International Journal of Energy Research最新文献

This review discusses the history, fundamentals, and applications of different fuel cell technologies, including proton exchange membrane fuel cells (PEMFCs), direct methanol fuel cells, solid oxide fuel cells (SOFCs), phosphoric acid fuel cells (PAFCs), alkaline fuel cells (AFCs), and molten carbonate fuel cells (MCFCs). Recent advances in fuel cell technologies have led to potential applications in aerospace, transportation, and portable and stationary power generation due to high efficiency and low emissions. Fuel cell types are also compared based on efficiency, operating temperature, lifetime, energy/power density, and cost. It was noticed that PEMFCs have the highest mass power density, reaching 1,000 W/kg compared to less than 100 W/kg for SOFCs, which makes them suitable for portable applications such as aircraft. PEMFCs and AFCs are suitable for low-temperature applications and are highly efficient. SOFCs and MCFCs are better for high-temperature operations. SOFCs are robust and suitable for high-power demands, while MCFCs are advantageous for high-power output. Hydrogen fuel cells promise to decarbonize transportation and aviation sectors with the advantages of lower weight, compactness, and quick startup times. However, challenges remain around renewable hydrogen production/infrastructure and aircraft integration, besides hydrogen storage, water management inside fuel cells, and operational robustness under varying pressures. Generally, for all fuel cell types, more focus should be given to enhancing the stability and efficiency of fuel cell materials and reducing their cost.

Studying the hydraulic fracture(HF) propagation behavior of oriented perforation is crucial for optimizing perforation schemes and achieving effective hydraulic fracturing stimulation. In this study, a fully dynamic fluid-mechanical coupling HF propagation model based on the particle flow method was established to investigate oriented perforation hydraulic fracturing. The fracture propagation results obtained by numerical simulations were in good agreement with published experimental results, indicating the reliability of the numerical results. Then, the model was used to study the effects of different perforation and fracturing parameters on the geometrical morphology of the HF under different in situ stresses. The simulation results show that the perforation angle and length have a significant impact on the fracture morphology and redirection of the directional hydraulic fracturing (DHF). As the perforation angle and length increase, the HF will require a longer distance to redirect. The induced compressive stress zones on both sides of the fracture and the tensile stress zone at the tip directly control the reorientation of HFs. The fracturing fluid viscosity and displacement have an important influence on the pore pressure field and induced stress field around the DHF fractures. Under the high perforation angle, the speed of HF redirection slows down with the increase of the fracturing fluid viscosity and displacement. Reducing the seepage effect of fracturing fluid and increasing the displacement is beneficial for controlling the directional propagation of fractures. Choosing reasonable perforation and fracturing parameters can minimize the redirection of fractures.

ZnCl₂ impregnation of the cellulosic precursor is an effective way to generate carbon catalysts with a mesoporous structure and high specific surface area. Herein, we attempt to explore the synthesis of Citrus Limonum Pericarpium (lemon peel), an activated biochar catalyst produced via pyrolysis and consequent sulfonation. The obtained biochar catalyst exhibited notable characteristics, including a high surface area of 863.0 m² g⁻¹ and a substantial sulfur content of 4.02 wt.% (1.25 mmol g⁻¹) by EDX. Following, analytical techniques, such as scanning electron microscopy, BET, X-ray diffraction, Fourier-transform infrared, and TGA, were conducted for a comprehensive analysis of the catalyst. Subsequently, we applied the catalyst to optimize the transesterification process of Jatropha curcas oil (JCO), yielding an impressive 95.2% ± 0.4% yield. The optimization parameters were established with a reaction duration of 60 min, a temperature of 100°C, 8 wt.% catalyst, and JCO: MeOH ratio of 1 : 20. Catalyst reusability was probed over seven subsequent cycles with the final yield observed of over 88.4% ± 0.6%, while the decrease in yield was explained by EDX analysis. In summary, our investigation successfully navigated the synthesis and practical application of a sulfonated porous biochar catalyst for JCO transesterification, achieving noteworthy yields while addressing environmental concerns.

