High Power Generation Research Articles

Design and Experimental Analysis of a High-Power Generator for Gas Metal Arc Welding in Spray Transfer Mode

Design and Experimental Analysis of a High-Power Generator for Gas Metal Arc Welding in Spray Transfer Mode

Coherent high-power terahertz vortex generation with tunable orbital angular momentum based on transverse phase mask shaping

Abstract Terahertz (THz) radiation has become a significant tool in cutting-edge research due to its superior properties. THz vortices with tunable orbital angular momentum (OAM) are particularly attractive to the scientific community due to their well-defined discrete azimuthal phase around the propagation axis. However, the generation of high-power THz radiation with OAM remains a challenge for most existing technologies. In this paper, a new method for generating coherent high-power THz vortices with tunable OAM and frequency is proposed by combining frequency beating and transverse phase mask shaping techniques. Theoretical analyses and numerical simulations indicate that this method can generate coherent THz vortices with peak powers in the tens of megawatts and tunable topological charge numbers.

Synergetic enhancement of moisture-electric generation through interfacial evaporation and active electrode

Ion migration-based moisture-electric generator holds the open-circuit voltage to power portable electronics, the Internet of Things, and wireless transmission. However, most devices still encounter challenges with the attainment of high-density power generation in continuous mode. Here, we introduce a sustainable and high-power density ion-selective bipolar moisture-electric generator that relies on Au-Al electrodes, capillary water supply, and interfacial evaporation. The device generates electricity by exploiting the salinity gradient between the capillary waterways in the photothermal and waste heat layers. This process is synergized by electrochemical reactions of the electrodes, which propel the migration of cations and anions through ion-selective bipolar hydrogels toward the intermediate waterway. It demonstrates a short-circuit current density of 52.2 A m−2 and a power density of up to 33.8 W m−2 over 0.5 cm × 0.5 cm electrodes. Connecting 13 devices in series in darkness successfully illuminates an LED lamp with a rated power of 1 W together with an operating voltage of 2.0–2.8 V. This work offers an off-grid, environmentally friendly, and affordable solution for high-density moisture power generation.

Simultaneous removal of chlorobenzene and Cr(VI) from groundwater using microbial fuel cell with low-cost Si modified ferrihydrite electrodes

Aromatic chlorinated compounds and Cr(VI) in groundwater pose significant challenges due to their resistance. This study explores microbial fuel cells using low-cost Si-modified ferrihydrite (SiFh) electrodes for simultaneous chlorobenzene and Cr(VI) removal. The voltage output of MFC assembled with SiFh modified electrode was approximately 1.63 times higher than the bare electrode, achieving 1.23 times higher in chlorobenzene degradation efficiency. CF-SiFh loaded MFC had the highest power generation and best EET efficiency, which was positive to greatest and fastest chlorobenzene removal. Microbial community analysis identified the dominance of Cupriavidus and Pandoraea in chlorobenzene oxidation, while Lentimicrobiaceae and Rhodobacteraceae were key genera that may facilitate direct and indirect electron transfer within the biofilms. Cr species analysis in solution and solids confirmed it was reduced to Cr(OH)3 or CrxFe1-x(OH)3 coprecipitates at cathode. MFCs with SiFh-modified electrodes thus offer a promising technology for simultaneous chlorinated compound and Cr(VI) removal, promising in contaminated groundwater remediation.

