Electrical Energy Input Research Articles

Hydrodynamic Characteristics of a High-Voltage ElectroChemical Explosion with Controlled Input of Electrical Energy into the Discharge Channel

Hydrodynamic Characteristics of a High-Voltage ElectroChemical Explosion with Controlled Input of Electrical Energy into the Discharge Channel

Study on the Prediction of Launcher Efficiency of Electromagnetic Launcher Based on Particle Swarm Optimization-Improved BP Neural Network

Launcher efficiency is an important index for evaluating the performance of the electromagnetic launcher, and it reflects the ability of the launcher to convert input electrical energy into kinetic energy of the armature. In this paper, the launcher efficiency is taken as the objective function of bore parameter optimization, and particle swarm optimization is used to optimize the initial parameters of the BP neural network to improve the accuracy of the neural network in predicting launcher efficiency. The results show the following: (1) The predicted efficiency of the launcher shows the same trend as the experimental results. When the ratio of rail separation and rail height is greater than 1.75, the rate of change in the launcher efficiency curve decreases as the rail separation increases. (2) The weight of the influence of each parameter on the launcher efficiency follows the following law: convex arc height > rail separation > rail height > rail thickness. (3) The mean absolute error of the BP neural network prediction is 0.70%; after optimization by PSO, the mean absolute error is reduced to 0.28% and the mean relative accuracy is improved from 0.9774 to 0.9910, which indicates the feasibility of the PSO-BP neural network for the prediction of the launcher efficiency of an electromagnetic launcher.

Integrating microbial electrochemical cell in anaerobic digestion of vegetable wastes to enhance biogas production

Anaerobic digestion is a highly promising approach to manage agricultural/food wastes that reduces pollution and produces energy effectively. In this study, we investigate the incorporation of a microbial electrolysis cell (MEC) in anaerobic digestion process with the introduction of two graphite felts to enhance biogas production with minimal electrical energy input. The high amount of biogas (1890 ± 113.1 mL) was produced from the 1:2 v/v mixture of vegetable wastes in water and 0.8 V supplemented at 27 °C. Biogas could also be effectively produced in MEC at 18 °C (632 ± 14.8 mL), which is more than double in comparison with biogas produced without voltage (303 ± 27.5 mL). Maximum COD reduction was found in MEC (70.84 ± 5.54 %) than in control (20.35 ± 4.53 %). Three Bacillus strains and one Exiguobacterium strain were isolated from the MEC sludge. Electricity supplemented anaerobic digestion can produce higher amount of biogas and improve waste degradation by transforming waste into energy.

Electric-field assisted cascade reactions to create alginate/carboxymethyl chitosan composite hydrogels with gradient architecture and reconfigurable mechanical properties

Rational designs of polysaccharide-based hydrogels with organ-like three-dimensional architecture provide a great possibility for addressing the shortages of allograft tissues and organs. However, spatial-temporal control over structure in bulk hydrogel and acquire satisfied mechanical properties remain an intrinsic challenge to achieve. Here, we show how electric-field assisted molecular self-assembly can be coupled to a directional reaction-diffusion (RD) process to produce macroscopic hydrogel in a controllable manner. The electrical energy input was not only to generate complex molecule gradients and initiate the molecular self-assembly, but also to guide/facilitate the RD processes for the gel rapid growth via a cascade construction interaction. The hydrogel mechanical properties can be tuned and enhanced by using an interpenetrating biopolymer network and multiple ionic crosslinkers, leading to a wide-range of mechanical modulus to match with biological organs or tissues. We demonstrate diverse 3D macroscopic hydrogels can be easily prepared via field-assisted directional reaction-diffusion and specific joint interactions. The humility-triggered dissipation of functional gradients and antibacterial performance confirm that the hydrogels can serve as an optically variable soft device for wound management. Therefore, this work provides a general approach toward the rational fabrication of soft hydrogels with controlled architectures and functionality for advanced biomedical systems.