Semiconductor behavior has emerged as a promising substance for numerous advancements in natural energy production, storage, and conversion, as well as in medical technology due to exceptional properties and capabilities of the perovskites. Additionally, this property also presents a great opportunity for solar cells to serve as a substitute for conventional silicon-based photovoltaic systems, as they provide greater efficiency and cost-effective conversion of sunlight to electricity. Here, we are for the first time investigating lead-free environment-friendly cubic perovskites ASnX₃ (A = Na and Li; X = Cl, Br, and I) under different hydrostatic pressures ranging from 0 to 5 GPa. Utilizing the GGA + PBE functional method with a space group of 221 (Pm3m), ASnX₃ compounds (A = Na and Li; X = Cl, Br, and I) demonstrate direct bandgaps at 0 GPa, ranging from 0.790 to 0.282 eV for Li-based halides and 0.760–0.296 eV for Na-based halides, characterizing their semiconductor nature within the perovskite crystal lattice. Furthermore, our analysis revealed that the conduction band and the valence band intersect at a point above the Fermi level which influences the transition of semiconductor to metal or the creation of a half-metallic state. The optical and structural properties of the compound were also examined, and as the pressure rose from 0 to 5 GPa, the absorption redshift occurred. The analysis of magnetic properties revealed that ASnX₃ (A = Na and Li; X = Cl, Br, and I) compounds have diamagnetic behavior in both normal and under pressure conditions. Meanwhile, compounds that satisfy mechanical stability requirements up to certain pressures demonstrate alternations in bulk modulus, shear modulus, and Young’s modulus. The compounds show ductile behavior as their Poisson’s ratio values range between 0.28 and 0.44 for every compound. Increasing pressure increases the values of the compounds, but the compounds remain in the same range of ductile material and show better ductility. Finally, increasing pressure influences the characteristics of the compounds as I-based compounds change phase transitions from semiconductor behavior to metallic behavior. On the other hand, Cl-based and Br-based compounds show semimetallic behavior for increased pressure.

This study systematically optimizes the synthesis parameters for nano-enhanced phase-change materials (NEPCMs) based on paraffin wax and copper oxide. The objective is to collectively improve both thermal conductivity and latent heat capacity. Unlike the previous research, the present approach considers all significant synthesis parameters simultaneously, employing a fractional factorial approach for efficient experimentation. By varying CuO nanoparticle sizes, paraffin wax melting temperatures, and mass fractions of CuO and surfactant in pure paraffin wax, the comprehensive thermal analysis reveals a maximum enhancement of 51.2% thermal conductivity compared to pure paraffin wax. In addition to thermal conductivity improvement, the applied optimization strategy identifies six NEPCM combinations, collectively enhancing thermal conductivity, latent heat of melting, and solidification. Among these, one NEPCM exhibits notable improvements of 13.39%, 6.9%, and 4.5% in thermal conductivity, latent heat of melting, and solidification, respectively, making it suitable for thermal energy storage systems due to combined enhanced thermal properties. Additionally, the ANOVA approach indicates the melting temperature of pure PCM as the most significant factor for thermal conductivity enhancement, with a contribution of 55.45%. The present study has a direct impact on improving thermal properties, specifically in thermal energy storage technology, making it relevant to the thermal management research community.

Efficient wind turbine blade design is crucial, yet current models often fail to fully account for variations in wind inflow due to terrain differences, particularly wind shear. This article aims to verify the theoretical method of designing the geometry of wind turbine blades. The proposed model, which combines the BEM method and the vortex method, was developed to consider the nonuniform inflow caused by wind shear. Model verification employed an explanatory sequential process focusing on two perspectives. First, it examines the correlation between the theoretical terrain roughness coefficient and the blade geometry. Second, it analyzes the relationship between the type of terrain (terrain roughness) and the design of wind turbine blades in two real locations in southeastern Poland. The results highlight the importance of accurate assessment of wind speed and spatial conditions to optimize the use of local wind resources in electricity production. It is suggested that adapting wind turbine blade geometry to the plant’s location will improve resource utilization, providing insight for energy decision-makers. The findings highlight the importance of considering wind shear when designing blades for varying terrain. The methodology is presented on the example of a wind power plant, and at the end of the article, potential directions of future research in this field are outlined.

