International Journal of Energy Research最新文献

This study explores the innovative recycling of neodymium (Nd) permanent magnet scrap to synthesize Fe₃O₄, a high-capacity anode material for secondary batteries, by leveraging the Fe oxalate solution produced during recycling. The traditional process of recovering Fe from permanent magnets in the form of oxides produces products with limited economic viability and usability. For the first time, we have successfully synthesized Fe₃O₄ as an anode material for lithium-ion (Li-ion) secondary batteries from scrap Nd magnets. We address the existing challenge by employing a novel approach: hydrothermal synthesis of crystalline FeC₂O₄·2H₂O from the Fe leachate, extracted via oxalic acid leaching from a mixed phase of NdF₃-Fe₂O₃ controlled during fluorination heat treatment while recycling. The recovered FeC₂O₄·2H₂O is subsequently phase-transferred to Fe₃O₄ under an Ar atmosphere. To overcome the inherent low conductivity and rate capability of Fe₃O₄, a carbon-coating process utilizing dopamine HCl is implemented. The developed C-Fe₃O₄ anode material exhibits a significant capacity retention of 428 mAh/g after 500 cycles at 1C, showcasing its potential for use in high-performance secondary batteries and contributing to the sustainable recycling of critical materials.

In molten salt reactors (MSRs), a small amount of inert gas could be entrained from the free liquid surface to the primary loop, which may have obvious impacts on the heat transfer performance of the heat exchanger, the reactivity of the core, and the migration of insoluble fission products. It is necessary to understand how the bubbles flow into the reactor core, and what kinds of size distribution should they be. Meanwhile, the heat exchanger is an important and complicated place before the gas enters the core, in which the bubbles may exhibit complex behavior, such as coalescence, breakup, or retention. This research employs a coupling method between the Eulerian two-phase flow model (ETFM) and the population balance model (PBM) to simulate the two-phase flow of bubbles entrained in molten salt on the shell side of a vertical U-tube heat exchanger. The gas fraction and poly-dispersed bubble size distribution are analyzed under different calculation methods and input conditions. The results show that the distribution of gas volume fraction and bubble size are significantly influenced by the characteristics of the flow field, and the salt flow can also be affected by the bubble distribution. The bubbles exhibit obvious non-uniformity distribution, especially in the center of the separation and the backflow vortexes, and a significant accumulation of gas attachment occurs behind the baffles. The interfacial area concentration and surface heat transfer coefficient are also discussed with or without the bubble distribution. All indicate that a precise bubble spatial and size distribution is necessary when in the simulation of multiphase flow in MSRs.

The effect of low-dose gamma-ray irradiation on an amorphous SnO₂ electron-selective layer (ESL) was investigated in this study. Further, its impact on the photovoltaic (PV) performance of planar perovskite solar cells (PSCs) based on MAPbI₃ and CsFAMAPbIBr absorber layers has been evaluated for the first time. The properties of the SnO₂ layer were substantially modified by the gamma-ray irradiation of regulatory exemption radioactive sources (Co-60). Gamma-ray irradiation promoted the formation of large perovskite grains by creating a hydrophilic surface via the generation of ─OH on the amorphous SnO₂ film surface. In addition, gamma-ray irradiation increased the conductivity of the SnO₂ layer due to the generation of the proper oxygen vacancies in SnO₂. From the optimization of gamma-ray irradiation parameters, we achieved a best efficiency of 18.03% using the MAPbI₃ perovskite film owing to the enhanced perovskite densification and increased SnO₂ conductivity. This efficiency was significantly improved compared to that (16.03%) of a pristine device. In addition, a power conversion efficiency (PCE) of 20.01% was achieved using the CsFAMAPbIBr mixed perovskite film and the gamma-ray irradiated SnO₂. The results suggest that systematic low-dose gamma irradiation treatment of ESLs has a synergistic effect of controlling surface properties, enhancing perovskite crystal growth, and controlling oxygen vacancies, and is relatively simple and has high potential as a surface treatment process.

The persistent rise in temperature driven by the emission of greenhouse gases presents a pressing contemporary challenge, fostering innovative cooling techniques. Currently, passive cooling technologies have gained attention in various research fields for their effectiveness in combating heat accumulation. Compared to traditional active cooling methods, which rely on electricity or other energy sources, passive cooling significantly reduces energy consumption and electricity demand. These technologies have demonstrated the potential for temperature reductions of ~1°C–24°C, translating to substantial electricity savings of about 2–300 kWh/year. This paper uses an integrative review approach to highlight the fundamental principles and design strategies underlying passive cooling technologies, such as phase change materials, radiative cooling, and evaporative cooling. Special emphasis is placed on their potential implementation, from preserving biological materials to cooling buildings, electronics, and personal clothing. Passive cooling methods offer cost savings over time due to lower maintenance and operational costs and potentially simpler designs.

The aviation industry is adopting renewable energy sources to reduce greenhouse gas emissions. One of the strong candidates to meet the energy demand of airports with a sustainable way is photovoltaic (PV) systems. This paper systematically assesses the potential risk and energy generation capabilities of installing PV at nine Korean airports. It was found that the risk of PV, particularly concerns about glare and severity of collision accident, is lower than other renewable energy sources. These remaining safety issues of PVs can be mitigated to acceptable levels by maintaining a safe distance from aircraft routes (105 m) and rotating them to face opposite possible routes. The safety management of airport PV ensures to utilize glare-free solar energy harvesting systems throughout the year. Under this safe scenario, the estimated energy generation would be 1.78 ± 0.17 times higher than the energy demand of the airports. Notably, the surplus energy generation by PVs located at smaller airports can offset energy demand of larger international airports. The estimated levelized cost of energy for PVs with acceptable risk is 64.7 ± 0.1 $/MWh, lower than the cost of energy supplied by an external source (103.4 ± 32.7 $/MWh). These findings suggest that PV installations with acceptable risk can significantly contribute to the energy self-sufficiency and sustainability of airports in South Korea.