Zero-Trust Zero-Communication Defence against Hybrid Cyberattacks in Distributed Energy Resources Using Mean Field Reinforcement Leaning

As the evolution of smart grids accelerates, distributed energy resources (DERs) emerge as key elements in the transformation of global energy systems. However, the integration of these technologies introduces significant cybersecurity vulnerabilities, notably false data injection (FDI) and a direct load-altering attack (DLAA). Traditional load-altering attacks require a huge attack load and, thus, are not practical to implement. In contrast, in modern DER environments where households become “prosumers” with high-power energy generation, the implications of such attacks are substantially amplified. This paper considers a hybrid cyberattack that includes both FDI and a DLAA, and presents a hierarchical, optimal load adjustment framework that addresses these security concerns. A centralized optimizer first calculates the ideal load-shedding strategies for each substation, which are then securely broadcast to households. To address the complexities at the individual household level, we introduce a novel reinforcement learning algorithm termed Mean Field Deep Deterministic Policy Gradients (MF-DDPG). This algorithm employs mean-field game theory to enable decentrally coordinated decision-making among each household, making it particularly effective in zero-trust scenarios. Through this multifaceted approach, we offer a robust countermeasure against load-altering attacks, thereby enhancing the resilience and stability of advanced smart grids.

Performance studies on group-velocity-matched femtosecond optical parametric generation

We present a comparative study and detailed characterization of high-power femtosecond optical parametric generation (OPG) at 10 MHz repetition rate in the near and mid-infrared by exploiting near-zero group-velocity-mismatch (GVM) in the nonlinear crystals of PPLN and MgO:PPLN. Using a microchip-started amplified Mamyshev fiber oscillator delivering 198 fs pulses at 1064 nm as the pump source and deploying 19-mm-long PPLN and 42-mm-long MgO:PPLN as gain media, we study in detail the influence of crystal length and pump pulse duration on femtosecond group-velocity-matched interaction in the OPG process. The OPG source is tunable across 1445–1577 nm in the signal and 3318–4412 nm in the idler, and can provide average output powers of up to 439 mW in the signal at 1530 nm and 197 mW in the idler at 3550 nm, at slope efficiencies of ∼50% and ∼20%, respectively. Signal pulses as short as 275 fs are obtained using the shorter crystal, while longer signal pulses with similar output powers are generated with the longer crystal. Experimental results are supported by theoretical simulations, providing good agreement. The OPG source exhibits excellent power stability with high spatial quality of M2<1.5 in the signal and idler beams.

Hydrodynamic Flexible Spindle (HydroFlex) Polishing of turbine blade internal cooling channels for oxide removal

Internal cooling channels are essential to turbine blades for high efficiency power generation. Effective removal of aluminum oxide build-up in turbine blade cooling channels is of critical importance to refurbishment and prolonged service life of turbine blades. Conventional internal polishing processes, including abrasive flow machining, chemical polishing, and electrical discharge machining cannot effectively remove the oxide layer within the internal cooling channels due to the complex geometry with high aspect ratio and diameter variation and the electric insulation of the oxide layer. In this case study, we investigated the application of a novel hydrodynamic flexible-spindle (HydroFlex) polishing process to remove the oxide layer within the internal cooling channels of an Inconel 738 turbine blade that was taken out of serve due to oxide build-up. For a 350 mm long cooling channel featured with an inner diameter transition from ϕ4 mm to ϕ2.5 mm, within 12 min, at the grinding wheel rotational speed of 50,000 rpm and 30,000 rpm, HydroFlex was able to completely remove the 14.31 µm thick oxide layer off from the wall of the turbine blade internal cooling channel, improve the channel circularity by 54.7 %, and decrease the channel surface roughness by up to 64.3 %. The results demonstrated the effectiveness of HydroFlex in polishing complex internal cooling channels of turbine blades for oxide removal and potential blade service life extension.

Improving the efficiency of frequency regulation for High-Power diesel generators

This article tackles the optimization of crankshaft rotation frequency regulators in high-power diesel generators. These generators play a crucial role in the energy efficiency of standalone cogeneration plants. The research focuses on determining the optimal number of teeth on the measuring gear. This factor is crucial for ensuring frequency regulation stability. Nonlinear pulse control methods were applied, and transient processes were modeled. The results show how the number of teeth impacts the accuracy of sampling frequency measurement and regulation efficiency. The novelty of this work lies in the comprehensive analysis of how gear teeth affect the regulation process. A method for selecting the optimal number of teeth has been developed. This significantly eases the adjustment of regulators and cuts costs in implementing modern electronic control systems. This work has practical implicatiowns for upgrading energy systems based on diesel generators, promising improved energy efficiency, reliability, and longevity.