Monitoring the Dynamics of the Galvanic Replacement Reaction to Develop Free-Standing Electrocatalysts

Hydrogen (H2) is well-known for its potential to become the future fuel and bring a more sustainable energy system [1]. The selective electrooxidation of organic compounds from biomass appears to be a possible substitute for the kinetically slow oxygen evolution reaction (OER) at the anode, which increases the electrical energy input for a conventional water electrolysis in alkaline media [2]. However, this approach is currently impeded by limited fundamental knowledge of the different active sites of electrocatalysts. The latter can be used to control selectivity at low potential and high current density to co-generate value-added products at the anode instead of CO2 by complete oxidation. Nanostructured gold-based multi-metal electrocatalysts can meet such objectives. Particularly in the electro-valorization of cellulosic biomass at electrode potentials unfavorable to C-C bond breaking and high overall cell voltage.To develop such electrocatalysts, we have initiated a multivariate methodology to study the dynamics of galvanic replacement between silver and gold. This procedure allows us to control nanoporosity and nanoalloying in the resulting gas diffusion electrode (GDE): GDE-Ag1-xAux. GDE-Ag represents the electrode upon which Ag particles were electrochemically grown prior to reaction with Au(III). Thermodynamically, silver with E°(Ag+/Ag) = 0.8 V vs SHE (standard hydrogen electrode) can be replaced by gold with E°(AuCl4 –/Au) = 1.0 V vs SHE according to: 3Ag + xKAuCl4(aq) → 3xAgCl + xKCl + Ag3-3xAux.[2,3] From a kinetic point of view, the challenge is to capture in real time the formation of metal cages of Ag-Au alloys after a '3by1' atomic exchange that introduces nanoporosity and electronic strain as silver and gold have a similar atomic radius. To interrogate the driving force behind this redox process, we have also established an electrochemical methodology to extract quantitative data, allowing detailed capture of the mixed electrochemical and mass transport (diffusion) kinetics. As the precipitation product AgCl leads to pore fouling, we have developed an efficient methodology to trigger its instant dissolution as soon as it is formed, thus promoting the production of a high-quality alloy. As shown in Figure 1, upon injection of a KAuCl4 solution into a degassed solution in contact with the GDE-Ag electrode, the open circuit potential (OCP) begins to change. This evolution is due to the modification of the electrochemical interface as silver atoms are progressively replaced by gold atoms. Thereby, leading to a regulated potential defined either by the Ag(I)/Ag redox couple, or by the Au(III)/Au pair. Interestingly, we found that the OCP variation logically depends on initial conditions such as Ag loading on the GDE, KAuCl4 concentration, Ag particle size, etc. This fundamental knowledge has led to the synthesis of efficient electrocatalysts for the oxidation of cellulose subunits in alkaline media with an onset electrode potential much lower than OER (E < 1 V vs RHE (reversible hydrogen electrode)). Indeed, the formation of an alloy phase, the creation of nanoporosity within it and the free-standing nature amplify, through synergistic and electronic effects, the electrocatalytic efficiency. Acknowledgments This work was funded by French National Research Agency (ANR-22-CE43-0004).

Dynamic-based artificial intelligence model for simulation and optimization of the single chamber anode brush microbial electrolysis cell

Microbial electrolysis cells (MECs) have become more attractive because they can produce hydrogen (H2) from various organic sources with a low input electrical energy requirement. In this study, a dynamic model for the single-chamber anode brush MEC with acetic acid as a carbon source was developed for the first time. The dynamic model was calibrated and validated using both experimental and literature data, with a high coefficient of determination (R2) of 0.87–0.99, a high Pearson correlation coefficient (PCC) of 0.93–0.99, and a low normalized root mean squared error (NRMSE) of 0.221–0.078. For rapid simulation and optimization, the validated dynamic model was reproduced using an artificial neural network (ANN), and particle swarm optimization (PSO) was then applied to optimize the fitness functions derived from this ANN model (i.e., hydrogen production yield, hydrogen production rate, hydrogen fraction in biogas, and total energy recovery). As a result, the proposed method took about 3 s with an absolute error of <3.5 %. The optimization results revealed that an optimal condition (including applied voltage, operating temperature, substrate concentration, and reactor working volume) cannot exist to obtain the maximum values of all performance parameters simultaneously. Under the same importance, the co-optimal condition was determined at an applied voltage of 0.9 V, temperature of 36.2 °C, substrate concentration of 0.87 g/L, and reactor working volume of 0.05 L. At such co-optimal conditions, MEC achieved an H2 yield of 1168.6 ± 13.3 mL/g with a production rate of 185.6 ± 2.7 mL/L/h, an H2 fraction of 63.6 ± 0.2 %, and a total energy recovery (including electrical, substrate, heat, and mixing input energies) of 16.7 ± 0.2 %. Although these performances increased 1.5–2.3 times compared to non-optimal conditions, the low energy efficiency indicates the need for further investigation into combining MEC with sustainable energy sources, such as solar, wind and osmosis.

