Search Results (17)

The accumulation of ice on power lines severely affects the safety of power systems. Conventional ice melting methods suffer from poor flexibility and adaptability, accompanied by high power consumption. As a novel technical approach, distributed ice melting deploys modular and movable ice melting units at key sections of overhead ground wires, which generate heat on site according to the actual icing conditions of icing segments, and imposes high requirements on the miniaturization of ice melting equipment as well as the regulation strategy of ice melting current. This study proposes a distributed ice melting method for overhead ground wires based on AC power supply, which can adjust the current in accordance with the specific demands of wire protection and ice melting for different line sections. The feasibility and effectiveness of the proposed method are verified through thermodynamic simulations and experimental tests. The de-icing method injects power–frequency AC into the overhead ground wire through a Scott transformer combined with a series capacitor reactive power compensation structure, enabling on-demand regulation by adjusting capacitor switching strategies and transformer operating modes. This approach balances efficiency and flexibility. Based on a reactive power compensation capacity current control strategy and thermodynamic analysis, an electro-thermal-fluid field coupling simulation model for the experimental ground wire was developed. The current regulation strategies for different environmental and operating conditions were calculated and validated. The simulation results show that, under different conditions, the adjustable current effective values of the de-icing system in this model range from 101 to 380 A (line maintenance current), 304 to 622 A (critical de-icing current), and 661 to 1121 A (maximum de-icing current). Field tests demonstrate that this method can stably achieve AC de-icing and current control. For the experimental JLB40-150 model ground wire, adjusting the injected current to 350 A enables safe operation under line maintenance conditions, with a limit not exceeding 400 A. This paper provides a more efficient, flexible, controllable, and widely applicable method for the de-icing of overhead ground wires. Full article

Driven by the demand for miniaturization, high capacitance, and enhanced reliability in high-performance multilayer ceramic capacitors (MLCCs), the continuous thinning of inner electrode layers imposes increasingly stringent requirements on the size, distribution, morphology, and dispersion of nano-nickel powders. We systematically investigate how functional additives regulate the nucleation, growth, and microstructural evolution of nano-nickel synthesized via hydrazine-driven liquid-phase reduction of nickel sulfate. The results demonstrate that the alkanolamine complexing agent (TAC) significantly refines the average particle size and morphology of the nano-nickel through coordination effects. Furthermore, inorganic sulfur salts (ISP), acting via surface adsorption to passivate growth sites and provide catalytic effects, enable a precise and continuous reduction in the average particle diameter from 330 nm down to 60 nm at a mere trace dosage of ~10⁻⁷ mol/L. Regarding dispersion optimization, highly dispersed face-centered cubic (FCC) nano-nickel was successfully prepared by introducing multidentate carboxylate (NNA). High-resolution transmission electron microscopy (HRTEM) was employed to unveil, for the first time, the crystallographic origin of the anomalous surface protrusions typically observed in conventional reaction systems. We confirmed that the family of $\left\{10\overline{1}0\right\}$ crystal planes within these regions, which exhibits interfacial angles of 58.7° and 58.3°, corresponds to a thermodynamically metastable hexagonal close-packed (HCP) nickel phase originating from atomic stacking faults induced by rapid growth kinetics. To address this microstructural defect, a thioether-based amino acid (TAA) was introduced. TAA effectively suppresses the anisotropic growth of the metastable HCP phase through the strong steric hindrance of its long side chains and its selective adsorption onto high-energy facets. Full article

This study evaluates the energy performance of a BOGE C 22-2 oil-injected rotary screw compressor under real industrial conditions. Using direct measurements with a power quality analyzer and thermodynamic modeling, key performance indicators such as compression work, mass flow rate, compressor efficiency, and motor efficiency were determined. The results revealed actual efficiencies of 27–48%, significantly lower than the expected 60–70% for this type of equipment, mainly due to partial-load operation and low airflow demand. A low power factor of approximately 0.72 was also observed, caused by a high share of reactive power consumption. To address these inefficiencies, the study recommends the installation of an automatic capacitor bank to improve power quality and the integration of a secondary variable speed compressor to enhance performance under low-demand conditions. These findings underscore the importance of assessing compressor behavior in real-world environments and implementing techno-economic strategies to increase energy efficiency and reduce industrial electricity consumption. Full article