Structural multistability for multi-speed wind energy harvesting from vortex-induced vibrations

Abstract Piezoelectric energy harvesters utilizing vortex-induced vibrations (VIV) have been extensively studied for converting wind energy into usable power for microelectronics. In this work, we explore the use of structural bistability to increase the range of flow speeds over which energy can be harvested without the need for complicated assemblies. We propose a harvester system featuring a piezoelectric transducer bonded to a cantilevered bistable composite laminate, which has two distinct equilibrium shapes at room temperature. To enhance the VIV, we attach a cylindrical bluff body to the free edge of the harvester. The structure’s inherent bistability allows for high power generation at two different flow speeds, contrasting with the single synchronization region typical of linear piezoelectric harvesters. We develop a reduced-order model to predict power output across varying flow speeds and validate these predictions through wind tunnel experiments, showing good agreement. Furthermore, we conduct a parametric study to optimize the model parameters for maximum power output. Our results demonstrate that the bistable harvester can generate up to 4.5 mW of power over a wind speed range of 9.3 m s−1–11.7 m s−1, outperforming the limited speed range of traditional linear VIV-based harvesters. This work underscores the potential to design VIV-based energy harvesters capable of operating efficiently across multiple flow speed ranges using a single structure with its dual stable configurations.

Molecular regulation of lignin multi-level structure and conformational evolution for the self-powered fire alarm sensors

Many studies are still limited to focusing on the primary structure of biomass macromolecules, ignoring the impact of the multi-level structure of macromolecules and their conformational evolution on the high-value utilization of biomass. In this paper, a novel and clever strategy is designed and executed to regulate and immobilize the multi-level structure of lignin macromolecules. Lignin with different spatial conformations exhibits differences in physical properties and processability, despite their chemical primary structures being highly similar. In order to clearly and intuitively study the impact of multi-level structures, lignin-based carbon nanofibers (CFs) with high requirements for processing and precursor properties have been selected as the high-value utilization. The introduction of lignin with optimized multi-level structures effectively improves fiber morphology, uniform diameter, and flexibility. The resulting lignin-based CFs exhibit excellent refractoriness, stability, flame sensitivity (response time of only 1 s), and good energy storage properties (specific capacitance up to 226.1F/g). Furthermore, the CFs moist-electric generator has a high power generation efficiency, and the output voltage of a single device reaches 0.649 V and the output current is up to 160 μA. This work may explain a long-standing issue: why do lignin macromolecules with similar primary structures exhibit many differences in physical and processing properties, which is of great significance for promoting the industrial utilization of lignin macromolecules.

Development of integrated packaged single fuel cell short stack based on titanium metal plates for mobile power generation

Bipolar plates (BPPs) and membrane electrode assemblies (MEAs) are the key components for proton exchange membrane fuel cells (PEMFCs), they are alternately arranged to construct a compact stack with high power generation. This stacking method may introduce several issues, such as the difficulties in maintenance, imprecise assembly and sealing. This paper presents a novel integrated packaged single fuel cell that employs titanium metal bipolar plates to construct a short stack with superior sealing performance and working reliability. To predict the performance of integrated packaged single cell, numerical model was developed to analyze the mass transfer of O2, H2 and H2O within the cell, revealing a uniform distribution of reactants and current. A short stack was manufactured with 10 layers of single cells, it retains excellent sealing properties and consistent output across a range of pressure conditions, with a leakage rate deviation lower than 0.03 mL/(min·cell) and membrane current density variation less than 5%. Finally, the electrochemical performance of the integrated packaged short stack was tested, its maximum power is 886.67 mW/cm2. It can achieve a rated output power of 169.14 W and an energy density of 1684.97 mW/cm3. Thus, our developed short stack has high energy utilization efficiency for power generation, and is anticipated to provide a durable power source for drones, robots and new energy vehicles.

