Energy technology最新文献

Liquid piston compressors gain attention due to their potential for more efficient and isothermal compression compared to traditional solid piston compressors. Liquid piston compressors use a liquid column instead of a solid piston, allowing for innovative mechanisms to enhance heat transfer and achieve near-isothermal compression. However, a validated analytical model for heat transfer in liquid piston compressors is still needed to understand the exhaust phase within a liquid piston. In this work, a thermal network model, able to predict the polytropic index to within 8% of the experimental results, is proposed. Moreover, thorough experimentation is conducted to measure the amount of liquid carried over to better understand the exhaust phase. In the results, it is revealed that the piston carries over 13–21 mL of liquid within the exhaust gas for 10–23 s of stroke. Notably, the difference in liquid carried over for the three-stroke times is not statistically significant, indicating that the liquid carried over is a function of liquid piston design and not stroke time. Finally, most liquid piston applications consider only water; hence, for the first time, this research assesses the stability of a cycle using a nonflammable hydraulic fluid (Fuchs 46 M red) to enhance compressor longevity and material compatibility.

This study introduces a new symmetrical hydraulic piezoelectric energy harvester. By integrating theoretical analysis, simulation, and empirical testing, the research delves into the energy-harvesting potential of monolithic single-side output, monolithic two-side parallel-connected output, stacked one-side parallel-connected output, and stacked two-side parallel-connected output under varying parameter configurations. Additionally, it elucidates the energy dissipation occurring during the energy-harvesting process of stacked piezoelectric disks. It has been observed that the primary determinant of voltage is the amplitude of pulsation, not the static pressure. Concurrently, the study also addresses the consistency of power generation between multiple channels. A study is made on whether there is a proportional relationship between single-channel power generation and multi-channel power generation. The root mean square (RMS) voltage of each connection sharply rises with resistance from 2 to 100 KΩ. It is found that the performance of parallel connection of monolithic piezoelectric disk is better than that of other connection methods. At 3 MPa and 100 Hz, the optimal resistance is 16 KΩ, yielding a maximum average power of 1155.63 μW and an optimal power density of 1.774 μW (bar mm³)⁻¹. Consequently, the research offers a novel approach to addressing the issue of sustainable energy supply for low-power electronic devices and sensors.

In electric vehicle industry, rechargeable multicell battery packs commonly with fixed configurations are adopted. Such fixed battery configurations have several drawbacks, including limited fault tolerance during unusual operating situations, poor cell state variation management, etc. Thus, this article proposes a self-reconfigurable battery pack design considering two scenarios: with and without active cell balancing. Herein, the issue of cell state variation is mostly solved by the proposed configuration mode, and further monitoring, control, and protection can be easily appended to accomplish other functionalities, for example, meeting dynamic voltage requirement. Each proposed design is validated by simulation results for a six-cell polymer lithium-ion battery pack. The proposed design can maximally utilize the battery's capacity and help to protect cells from over-charging and over-discharging as well. This research could be further extended to other application scenarios involving wide-range dynamic voltage requirements.

The study explores carbazole-based organic molecules as transport layers in durable perovskite solar cells, focusing on their optoelectronic and charge transfer properties. Thirteen carbazole derivatives are systematically analyzed via density functional theory (DFT) calculations to understand their structure and optoelectronic characteristics. Substituents like bromo, phenyl, thiophenyl, and pyridyl at positions 3,6- and 2,7- of carbazole were studied. Phenyl and thiophenyl substitutions lowered highest occupied molecular orbital (HOMO) energy levels, while bromo and pyridyl increased them, tuning HOMO energies from −5.45 to −6.03 eV. These energies align well with perovskite materials valence bands, with absorbance primarily below 400 nm, complementing perovskite absorption. The compounds showed high light-harvesting efficiencies (LHEs) (0.22 to 0.94) and improved radiative lifetimes. Theoretical investigations identified most compounds as effective p-type hole-transport materials (HTM), except 3,6- and 2,7-dithiophenyl carbazoles, which exhibited n-type behavior due to low hole reorganization energies. Overall, the study highlights computational design's role in developing carbazole derivatives as promising charge carrier precursors for perovskite solar cells.

The catalytic activity of metal catalyst is closely related to its particle size. Yet, the size effect in electrocatalytic oxygen reduction reaction (ORR), an important reaction for metal-air batteries and fuel cells, has not been clearly studied. Herein, a two-step anchoring method is utilized to control the Fe catalyst in forms of nanoparticles (NPs), ultrasmall nanoclusters (NCTs), and isolated atoms as well as stabilized and dispersed by carbon polyhedrons interconnected with carbon nanotubes (CNTs). The uniformly distributed Fe NCTs displays superior ORR performance compared with Fe NPs, isolated Fe atoms, and commercial Pt/C. The brilliant ORR activity of Fe NCTs is a result of its unique electron structure and abundant edge and corner active sites. Due to the porous structure of carbon polyhedrons and high electron conductivity of CNTs, Fe NCTs also delivers an excellent discharge performance in zinc-air battery with a peak power density of 213.3 mW cm⁻² and long-term stability. In these findings, a new strategy for the design of metal NCTs catalysts applied in various catalytic reactions is opened up.