The authors present an in-depth theoretical study of two nonlinear circuits capable of transient thermal energy harvesting at one temperature. The first circuit has a storage capacitor and diode connected in series. The second circuit has three storage capacitors, and two diodes arranged for full wave rectification. The authors solve both Ito–Langevin and Fokker–Planck equations for both circuits using a large parameter space including capacitance values and diode quality. Surprisingly, using diodes one can harvest thermal energy at a single temperature by charging capacitors. However, this is a transient phenomenon. In equilibrium, the capacitor charge is zero, and this solution alone satisfies the second law of thermodynamics. The authors found that higher quality diodes provide more stored charge and longer lifetimes. Harvesting thermal energy from the ambient environment using diode nonlinearity requires capacitors to be charged but then disconnected from the circuit before they have time to discharge. Full article

The present study examines the relationship between thermal and configurational entropy in two resistors in parallel and in series. The objective is to introduce entropy in electric circuit analysis by considering the impact of system geometry on energy conversion in the circuit. Thermal entropy is derived from thermodynamics, whereas configurational entropy is derived from network modelling. It is observed that the relationship between thermal entropy and configurational entropy varies depending on the configuration of the resistors. In parallel resistors, thermal entropy decreases with configurational entropy, while in series resistors, the opposite is true. The implications of the maximum power transfer theorem and constructal law are discussed. The entropy generation for resistors at different temperatures was evaluated, and it was found that the consideration of resistor configurational entropy change was necessary for consistency. Furthermore, for the sake of generalization, a similar behaviour was observed in time-dependent circuits, either for resistor–capacitor circuits or circuits involving degradation. Full article

Silicides and nitrides of transition metals are expected to play a great role in various applications. They can be both considered as metals and ceramics. Their low resistivity and high melting point make them especially promising for super capacitors technology. Thin bilayer films of Mo and Ti are evaporated on Si substrates with various thicknesses and location with respect to the Si substrate. They are exposed to expanding plasma using (Ar-31%N₂-6%H₂) gas mixtures, which promotes the chemical reactions on the surface of the bilayer films. Because of the intensive diffusion of elements such as Si and Ti, which compete with the diffusion of nitrogen into the surface layers, various thin films of nitrides and silicides form, depending on the location of Mo and Ti films relative to Si substrates. Results are analyzed in light of thermodynamic and kinetic considerations and especially the strong reactivity of Ti towards oxygen and silicium compared with Mo. The large diffusion of Si through Mo–Ti/Si bilayer films prevents the formation of nitrides, whereas a film of Mo, only 50 nm thick, prevents the formation of silicides in Ti–Mo/Si bilayer films, which promotes the formation of TiN from TiO₂ and nitrogen due to the reducing and nitriding effect of plasma. Full article

As the feature size of integrated circuits has been scaled down to 10 nm, the rapid increase in the electrical resistance of copper (Cu) metallization has become a critical issue. To alleviate the resistance increases of Cu lines, co-sputtered CoW and CoB alloying metals were investigated as conductors and barriers in this study. Annealing CoM (M = W or B)/SiO₂/p-Si structures reduced the resistivity of CoM alloys, removed sputtering-deposition-induced damage, and promoted adhesion. Additionally, both annealed CoW/SiO₂ or CoB/SiO₂ structures displayed a negligible V_fb shift from capacitance-voltage measurements under electrical stress, revealing an effective barrier capacity, which is attributed to the formation of MO_x layers at the CoM/SiO₂ interface. Based on the thermodynamics, the B₂O₃ layer tends to form more easily than the WO_x layer. Hence, the annealed CoB/SiO₂/p-Si MIS capacitor had a higher capacitance and a larger breakdown strength did than the annealed CoW/SiO₂/p-Si MIS capacitor. Full article