Influence factors and improvement scheme on the breakdown behavior of pseudospark switch

Abstract High-power pulse generators are widely used in civil and military fields. The main switch directly determines the output characteristics of the high-power pulse generators, such as the voltage front time (tf). Pseudospark switches (PSS) show a promising future for middle voltage, high repetitive frequency pulse power applications. However, how to further improve the breakdown behavior without reducing its advantages is a challenging task. In this paper, the influence of operating parameters (anode voltage UA and gas pressure p) and structural parameter (number of cathode holes) on the breakdown behavior are investigated, the related mechanism are explained, and specific improvement schemes are proposed. It is found that the tf of the single channel PSS (SCPSS) decreased significantly with increasing p, but hardly varied with UA under moderate p. However, it is not a sound solution to increase the p excessively to reduce tf. Besides, increasing the number of cathode holes can obtain a shorter tf at low pressures (which implies superior repetition frequency performance). However, at 25 Pa, the jitter (which is defined as the standard deviation of tf in multiple tests) of the 2-channel PSS is larger than that of the SCPSS. And the jitter of the 4-channel and 8-channel PSS is also greater than 6 ns and 2 ns, respectively. Through experimental and simulation analyses, it can be explained as the stepwise penetration of the virtual anode and the non-simultaneous ignition of the channels. A scheme to increase the trigger energy (ε) has been adopted to improve the simultaneous ignition probability, while shortening tf and reducing jitter. After optimization, the good ignition probability of the 4-channel PSS has been improved to 82% and the jitter has been reduced to less than 1 ns at 25 Pa and 14.7 mJ.

Experimental study of a high-power generation platform for ocean thermal energy conversion

Ocean Thermal Energy Conversion (OTEC) is a form of power generation that utilizes the temperature difference between the upper and lower layers of the ocean. This paper presents the design and construction of a land-based experimental platform for OTEC using R134a as the working fluid. Through experimental research, we investigated the performance of the thermal energy cycle system under varying external environmental conditions, such as temperature and flow rate. The results show that the net output power of the system increases with the temperature and flow rate of the warm seawater. Similarly, an increase in the cold seawater temperature and flow rate leads to an increase in net output, though the increase is less significant at higher power levels when compared to changes in warm seawater conditions. Adjusting the evaporation pressure to increase the turbine inlet and outlet pressure difference initially increases the output power but then remains constant. The highest recorded output power during testing was 48kW, with the turbine achieving an isentropic efficiency of 80%, and the maximum system efficiency reached 2%. This study provides theoretical basis and empirical data for system design, which can promote the application in the field of OTEC and contribute to the development of renewable energy.

Enabling Sustainable Energy Communities in ASEAN: A Systematic Approach to P2P Energy Transactions on Matakus Island Using IoT and Blockchain

Abstract This paper addresses the need for energy diversification and sustainable development in the ASEAN region by proposing a decentralized peer-to-peer (P2P) energy trading system. PowerChain, a peer-to-peer energy trading platform, is tailored as the designated medium for implementation. PowerChain harnesses the capabilities of blockchain technology and utilizes MQTT and HTTP protocols to ensure security, transparency, and user-IoT interaction. A case study was conducted on Matakus Island, a rural area in Indonesia with high solar power generation potential and a suitable demographic for the study. Currently reliant on diesel-based power generation, the island serves as an ideal location to evaluate the feasibility and benefits of transitioning to a RE-based P2P energy trading system. Based on simulations using 2 types of load and generation from peer providers, it was found that unused energy for type 1 was 815.9 kWh/year and for type 2 was 821.05 kWh/year. So the total unused energy from 10 peer providers on Matakus Island that can be transacted on the Powerchain platform is 1,636.95 kWh/year. This energy can meet the needs of Matakus Island for 93.7 days.In the platform simulation, three experiments were carried out, namely, single type transactions, multiple type transactions, and rejection of energy requests. From these three experiments, Powerchain was able to perform well, where the seller was successfully selected based on the closest distance, and if the closest selection could not be fulfilled, the seller would come from several nearby buyers. And when a selected peer is rejected, the existing algorithm can search for and select a replacement peer.The integrated approach presented in this study demonstrates the viability of using IoT and blockchain technologies to transform the energy market structure and accelerate the transition towards cleaner and more efficient energy systems in ASEAN.