Enhancing dewaterability of water resource recovery facility solids with electrochemical treatment through synergetic effects of acidification and cation removal

Solids dewaterability is vital for water resource recovery facilities to effectively manage and dispose treatment residuals, and current methods for improving dewaterability is at the expense of chemical consumption. Herein, an electrochemical approach that integrates anodic acidification, electrooxidation, and cation removal was investigated to enhance solids dewaterability. The results show that the specific resistance to filtration (SRF) was decreased by > 97 % for raw solids before anaerobic digestion, anaerobically digested solids (ADS), and primary solids. ADS exhibited the highest conductivity and required the least energy (34.9 ± 1.3 kWh m−3 treated solids). Increasing the applied current density reduced treatment time but demanded greater energy consumption. Both acidification and cation removal were critical to dewaterability enhancement: acidification facilitated the flocculation of solids flocs through protonation of functional groups and the leaching of divalent ions, while cation removal reduced competition for proton binding, leading to improved dewaterability. The input of electrical energy for the electrochemical treatment can potentially be offset by revenue from recovered nutrient products and use of renewable energy. This study has demonstrated the feasibility of using electrochemical processes for solids treatment and resource recovery.

Energy transfer, conversion and mechanical regulation in graded piezoelectric semiconductor bipolar junction transistor

While the effective regulation of carrier redistribution in piezoelectric semiconductor devices by mechanical loads through piezoelectric polarized electric fields is well-studied, there is a scarcity of reported research on the influence of energy transfer and conversion characteristics in a non-thermal equilibrium state of these devices. This paper establishes a nonlinear multi-field coupling model for piezoelectric semiconductor graded bipolar junction transistor (PS-GBJT) and proposes a corresponding multi-gradient iterative algorithm. We regard the product of current and built-in electric field as the work done by electric field force on carriers. By incorporating the energy absorbed/released during carrier recombination/generation process, we observe that non-equilibrium carriers act as a medium that facilitates energy conversion between these two mechanisms. Additionally, the non-uniformly distributed doping extends the influence of space charge region throughout entire transistor. In terms of external input electrical energy, the emitter, base, and collector regions play roles of input energy, transfer energy, and output energy, respectively. The study concludes by demonstrating the regulation of energy transfer or conversion efficiency in emitter, base, and collector regions through mechanical loads, thereby altering the heating behavior of entire GBJT and reshaping its energy transfer path. This leads to the significant finding that distinct energy transfer paths fundamentally define the various operational states of GBJT. The novel insights gained from this research hold reference value for thermal design and energy management of electronic devices.

Self-Organizing Sub-μm Surface Structures Stimulated by Microplasma Generated Reactive Species and Short-Pulsed Laser Irradiation.

Catalysts are critical components for chemical reactions in industrial applications. They are able to optimize selectivity, efficiency, and reaction rates, thus enabling more environmentally friendly processes. This work presents a novel approach to catalyst functionalization for the CO2 reduction reaction by combining the reactive species of an atmospheric pressure plasma jet with the electric fields and energy input of a laser. This leads to both a nanoscale structuring as well as a controllable chemical composition of the surface, which are important parameters for optimizing catalyst performance. The treatment is conducted on thin copper layers deposited by high power pulsed magnetron sputtering on silicon wafers. Because atomic oxygen plays a key role in oxidizing copper, two photon absorption fluorescence is used to investigate the atomic oxygen density in the interaction zone of the COST plasma jet and a copper surface. The used atmospheric pressure plasma jet provides an atomic oxygen density at the surface in a distance of 8 mm to the jet nozzle of approximately or a flux of . Pulsed laser-induced dewetting is used to form nanoparticles from the deposited copper layer to enhance catalytic performance. Varying the layer thickness allows control of the size of the particles. A gas flow directed on the sample during the combined treatment disturbs the particle formation. This can be prevented by increasing the laser energy to compensate for the cooling effect of the gas flow. Investigating the surface using X-ray photoemission spectroscopy reveals that the untreated copper layer surface consists mostly of metallic copper and Cu(I) oxide. Irradiating the sample only with the laser did not change the composition. The combination of plasma and laser treatment is able to produce Cu(II) species such as CuO, whose concentration increases with treatment time. The presented process allows the tuning of the ratio of C2O/CuO, which is an interesting parameter for further studies on copper catalyst performance.