In the context of severe nuclear accidents, the migration of corium into the reactor pressure vessel (RPV) poses significant hazards, prompting the proposal of the in-vessel melt retention (IVR) strategy, particularly the external reactor vessel cooling (ERVC) approach. Evaluating the accuracy of turbulence models within the melt pool is crucial for assessing the feasibility of IVR. However, previous studies have yet to reach a consensus about the most suitable model due to the lack of data comparison. We aim to conduct a comprehensive comparative analysis of turbulence models to evaluate their performance across a range of Rayleigh numbers, particularly under conditions relevant to IVR scenarios. Therefore, this study employs six commonly used turbulence models in computational fluid dynamics (CFD) software, ANSYS Fluent, to simulate three natural convection experiments (Kulacki–Goldstein, BALI, and LIVE-3D). The results demonstrate that the choice of turbulence model significantly impacts the accuracy of temperature and heat flux predictions within the melt pool. Although the relative temperature deviation is less than 0.1% in all the simulations of the Kulacki–Goldstein experiment, the differences among turbulence models become increasingly pronounced with rising Rayleigh numbers. Among the models tested, wall-modeled large eddy simulation (WMLES) proved the most reliable for complex geometries and high Rayleigh numbers, while the realizable k-epsilon and generalized k-omega (GEKO) models also showed consistent performance. However, the Reynolds stress model (RSM)–baseline (BSL) and detached eddy simulation (DES) models exhibited notable limitations, particularly in scenarios involving solidification and melting. These findings provide valuable guidance for selecting appropriate turbulence models in IVR-related natural convection simulations and highlight the need for further refinement to improve model accuracy across varying melt pool conditions.

Conventional perovskite solar cells (PSCs) have adapted the organic–inorganic hybrid perovskites as the absorption layer due to low processing temperature, superior optoelectronic properties, and simple solution processing. However, hybrid perovskites are more vulnerable to heat compared to inorganic perovskites. For long-term operation, heat stability is essential for the commercialization of PSCs based on hybrid perovskite. In this study, we synthesized inorganic halide perovskite CsPbBr₃ with SiO₂ shell to ensure stability against heat. However, due to the lattice mismatch between the SiO₂ shell and CsPbBr₃, we introduced nickel doping using nickel acetate to reduce this mismatch. The nickel-doped CsPbBr₃–SiO₂ core–shell perovskite exhibited superior thermal stability, maintaining the 92% of its initial performance after 12 h at 353 K.

A neutronics/thermal-hydraulics (TH) coupled spatial dynamics code, reactor system transient analysis-three dimensional (RESTA-3D), has been developed for both static and transient analysis of large advanced light water reactors (LWRs), with a focus on control rod (CR) ejection accidents. The code is based on a neutron diffusion model, employing the widely used “two-step” strategy in 3D Cartesian coordinates. A polynomial nodal expansion method (NEM) is used to handle spatial variables, while the neutron kinetics solver applies the exponential transformation technique. Additionally, the code integrates a single-channel TH module and a steam table set at 15.5 MPa. The accuracy of the code has been validated against three transient benchmarks: the 3D-LRA benchmark for boiling water reactors (BWRs), the NEACRP 3D benchmark, and the mixed oxide (MOX)/UO2 core benchmark for pressurized water reactors (PWRs). These benchmarks address both static and transient behaviors, and the results have been thoroughly analyzed. The close agreement between the RESTA-3D results and reference data, as well as other codes, confirms its reliability, making it a promising tool for future dynamic analyses of large-scale advanced PWRs.

Multistack and multimotor powertrain systems have significant potential for improving the efficiency and performance of fuel cell electric vehicles (FCEVs) compared to conventional powertrain systems. To achieve a superior powertrain system, the major components such as the stack, motor, and transmission of the multistack and multimotor systems should be optimized. To analyze the energy efficiency and dynamic performance of the FCEV, an FCEV analysis model was developed. This model included a two-stack and two-motor powertrain system (2S2M) employing a stack power and motor torque distribution strategy. An optimization problem was formulated with stack transition power, motor torque distribution, and transmission gear ratios as the optimization variables and hydrogen consumption and acceleration time as the objectives for efficiency and performance measures, respectively. An artificial neural network (ANN) model-based optimization method was used to address the computational burden of multiobjective optimization. The optimization results highlighted the Pareto front for the FCEV employing 2S2M, showing a trade-off relationship between the efficiency and performance of the FCEV. Compared to the conventional powertrain system, the 2S2M can reduce hydrogen consumption and acceleration time by up to 7.9% and 6.2%, respectively. An analysis of the distribution of optimal solutions and a comparison of the Pareto fronts for each optimization variable highlighted the necessity for the proposed system optimization method. Furthermore, a comparison between the FCEV and ANN models in terms of computational time for the optimization demonstrated the effectiveness of the ANN model-based multiobjective optimization.