Quantum dot fourth-harmonic colliding pulse mode-locked laser for high-power optical comb generation

Quantum-dot mode-locked lasers have advantages such as high temperature stability, large optical bandwidth, and low power consumption, which make them ideal optical comb sources, especially for wavelength-division multiplexing (WDM) telecommunications, and optical I/O applications. In this work, we demonstrate an O-band quantum dot colliding pulse mode-locked laser (QD-CPML) to generate optical frequency combs with 200 GHz spacing with maximum channels of 12 within 3 dB optical bandwidth. To achieve the high output power of individual comb lines, four channel conditions are implemented at central wavelength of 1310 nm for WDM transmission experiments. Each channel exhibits more than 10 dBm output power with 200 Gb/s PAM-4 and 270 Gb/s PAM-8 modulation capability via thin-film LiNbO3 Mach–Zehnder interferometer modulator without the requirement of any optical amplifications. This high-order QD-CPML is an ideal comb source for power-efficient optical interconnects and large bandwidth optical data transmission.

Two Birds with One Stone: Impedance-Voltage Dual-Mode Low Humidity Sensor Based on LiBr-MOF-801 with High Response.

Dual-mode humidity sensors have received wide attention in recent years due to their great potential in multifunction applications. Herein, following a "two birds with one stone" strategy, a dual-mode and self-powered low humidity sensor based on LiBr-MOF-801 with high response and power generation is proposed. The optimized LiBr-MOF-801-based sensor exhibits impedance-voltage dual-mode sensitivity in the low humidity range of 0-23% relative humidity (RH) with high response (57.1 and 0.61V), small hysteresis (0.3% RH) and good long-term stability at room temperature (20°C). Moreover, an integrated humidity power generator is obtained by series connection of the self-powered humidity sensor within 15cm2, and the output voltage reaches 2.6V with an output power density of 110 nW cm-2, and can be used as energy, supplying power to commercial electronic equipment even in low humidity. This work provides a new sight for fabricating high-performance, dual-mode, and self-powered low-humidity sensors.

Experimental analysis on the thermoelectric effect of various solid-state devices used for direct conversion of thermal energy into electrical energy

In this present investigation, the performance of thermoelectric generators (TEGs) was determined for the TEGs made of lead telluride (PbTe3), bismuth telluride (Bi2Te3), silicon germanium (SiGe), and aluminum oxide (Al2O3). In response to variations in the heat input rate and water flow rate, the electric power generated by the TEG was recorded and studied for the aforementioned TEG materials. During the investigation, the water flow rate to the TEG's cold side was chosen to be 0.5 lpm to 2 lpm in the step of 0.5 lpm, and the thermal energy input rate to the hot side was set at 30 W–120 W in the step of 30 W. Among all the TEGs Bi2Te3 was superior in terms of power generation potential in comparison to other TEGs in all the test conditions. The investigation also reveals that all TEGs appear to have a high-power generation when the cooling water flow rate was 2 lpm and the heat input rate was 120 W. At a water flow rate of 2 lpm for the case of Bi2Te3, the power generation potential was elevated by about 20.3 %, 14.4 %, and 6.5 % in comparison to Al2O3, PbTe3, and SiGe respectively.

A novel racetrack Blumlein pulse forming line.