Enhancement of Biogas (Methane) Production from Cow Dung Using a Microbial Electrochemical Cell and Molecular Characterization of Isolated Methanogenic Bacteria

Biogas has long been used as a household cooking fuel in many tropical counties, and it has the potential to be a significant energy source beyond household cooking fuel. In this study, we describe the use of low electrical energy input in an anaerobic digestion process using a microbial electrochemical cell (MEC) to promote methane content in biogas at 18, 28, and 37 °C. Although the maximum amount of biogas production was at 37 °C (25 cm3), biogas could be effectively produced at lower temperatures, i.e., 18 (13 cm3) and 28 °C (19 cm3), with an external 2 V power input. The biogas production of 13 cm3 obtained at 18 °C was ~65-fold higher than the biogas produced without an external power supply (0.2 cm3). This was further enhanced by 23% using carbon-nanotubes-treated (CNT) graphite electrodes. This suggests that the MEC can be operated at as low as 18 °C and still produce significant amounts of biogas. The share of CH4 in biogas produced in the controls was 30%, whereas the biogas produced in an MEC had 80% CH4. The MEC effectively reduced COD to 42%, whereas it consumed 98% of reducing sugars. Accordingly, it is a suitable method for waste/manure treatment. Molecular characterization using 16s rRNA sequencing confirmed the presence of methanogenic bacteria, viz., Serratia liquefaciens and Zoballella taiwanensis, in the inoculum used for the fermentation. Consistent with recent studies, we believe that electromethanogenesis will play a significant role in the production of value-added products and improve the management of waste by converting it to energy.

Life Cycle Assessment as a Decision-Making Tool for Photochemical Treatment of Iprodione Fungicide from Wastewater

Water contamination with various micropollutants is a serious environmental concern since this group of chemicals cannot always be removed efficiently with advanced treatment methods. Therefore, alternative chemical- and energy-intensive oxidation processes have been proposed for the removal of refractory and/or toxic chemicals. However, similar treatment performances might result in different environmental impacts. Environmental impacts can be determined by adopting a life cycle assessment methodology. In this context, lab-scale experimental data related to 100% iprodione (a hydantoin fungicide/nematicide selected as the model micropollutant at a concentration of 2 mg/L) removal from simulated tertiary treated urban wastewater (dissolved organic carbon content = 10 mg/L) with UV-C-activated persulfate treatment were studied in terms of environmental impacts generated during photochemical treatment through the application of a life cycle assessment procedure. Standard guidelines were followed in this procedure. Iprodione removal was achieved at varying persulfate concentrations and UV-C doses; however, an “optimum” treatment condition (0.03 mM persulfate, 0.5 W/L UV-C) was experimentally established for kinetically acceptable, 100% iprodione removal in distilled water and adopted to treat iprodione in simulated tertiary treated wastewater (total dissolved organic carbon of iprodione + tertiary wastewater = 11.2 mg/L). The study findings indicated that energy input was the major contributor to all the environmental impact categories, namely global warming, abiotic depletion (fossil and elements), acidification, eutrophication, freshwater aquatic ecotoxicity, human toxicity, ozone depletion, photochemical ozone creation, and terrestrial ecotoxicity potentials. According to the life cycle assessment results, a concentration of 21.42 mg/L persulfate and an electrical energy input of 1.787 kWh/m3 (Wh/L) UV-C light yielded the lowest undesired environmental impacts among the examined photochemical treatment conditions.