Electrostatic energy harvesters convert kinetic energy into electrical energy via variable capacitors. Efforts to improve their power output are hampered by a lack of understanding of the fundamental limit for energy conversion efficiency. In heat engines, the theoretical limit of conversion efficiency is intrinsically related to entropy and the second law of thermodynamics. Laying the foundation for similar concepts for kinetic energy harvesters may be necessary for establishing a conversion efficiency limit. Thus, the mixing entropy concept is borrowed from statistical mechanics and is adapted here, for the first time, to characterize the energy transfer between coupled mechanical–electrical oscillators. The investigated system is composed of a spring-mass coupled to an inductance-capacitor circuit via a variable capacitor. Combining the two subsystems (electrical and mechanical) generates entropy, referred to as mixing entropy. A non-dimensional study of the governing equations of the systems and their energy terms is carried out. Trends in mixing entropy are compared with trends in the total energy of the system, assuming a conservative system, weak coupling between electrical and mechanical domains, and identical natural frequency of the two oscillators. It is found that mixing entropy can predict the peak in effectiveness of the energy transfer between the two domains. For the cases studied, the maximum mixing entropy and effectiveness values occur when the ratio of the mechanical domain energy to the total energy of the system is 67%. The maximum effectiveness is independent of the initial conditions and depends on the squared ratio of the natural frequency of the nominal coupling capacitor to the natural frequency of the mechanical system. Full article

FeO is a low-price material with high charge storage capacity, biocompatibility and other characteristics. It has been applied in the fields of catalysts, capacitors, electrodes and composite materials. However, the current method of preparing FeO needs to control the temperature and reducing atmosphere, which increase the production difficulty and cost. In this experiment, the molten salt electrolysis method was used to prepare FeO by using the NaCl-KCl molten salt system and Fe₂O₃ and Al₂O₃ as raw materials, and the influence of temperature on the preparation process was explored. The results showed that the electrolysis process of Fe₂O₃ to FeO is mainly divided into the following three stages: the electric double-layer charging process, Fe₂O₃ to Fe₃O₄ process and Fe₃O₄ to FeO process. The increase in temperature can improve the reaction speed and strengthen the electrolysis effect. The higher the temperature, the less Fe₃O₄ and more FeO in the sample. Through analysis, it was found that the increase in temperature will affect the theoretical voltage of the electrolytic reaction in thermodynamics, resulting in the increase in the overall potential provided by the power supply. In terms of kinetics, the increase in temperature will affect the viscosity of molten salt, so that O²⁻ transport has better kinetic conditions. Full article

In our recent studies, we have developed a thermodynamic biochemical model able to select the resonant frequency of an extremely low frequency electromagnetic field (ELF-EMF) specifically affecting different types of cancer, and we have demonstrated its effects in vitro. In this work, we investigate the cellular response to the ELF electromagnetic wave in three-dimensional (3D) culture models, which mimic the features of tumors in vivo. Cell membrane was modelled as a resistor–capacitor circuit and the specific thermal resonant frequency was calculated and tested on two-dimensional (2D) and three-dimensional (3D) cell cultures of human pancreatic cancer, glioblastoma and breast cancer. Cell proliferation and the transcription of respiratory chain and adenosine triphosphate synthase subunits, as well as uncoupling proteins, were assessed. For the first time, we demonstrate that an ELF-EMF hampers growth and potentiates both the coupled and uncoupled respiration of all analyzed models. Interestingly, the metabolic shift was evident even in the 3D aggregates, making this approach particularly valuable and promising for future application in vivo, in aggressive cancer tissues characterized by resistance to treatments. Full article

The path to the mitigation of global climate change and global carbon dioxide emissions avoidance leads to the large-scale substitution of fossil fuels for the generation of electricity with renewable energy sources. The transition to renewables necessitates the development of large-scale energy storage systems that will satisfy the hourly demand of the consumers. This paper offers an overview of the energy storage systems that are available to assist with the transition to renewable energy. The systems are classified as mechanical (PHS, CAES, flywheels, springs), electromagnetic (capacitors, electric and magnetic fields), electrochemical (batteries, including flow batteries), hydrogen and thermal energy storage systems. Emphasis is placed on the magnitude of energy storage each system is able to achieve, the thermodynamic characteristics, the particular applications the systems are suitable for, the pertinent figures of merit and the energy dissipation during the charging and discharging of the systems. Full article

