (RC) values ranging from 168.6 to 218.1 J kg−1 under an applied magnetic field of 2 T. Notably, these RC values are superior to those observed in other P/Si ratio compositions without multi-phase transitions or even Gd, a representative magnetocaloric material. This improved performance demonstrates the promising potential of these multi-phase transition alloys as candidates for magnetocaloric refrigeration systems.

Enhanced magnetic refrigeration capacities of Er6FeSb2 by manganese substitution

Er6FeSb2 is a potential magnetic refrigeration material that can work at the liquid hydrogen temperature range. This work enhances the magnetic refrigeration performance of Er6Fe1-xMnxSb2 by Mn substitution. Mn doping increases the cell volume while maintaining the compound’s crystal structure type. It also results in an increase in the charge density distribution between Er1 and Fe/Mn. As the Mn content increases, the ferromagnetic exchange is enhanced, and the TC continuously increases. The Mn doping induces spin reorientation at low temperature, transforming compounds from traditional magnetocaloric effects to table-like magnetocaloric effects, greatly enlarge the cooling temperature range. When the content of Mn increases from x = 0 to x = 0.3, the δTFWHM increases from 26 K to 62 K, the −(ΔSM)max decreases from 12.1 J/(kg·K) to 5.9 J/(kg·K), and the RCP first increases and then decreases, reaching the maximum value of 435.0 J/kg at x = 0.2. This study opens a new path for the search of magnetic refrigeration material with large cooling temperature range.

HoDyGdCoAl high-entropy amorphous alloys working at full temperature range for hydrogen liquefaction with large magnetocaloric effects

Cryogenic magnetic refrigeration materials based on magnetocaloric effect can be used for hydrogen liquefaction. In this work, glass formation ability (GFA), magnetocaloric effect (MCE), refrigeration performance of melt-extracted HoDyGdCoAl amorphous ribbons have been investigated. Amorphous ribbons undergo a second order magnetic phase transition which achieve a table-like behavior broaden the range of magnetic transition temperature in hydrogen liquefaction.The maximum magnetic entropy change (-ΔSmaxM), the δTFWHM and the refrigeration capacity (RC) achieved 10.9 J/ (kg K), 84.2 K and 742.4 J/ kg (x = 5) and 11.2 J/ (kg K), 69.8 K and 643.0 J/ kg (x = 20) under a magnetic field change of 7 T, respectively. Combining wide magnetic transition temperature and large refrigerant capacity, the present amorphous ribbons can be used as potential magnetic refrigerant materials in hydrogen liquefaction temperature region.