Combined control of PM and NOx emissions by corona discharge

This work investigates the potential of corona discharge to control particulate matter and NOx emissions from small-scale biomass combustion. The electrostatic precipitator (ESP) was designed and used to suppress emissions from a 15-kW heating unit. The ESP was operated at different power modes at both polarities and demonstrated the capability to reduce NOx emissions with a removal efficiency of 78 % while PM concentration was reduced to a magnitude of particle content in ambient air. The efficiency of ESP was evaluated considering the technological parameters, namely the reduced electric field, Nt-product, and specific input energy. The growth in NOx abatement was observed when the energy input exceeded 1 J/L for both polarities and Nt-product exceeded 4.5 × 108 s/cm3/1 × 109 s/cm3 for negative/positive corona. The results of this work may contribute to understanding the processes in corona discharge and optimising corona discharge systems for various applications.

Unique production strategy of Pt/C electrocatalysts via pulsed laser for hydrogen generation: Insights screening by DFT calculations

Design and optimizing the components and structure of highly-active electrocatalysts is a prevalent approach for reducing the input electrical energy consumption and concurrently H2 fuel production. An efficient and sustainable method is a water-electrolyzer for H2 generation, but still restricted by the stable electrode materials. In this study, a green chemistry approach for one-pot production of Pt/C nanospherical with controllable ratios of Pt and C was demonstrated using simple pulsed laser ablation in liquid (PLAL) process, during which Pt target ablation in diverse solvents (water, methanol, ethanol, and 1-propanol) without external carbon source and reducing/capping agents. The carbon-rich solvents are acted as both C-source and solvent, which are decomposed during the PLAL process, producing C, H, and OH ions inside the cavitation bubble which condenses as C-shells on the Pt surface. The optimal Pt/C proportions have the highest electrochemical H2-evolution in acidic media with an overpotential of 59 mV at 10 mA/cm2, Tafel slope of 41 mV/dec, and j0 of 0.686 mA/cm2. The exceptional electrocatalytic concert of optimal Pt/C was further supported by the density functional theory. Optimized C-content in Pt/C reveals good dispersion and strong interaction of C with Pt can make efficient electron transfer, structural stability, and electrochemical durability, resulting in superior electrocatalytic performance in electrolyzer devices.

Current rate flash sintering of nickel at ambient temperature in &lt;1 min

AbstractWe show that powder pressed specimens of nickel can be sintered to 99.96% density by injecting electrical current, without the use of a furnace. Full sintering could be accomplished in 10 to 52 s by changing the current rate from 5 to 1 A/s. In all instances, the samples sintered abruptly at a current density of ∼20 A mm−2. The grain size of the sintered samples was somewhat larger than the nickel powder particle size (∼60 μm vs. 40 μm). Tensile testing yielded a yield strength of 98 MPa, ultimate tensile stress of 323 MPa, and ductility of ∼17%. Four in‐operando measurements are reported: (i) sintering, (ii) the change in resistance with current density, (iii) the temperature, and (iv) electroluminescence. The change in resistance during flash sintering exhibited a high peak followed by a steep decline in resistance; the transient is attributed to the breakdown of particle–particle interface resistance. The same cycle repeated with the flash‐sintered, dense sample, did not show the spike, and gave reproducible results. The resistance data for these latter cycles, when viewed as a function of temperature exhibited sigmoidal behavior: initially lower, and then higher than the literature values. This unusual behavior reflects the influence of defects generated during flash. We have also measured the endothermic enthalpy, expressed by the difference between the in situ input electrical energy and the radiation, convection, and specific heat losses. Dividing by the formation energy of Frenkel pairs yields the concentration of defects, estimated to be 0.3–0.4 mol %. These concentrations are far above thermal equilibrium; it is concluded that flash of metals is a far from equilibrium phenomenon.