Pulse forming lines (PFL) are widely applied in high-power pulsed power generators due to their high energy density and great ability with square waveform modulation. However, the three-cylinder coaxial Blumlein line (tPFL), a commonly used PFL structure, has low energy efficiency due to the difference in impedance of the outer and inner lines. In order to increase the outer line impedance and improve the output waveform of the PFL, a racetrack Blumlein pulse forming line (r-B PFL), formed by two inner cylinders, two middle cylinders, and one outer cylinder that resembles a runway shape, is proposed in this paper. The glycerin energy storage technology and the spiral line technology were applied in the PFL. Moreover, the r-B PFL was tested experimentally after its construction, yielding a satisfactory result. The PFL structure in which multiple middle cylinders share the same outer cylinder achieves a higher outer line impedance, leading to a high energy efficiency of the PFL, which contributes to the PFL development trend toward compactness and miniaturization.

Enhanced thermoelectric performance of graphene [formula omitted] junction nanoribbon

We study the thermoelectric transport of the graphene p−n junction under the perpendicular magnetic field. The Seebeck coefficient Sc, the thermoelectrical figure of merit ZT and the power-generation efficiency η are obtained by the Landauer–Büttiker formula combined with the nonequilibrium Green’s function method. Compared to the perfect graphene system, the graphene p−n junction has a zero-transport coefficient plateau (or the transport gap). The sudden jump of the transmission coefficient near the transport gap edge lead to very larger peaks of the Sc and ZT. Especially in the presence of a magnetic field, the perpendicular magnetic field applied to the p−n junction strongly suppresses the conductance, and enhances the Seebeck coefficient Sc and increases the ZT. Moreover, it is found that the Seebeck coefficient Sc and ZT are strongly dependent on the applied perpendicular magnetic field ϕ, the potential drop in the center region of the p−n junction and the center region length M of the p−n junction. This means that the thermoelectric performance of the graphene p−n junction can be easily regulated by changing the magnetic field and the center region lengths of the p−n junction. Finally, the power-generation efficiency η of the graphene p−n junction as a power generator is calculated. It is found that when the Carnot power-generation efficiency is greater than 30%, ZTM can still be greater than 10. The large ZTM value also maintains a high power-generation efficiency, which indicates that the graphene p−n junction has potential applications as thermoelectric devices.

Evaluating the influence of working parameters on the efficiency of a solid oxide fuel cell by conducting sensitivity analysis using electrochemical and thermodynamic modeling

AbstractThis research article presents an investigation conducted through a numerical model to analyze the influence of various operational parameters on the performance of solid oxide fuel cells (SOFCs). The parameters studied include operating temperature, current density, pressure, steam‐to‐carbon ratio, and fuel utilization. The electrochemical model employed the Butler‐Volmer equation, Fick's model, and Ohm's law to calculate concentration, activation, and ohmic losses. The primary focus was on evaluating the generated power and electrical efficiency as performance metrics. The study revealed that increasing operating temperature and pressure resulted in higher power generation and specific optimum points were identified for optimal SOFC operation. Notably, the highest power generated was 812 kW, achieved at an operating temperature of 950 K and a current density of 18100 A/m2. Additionally, decreasing the fuel utilization factor to 55% at 15250 A/m2 led to a power output of 706 kW. Similarly, at a current density of 17150 A/m2 and a pressure of 400 kPa, the fuel cell generated about 780 kW of power. Furthermore, the research demonstrated that reducing the steam‐to‐carbon ratio increased power generation, with an optimum power output of 704 kW achieved at a current density of 16000 A/m2 and a low steam‐to‐carbon ratio. Notably, this point also showcased the improved electrical efficiency of the solid oxide fuel cell. Overall, this study underscores the significance of specific operational factors that significantly impact SOFC performance. By comprehending these parameters, it becomes possible to enhance the utilization of solid oxide fuel cells across various applications.