A new expression for the dielectrophoresis (DEP) force is derived from the electrical work in a charge-cycle model that allows the field-free transition of a single object between the centers of two adjacent cubic volumes in an inhomogeneous field. The charging work for the capacities of the volumes is calculated in the absence and in the presence of the object using the external permittivity and Maxwell-Wagner’s mixing equation, respectively. The model provides additional terms for the Clausius-Mossotti factor, which vanish for the mathematical boundary transition toward zero volume fraction, but which can be interesting for narrow microfluidic systems. The comparison with the classical solution provides a new perspective on the notorious problem of electrostatic modeling of AC electrokinetic effects in lossy media and gives insight into the relationships between active, reactive, and apparent power in DEP force generation. DEP moves more highly polarizable media to locations with a higher field, making a DEP-related increase in the overall polarizability of suspensions intuitive. Calculations of the passage of single objects through a chain of cubic volumes show increased overall effective polarizability in the system for both positive and negative DEP. Therefore, it is proposed that DEP be considered a conditioned polarization mechanism, even if it is slow with respect to the field oscillation. The DEP-induced changes in permittivity and conductivity describe the increase in the overall energy dissipation in the DEP systems consistent with the law of maximum entropy production. Thermodynamics can help explain DEP accumulation of small objects below the limits of Brownian motion. Full article

We experimentally study a piezoelectric energy harvester driven by broadband random vibrations. We show that a linear model, consisting of an underdamped Langevin equation for the dynamics of the tip mass, electromechanically coupled with a capacitor and a load resistor, can accurately describe the experimental data. In particular, the theoretical model allows us to define fluctuating currents and to study the stochastic thermodynamics of the system, with focus on the distribution of the extracted work over different time intervals. Our analytical and numerical analysis of the linear model is succesfully compared to the experiments. Full article

Through the research presented herein, it is quite clear that there are two thermodynamically distinct types (A and B) of energetic processes naturally occurring on Earth. Type A, such as glycolysis and the tricarboxylic acid cycle, apparently follows the second law well; Type B, as exemplified by the thermotrophic function with transmembrane electrostatically localized protons presented here, does not necessarily have to be constrained by the second law, owing to its special asymmetric function. This study now, for the first time, numerically shows that transmembrane electrostatic proton localization (Type-B process) represents a negative entropy event with a local protonic entropy change ($\Delta S_L$) in a range from −95 to −110 J/K∙mol. This explains the relationship between both the local protonic entropy change ($\Delta S_L$) and the mitochondrial environmental temperature (T) and the local protonic Gibbs free energy ($\Delta G_L=T\Delta S_L$) in isothermal environmental heat utilization. The energy efficiency for the utilization of total protonic Gibbs free energy ($\Delta G_T$ including $\Delta G_L=T\Delta S_L$) in driving the synthesis of ATP is estimated to be about 60%, indicating that a significant fraction of the environmental heat energy associated with the thermal motion kinetic energy (k_BT) of transmembrane electrostatically localized protons is locked into the chemical form of energy in ATP molecules. Fundamentally, it is the combination of water as a protonic conductor, and thus the formation of protonic membrane capacitor, with asymmetric structures of mitochondrial membrane and cristae that makes this amazing thermotrophic feature possible. The discovery of energy Type-B processes has inspired an invention (WO 2019/136037 A1) for energy renewal through isothermal environmental heat energy utilization with an asymmetric electron-gated function to generate electricity, which has the potential to power electronic devices forever, including mobile phones and laptops. This invention, as an innovative Type-B mimic, may have many possible industrial applications and is likely to be transformative in energy science and technologies for sustainability on Earth. Full article

The measurement of two-phase cryogenic fluid mixtures flow, also known as slush cryogen flow, with its most attractive form (liquid and solid) is of great interest for various applications, due to its thermodynamic advantages. This paper presents a newly developed device, under the form of a circular capacitor prototype, together with an experimental stand for slush formation. Slush nitrogen was used as testing fluid during the experimental work. Then, the experimental data for slush cryogen flow measurement using the proposed circular shape capacitor were compared with theoretical results obtained by simulation. A three-dimensional flow field model was built and solved for the innovative design slush flowmeter using a computational fluid dynamic (CFD) model. Nitrogen slush density of 874 kg/m³, representing approximately 30% solid fraction, was reported for both the modeling and experimental testing, although the numerical investigation is not limited to these values. By comparing experimental vs. simulation results, a deeper view on the designed configuration can be achieved, thus improving the progress in producing high-performance next generation devices for two-phase flow measurement in terms of physical dimensions, length and space between armatures. Even so, the mathematical model has limitations when mixtures with higher percentages of solid phase and particle sizes are encountered. Full article