To evaluate the effectiveness of the wet cavity strategy, the authors developed a stochastic evaluation method that considers the uncertainties of the molten material conditions ejected from reactor pressure vessels. This study analyzed the probability of ex-vessel debris coolability under the wet cavity strategy. The first step was uncertainty analysis using the severe accident analysis code MELCOR to obtain the melt condition. Five uncertainty parameters related to the core degradation and transfer process were chosen. With the assumed probabilistic distributions, the input parameter sets were generated using the Latin hypercube sampling (LHS) method. Analyses were conducted, and the conditions of the melt were obtained. The second step was to analyze the melt behavior in the water and the spreading radius using the JASMINE code and to calculate the height of the debris on the floor. The probabilistic distribution of parameters for the JASMINE analyses was determined from the MELCOR analysis results. LHS generated 200 parameter sets. The depths of the water pool in the analysis were 0.5, 1.0, and 2.0 m. The debris height was compared with the criterion to judge its coolability. Consequently, the probability of successful debris cooling was obtained through the sequence of calculations. The feasibility and technical difficulties in the MELCOR-JASMINE combined analysis were also discussed.

Implementing a rational structure and leveraging unique components are crucial to advancing high-performance supercapacitors (SCs) and essential to unlocking their full potential. Herein, we successfully developed a facile solvothermal synthetic approach for fabricating NiCo-layered double hydroxide (NCLDH) nanosheets for high-performance supercapacitor applications. NCLDH nanosheets were synthesized with precise control over their morphology and size by optimizing the H₂O-to-DMF ratios. Besides, the correlations between the proportion of the solvent and the resulting properties of the NCLDHs were analyzed. The formation of unique vertical orientation nanosheets of interwoven structures was observed in NCLDH-21, where the ratio of H₂O and DMF was 2 : 1. The resulting nanosheets display unique characteristics that distinguish them from other NCLDH materials. The synthesized NCLDH-21 nanostructures had many benefits, including increasing the number of active sites that could be used for redox reactions, facilitating the efficient collection and transport of electrons and ions, and reducing aggregation, which effectively stabilized the volume variation of active matter during cycling. The NCLDH-21 nanosheets were optimized to exhibit a remarkable specific capacitance of 2,054 F g⁻¹ at 1 A g⁻¹ and exceptional rate capability. The assembled hybrid SC (HSC) achieved an impressive energy density of 67.67 Whr kg⁻¹, demonstrating remarkable cycling stability. Hence, the remarkable electrochemical outcomes of NCLDH-21 nanosheets demonstrate their immense potential as a cost-effective electrode material for next-generation energy-storage devices.

This study provides a numerical investigation about J-shaped straight-bladed Darrieus vertical axis wind turbines equipped with outboard, inboard, and two-sided Gurney flap (GF). The performance of the turbines is examined for different GF heights and tip speed ratios (TSRs). The aerodynamic analysis is carried out using power curves, vorticity field, and pressure field surrounding the wind turbine. The results indicate that employing the inboard GF effectively enhances the turbine’s performance by harnessing the drag force in the desired direction and postponing the flow separation up to 14° of azimuth angle. The inboard GF with a height of 0.75% chord length exhibits the best performance among the GFs, showing an increase in output power at higher TSRs up to 12.35%. Conversely, the use of outboard and two-sided GFs of any height cannot improve the turbine efficiency.

The application of surface-active agents during oil recovery process is ubiquitous. It is essential to achieve a satisfying oil recovery rate with low dosage of surface-active substances in an environment-friendly manner. Despite the wide application of surface-active agents, the impact of individual and the combination of surface-active agents on the microscale multiphase flow and interfacial phenomenon have not been systematically investigated. In this work, idealized pore-throat network micromodels were employed as the surrogate of the porous media to study the influence of surface-active agents on the oil recovery involving nonionic, anionic, zwitterionic surfactants, and nanoparticles. Oil recovery efficiency and residual oil characteristic in different permeable regions were quantitatively analyzed. Anionic surfactants resulted in the highest oil recovery of 79% and were selected to formulate composite agents. The combination of anionic and zwitterionic surfactants resulted in better overall oil recovery which was up to 84%, yet complicated interfacial phenomenon was observed. To comprehend the complex interactions between crude oil and assorted surface-active agents, the impact of interfacial tension, wettability, and emulsification on oil-brine flow behaviors and final oil recovery was discussed providing an insight on the efficient and cost-effective application of surface-active agents on enhancing oil recovery.