Effects of ignition voltage and electrode structure on electric ignition and combustion characteristics of Ammonium Dinitramide (ADN)-based liquid propellants in electric ignition mode in inert gas environment

Hydrazine is toxic and carcinogenic, which greatly increases the difficulty of application and no longer meets the needs of green aerospace. As a green propellant, the Ammonium Dinitramide (ADN)-based liquid propellant has the advantages of higher specific impulse, being non-toxic, pollution-free, and easy storage. However, an ADN-based space engine in orbit has exposed the problems of high-temperature deactivation of catalysts and cold-start failure. An active ignition technology—electric ignition technology was explored in this paper to break through the technical bottleneck of catalyst deactivation and the inability to a cold start. An experimental system of a constant-volume combustor for the ADN-based liquid propellant based on the electric ignition method was established. The electric ignition and combustion characteristics of the ADN-based liquid propellant in a volume combustor with an electric ignition method were studied. The influencing mechanisms of the ignition voltage and the electrode structure on the electric ignition characteristics of the ADN-based liquid propellant were investigated. An elevation of the ignition voltage could facilitate the ignition process of the ADN-based liquid propellant, curtail electric energy input and heating effect, while exerting an adverse impact on the combustion process of the propellant. An increase in the ignition voltage enhanced the ignition process of the propellant while simultaneously suppressing its combustion process when utilizing mesh electrodes. Compared to the strip electrodes, the mesh electrodes increased the contact area between the electrodes and the propellant, increased the electric energy input power in the electric ignition process, and reduced the ignition delay time. The mesh electrodes could promote the combustion process of the propellant to a certain extent.

Electrical microparticle acceleration by high-speed membrane deformation

In this study, we conducted experiments to explore the potential of a low-power exploding foil initiator for accelerating microparticles through high-speed membrane deformation. This involved the use of a conductive layer with a conversion section known as a “bridge,” which was positioned between the substrate and the cover layer. The application of pulsed electrical energy led to Joule heating at the bridge, while the vaporized gas generated impulsive loading, resulting in the deformation of the cover layer. According to the principles of energy conservation, 8.7% of the electrical input energy was converted into kinetic energy for the membrane. This deformation process achieved a velocity of 800 m/s, with a corresponding strain rate of 1.6 × 107 s−1. The applied impulse predominantly induced extension stresses in the cover layer rather than bending stresses. Under these conditions, a 17.5-µm radius polylactic acid bead was propelled and subsequently captured by a silicone gel layer, resembling human dermic skin. Considering factors such as particle clustering and deceleration due to air resistance during supersonic flight, assuming a normal incident angle, it was estimated that approximately half of the ejected particles could reach the human dermic layer, located 200 µm beneath the skin surface. These findings suggest that pulse discharge is a promising method for inducing high-speed membrane deformation, and the electrical microparticle accelerator holds potential for applications in needle-free drug delivery.

Li–Pd–Rh-D2O electrochemistry experiments at elevated voltage

In 2013, the U.S. Navy disclosed an electrochemistry procedure intended to produce MeV-energy nuclear particles, based on eV-energy electrical inputs, which may be indicative of a new scientific phenomenon. This work is based on the 2013 disclosure and shows initial evidence validating the prior claims of nuclear particle generation. Additionally, several variations on the 2013 electrochemical recipe are made in order to find a highly repeatable recipe for future replications by other teams. The experiments described here produced dense collections of tracks in solid-state nuclear track detectors, radio frequency (RF) emissions, and anomalous heat flux, which are indicative of potential nuclear, or unusual chemical, reactions. Experimental results include tracks in solid-state nuclear track detectors similar in size to tracks produced by 4.7 MeV alpha particles on identical detectors exposed to radioactive Th-230; RF pulses up to 6 dB above the noise floor, which indicate that these signals were likely not background noise and not caused by known chemical reactions; and heat flux of 10 s of kJ, measured to 6σ significance, over and above input electrical energy, indicative of unknown exothermic reactions. Six out of six nuclear track detectors, utilized in experiments and interrogated for tracks post-experiment, produced positive results that our team attributes to thousands of individual particle impacts in dense clusters, likely with energies between 0.1 and 20 MeV. Similar nuclear particle, thermal, and RF results have separately appeared in prior reports, but in this work, all three categories of anomalous behavior are reported. Results indicate that the 2013 procedure may be a useful guide toward a set of highly repeatable reference experiments, showing initial but not overwhelming evidence of a new scientific phenomenon. Repeatable recipes are shared so that other groups may replicate and extend the present work.