On-line hydrogen production via methanol steam reforming (MSR) has gained considerable interest due to its high efficiency, affordability, and eco-friendliness. Currently, this technology has been widely applied in the industry and has become an important method for hydrogen energy production. However, there are still some issues with this technology, such as short catalyst lifespan and CO pollution, which require further research and improvement. This article provides a comprehensive review of the research progress made in this field, with a particular focus on the catalyst development, reaction mechanism, theoretical calculation, and reactor design. Additionally, the challenges and prospects of on-line hydrogen production by MSR are also discussed. In conclusion, MSR technology for hydrogen production has vast application prospects and development potential. It will be further explored in-depth and extensively in future research.

Recent research suggests that the implementation of more efficient combined cooling and power systems, which enable the cogeneration of electricity and cooling, can enhance the efficiency of hybrid plants. The present investigation is motivated by finding that, in the literature review on combined power and cooling systems, there is very limited information on the coupling of the organic Rankine cycle (ORC) and the ejector refrigeration cycle (ERC) with low sink temperatures. A suggested approach to do this involves using hot exhaust gas and waste heat engines to power an ORC hybrid system. To enhance the ORC–ERC system's performance, three heater configurations use waste heat from the ORC turbine exhaust, ejector, and engine waste heat to heat the working fluid. Renewable energy sources are the primary focus of most current research initiatives. The present research focuses on unique ORC and ERC systems, considered as combined power and cooling systems, with the goal of improving exergy performance at low temperatures. The suggested ORC–ERC can generate energy destruction of 69.85 kW at a source temperature of 155 °C, with an exergetic efficiency of 76.9% at the turbine. Setting the entrainment ratio at 0.5 results in a total sum unit cost of products (SUCP) of 465 $/kW-h for the ORC–ERC. Furthermore, the 37.83% exergy destruction ratio introduces heat exchanger 2 (HE2) as the primary cause of the suggested ORC–ERC's irreversibility. A detailed parametric study reveals that altering the hot source temperature and entrainment ratio improves the system's SUCP. The current examination at high sink temperatures may be expanded to an advanced exergoenvironmental investigation.

The development of low-cost, high-performance electrocatalysts for the oxygen evolution reaction (OER) is essential for a vast array of chemical and energy transformation applications. Using non-platinum metals as electrocatalysts in a key process such as OER has become increasingly attractive given their relatively low cost, high electrocatalytic activity, and low environmental impact. Herein, to achieve a better catalytic material with high permeability and mass charge transfer in a catalytic framework, a novel, oxygen-defective Sm₂O₃/CuO nanohybrid with nanocuboid architecture is developed. The creation of a new composite material which consist of samarium oxide and copper oxide, demonstrates high effectiveness in the process of electrochemical water splitting. The combined use of samarium oxide and copper oxide improves the electrocatalytic performance, stability, and durability due to it synergistic effect. In alkaline media, the Sm₂O₃/CuO nanocomposite exhibits an astonishing overpotential of 248 mV along with a lower Tafel value of 46 mVdec⁻¹ for OER and nanocomposite also exhibits acceptable hydrogen evolution reaction (HER) performance. Due to the unprecedented porous nanocuboid morphology and the strong synergistic effect between the two materials, the oxygen-defective Sm₂O₃/CuO composite exhibits impressive electrical properties and performs exceptionally well as an electrocatalyst for intrinsic water splitting. At an operational potential of 0.5 V, porous Sm₂O₃/CuO displays outstanding reactivity, Sm₂O₃/CuO exhibits remarkable results during electrochemical operation.

Defect-type carbon, doped with nitrogen and oxygen, is synthesized using the high-temperature solid-phase method. X-ray photoelectron spectroscopy analysis reveals the presence of nitrogen, including pyridine nitrogen, pyrrole nitrogen, and graphitized nitrogen, incorporated into the carbon structure. Additionally, oxygen is introduced into carbon, with both CO and CO functionalities are observed. Transmission electron microscopy and scanning electron microscopy indicate that all samples exhibit a morphology of carbon microblocks with localized turbocharged lattice regions. Electrochemical tests demonstrate that the nitrogen- and oxygen-doped carbon microblocks exhibit excellent cycling performance and high rate capacity. Specifically, at current densities of 1 and 2 A g⁻¹, the rate capacity remains at 385.6 and 214.4 mA h g⁻¹, respectively. Furthermore, the discharge capacity at 5 A g⁻¹ remains at 58.3 mA h g⁻¹ on the 3500th cycle. The defects introduced by nitrogen and oxygen doping not only enhance reactivity and electronic conductivity but also improve lithium-ion diffusion dynamics.