Output Current Increases Research Articles

Design and performance study of a kilowatt-class PEMFC stack with metal fiber felts as flow fields

The study presents a comprehensive design and evaluation of a kilowatt-class proton exchange membrane fuel cell (PEMFC) stack, wherein stainless steel fiber felts are innovatively utilized as flow fields. The impacts of critical operating parameters, namely operating temperature, pressure, and reactant gas relative humidity, on the performance of the 22-cell stack with an active area of 83 cm2 were thoroughly investigated. An analysis of the voltage consistency among individual cells was conducted across varying operating conditions and output currents. The total power output of the PEMFC stack reaches 1183W under the fundamental operating conditions, where each cell achieves an average voltage of 0.6V. As the operating temperature and pressure are incremented, the stack’s output power exhibits a noticeable increase. The optimal range for the reactant gas relative humidity is found to be 60% to 80%. As the output current increases, the voltages of individual cells gradually decrease and the voltage consistencies tend to deteriorate. The optimal operating conditions for achieving the best voltage consistency vary with current density.

Synergistically enhanced PVDF-based nanofiber membranes randomly embedded with ZnWO4@PDA nanorods for self-powered sensors with multi-mode free switching

In spite of the high level of attention paid to multifunctional sensors, the flexible and multifunctionality are still intractable challenges to be tackled. Herein, we design a flexible, hydrophobic and stable multifunctional sensing material by electrostatic spinning of PVDF/ZnWO4@PDA (PZP). The incorporation of ZnWO4@PDA into PVDF nanofibers can act as an effective nucleating agent and photosensitizer, which increases the polar crystalline phase and photovoltaic properties of PVDF. With the synergy of PVDF and ZnWO4@PDA, PZP based piezoelectric sensors offer significantly superior electrical output (28.4 V, 600 nA) and high sensitivity (1.04 V/kPa). Moreover, it is particularly surprising that photoelectric sensor based on PZP textiles has excellent optical properties, as confirmed by the response/recovery time (0.6 s/0.66 s) of simulated sunlight detection. Piezoelectric photoelectric effect exists in PZP textiles, as evidenced by the significant increase in the strain output current of photoelectric sensor when irradiated with sunlight. Furthermore, based on the coupling of piezoelectric effect and triboelectric effect of PZP composite, the contact out nano-triboelectric generator has enhanced the electrical output and electromechanical conversion efficiency. Therefore, this work has successfully prepared multifunctional sensing materials that integrate pressure sensing, audio recognition, underwater communication, optoelectronic detection and triboelectric energy collection, paving a new way for the flexible multifunctional sensors.

Effects of NaOH Concentration and Plate Surface Texture on the Performance of the HHO Generator

The need for clean energy as an alternative is inevitable. HHO gas has received much attention lately. In addition to electrolyte concentration, the breakthrough with a diverse electrode surface texture approach has not been extensively performed. Therefore, this study aims to determine the effects of NaOH concentration and plate surface texture on the performance of the HHO generator. In general, the increase in electrolyte concentration combined with surface texture caused an increase in output current, HHO gas production, and output temperature. As for the applied voltage variation with various surface textures, the increase in output current, HHO gas production, and output temperature also took place, similar to the case of increasing NaOH concentration. Either an increase in electrolyte concentration or an increase in applied voltage triggers faster ion movement, leading to an increase in conductivity, thus effectively assisting the electrolysis of water. Regarding the output current and HHO gas production, the textured surface had a much higher value than the plain surface in terms of increasing NaOH concentration or applied voltage variations. However, according to the R2 results, the linear surface has a stronger relationship with the output current and HHO gas production than the cross surface. In the case of the output temperature, the linear surface was slightly lower than the cross surface. It is possibly due to impurities in the electrolyte solution that contaminate the electrode surface, resulting in a lower output temperature on the linear surface.