Electrical energy input efficiency limitations in CO2‐to‐CO electrolysis and attempts for improvement

AbstractElectrochemical CO2 reduction is a potentially up‐coming technology to convert anthropogenic emitted CO2 into chemical feedstock. Due to alkaline operating conditions of CO2‐electrolyis in gas diffusion electrodes, exothermal hydroxide ion neutralization with the excess of supplied CO2 leads to unavoidable electricity‐to‐heat conversion at the cathode, therefore limiting electrical energy input efficiency. The decomposition reaction of carbonates by protons from water oxidation completes the inherent CO2 transport at the anode. In this work, different production routes to CO are thermodynamically examined and experimentally validated. Using formic acid as an intermediate towards CO the electrical energy input efficiency can rise to 71% on a thermodynamical basis. Additionally, the possibility of altering the mechanism of CO2 reduction under acidic conditions is investigated, which would lead to even larger electrical energy input efficiencies. The concept was investigated by pH series measurements (pH = 0–6) at 50 mA/cm2 where Pb derived from Pb3O4 was used as a CO2 reduction catalyst. The reduction to formic acid under acidic bulk electrolyte pH is stable at FEHCOOH = 70% down to pH ≈ 1, while HER is becoming dominant below. Even under such acidic bulk electrolyte conditions no change in reduction mechanism could be forced, which is reflected in invariant cell voltages in the model experiment.

Integrated Studies of Electrophysical Processes in Steam Turbines

The paper deals with comprehensive research in the field of electrization of wet steam flow in a turbine. The experience of the conducted studies on laboratory stands and full-scale objects (CHP and TPP) in Ukraine and the USA is introduced and generalized. It was shown that in the process of steam electrization, the charge density in the flow can reach very high values (an order of magnitude appears to be higher than in a thundercloud), and this phenomenon mainly has a negative effect on the turbine operation. Statistical data on the charge formation of the steam flow in the low-pressure cylinder of the turbine are presented. Results of the research to establish the main electrophysical factors of influence on the surface strength of the blade, such as electric fields, charge density and their polarity, are presented. The research results showed that such factors as the presence of a positively charged steam flow, constant and variable electric fields, which were most often recorded at operating turbines of CHPs and TPPs, significantly (by two or more times) intensify erosion-corrosion processes on the metal surfaces of the blades, thus reducing their working resource. Thermodynamic processes are studied both under conditions of natural electrification of a high-speed flow, which reduce the efficiency by about 0.3–0.35%, and under the influence of artificially created electric charges, which make it possible to increase the efficiency of the steam expansion process in the turbine by 2 or more percent. Various options of local input of electrical energy for steam ionization in the turbine are considered. At the same time, it is noted that for the practical implementation of these approaches, further careful design improvements and tests on model and full-scale installations are required. Water chemistry regimes are also considered in the context of their influence on the flow charge formation process, as well as on reliability and efficiency indicators of the turbine. Experimentally at an 800 MW turbine plant in the USA, it was shown that a change in the pH of the medium affects the intensity and polarity of the charge formation of the steam flow. The paper introduces the physical features of this phenomenon and notes the importance of these processes influence on the strength characteristics of the blades. Information on new methods and technologies that could lead to an increase in the operational efficiency and reliability of wet steam turbines, such as methods for input and removal of electrical energy into the flow; rational choice of water chemistry regimes; space charge neutralization, etc., is provided. These comprehensive electrophysical studies, considered in conjunction with thermal processes, can be characterized as a new scientific direction in the theory of steam turbines – thermal electrophysics.

The influence of electric circuit parameters on NOx generation by transient spark discharge

Nitrogen fixation, production of NO and NO2 from N2 and O2 in air, has been investigated with transient spark self-pulsing DC discharges. NO production is boosted by the addition of capacitors and an inductor to the electrical circuit which drives the discharge. The quantity of NO produced per joule of electrical input energy is doubled, though the quantity of NO2 produced drops. The yield of NO is also increased because the modified circuit enables higher discharge currents to be used. NO concentrations as high as 2000 ppm were obtained with input energy densities of around 300 J per liter of input gas, whilst NO2 concentrations were around 150 ppm. This simple modification of the driving circuit may have potential for optimizing the plasma chemistry with other input gas mixtures and for scaling up nitrogen fixation from air.