Process Intensification and Performance Assessment of Sputtered Gadolinium Doped Ceria (GDC) Barrier Layer in Large-Area Solid Oxide Fuel Cell Short Stack

In recent years, Gadolinium Doped Ceria (GDC) barrier layers have been reported to enhance the performance of Solid Oxide Fuel Cells (SOFCs)by reducing cathode/electrolyte interface diffusion and improving ionic conductivity. Prior investigations have demonstrated that GDC thin film sputtered at room-temperature yields substantial enhancements in Solid Oxide Fuel Cells (SOFCs).This enhancement is evidenced by a noteworthy increase in output current (+78%) and a considerable reduction in ohmic resistance (up to -42%), compared to conventionally screen-printed industrial SOFCs. To probe the intricate interplay between morphology and stoichiometry, which fundamentally determines the Ce3+/Ce4+ ratio governing both ionic and electronic conductivity, this study utilized quantitative X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS) techniques. Results revealed that annealing parameters played a role in the number of available oxygen vacancies in the oxygen-reduction reaction (ORR), inducing different changes in the investigated samples. Non-destructive investigations utilizing Distribution of Relaxation Time (DRT) analysis were conducted on two short stacks with varying thickness, employing different sputtering Modalities. These studies revealed that thickness significantly influences the ultimate performance.

Enhanced Acetone Sensing at Room Temperature using Tailored Co3O4 Nanostructures-Coated Optical Fibers: An Application towards Non-invasive Blood Glucose Sensor

Detection of acetone molecules is of paramount importance in the fields of healthcare, air quality monitoring and industrial uses. Herein, we proposed a room temperature Co3O4 nanoparticles coated optical fiber acetone gas sensor. Structural, morphological and uniformity coating of synthesized Co3O4 nanoparticles were investigated using X-ray diffraction and electron microscopy techniques. Interestingly, sensing studies uncovered the linear characteristic in output detector current with change in 0-2.5 ppm acetone concentration for all the sensors (named as F-S350, F-S500 and F-S1000 sensors coated with nanoparticles annealed at 350, 500 and 1000°C, respectively). The F-S350 sensor divulged a significant increase in output current, sensitivity around 15 times higher and reduced limit-of-detection (LoD) values with regard to F-S1000 device. Furthermore, the sensing parameters were augmented by exposed to lower acetone concentration. The experimental findings established the F-S350 sensor as a superior device, which is explained by the evanescent field distribution outside coating region of fiber through FDTD simulation. Typically, the concentration of acetone gas in diabetic patients is above 1.8 ppm than healthy people (range 0.3-0.9 ppm), and therefore the proposed room temperature F- S350 device having LoD value 0.15 ppm can be deemed as a biomarker for the detection of acetone molecules in diabetic patients.

Effect of KOH Concentration on the Performance of HHO Generator at Varying Plate Surface Textures

In an effort to improve the performance of the HHO generator, the surface texture of the electrode plate has been introduced through this study. Optimization of the HHO generator’s performance has been developed continuously in many parts of the world. Therefore, the effect of KOH concentration on the performance of the HHO generator at different plate surface textures was investigated in this study. The HHO generator used in this study combines wet and dry cells. Generally, the results showed an increase in output current, HHO production rate, and output temperature, and conversely, a decrease in operating time due to the effect of increasing KOH concentration and different surface textures. The output current exhibits a significant increase of over 200% for all types of plate surfaces. For the output temperature, the smallest increase of about 9.7% is achieved by the linear plate surface. Meanwhile, the best HHO gas production rate is 267.26 L/min with an operating time of only 112.25 s, which occurred on the surface of the linear plate. Briefly, increasing the KOH concentration followed by modification of the plate surface has yielded better results compared to the plain surface. As for the surface texture, it causes a change in the plate surface area, which has a positive impact on the performance of the HHO generator.

Generating performance of a tubular permanent magnet linear generator for application on free-piston engine generator prototype with wide-ranging operating parameters

This paper proposes a tubular permanent magnet linear generator (TPMLG) applied to the free-piston engine generator and establishes a test rig of the TPMLG. A large amount of experimental data was obtained under unfired conditions and a 2D finite element model of the TPMLG was developed and validated. Then, the electromagnetic characteristics were analyzed under no-load and load conditions. The effects of motion profile, operating frequency, velocity, stroke length, oscillation center position and load resistance on the output performance and generating efficiency (η) of TPMLG were investigated. Results show that the phase angle and distortion rate of the output voltage and current will vary under different motion profiles. As the operating frequency, velocity and stroke length increase, the output voltage, current, power and loss power increase gradually, while η increases at first and subsequently plateaus. When peak velocity is fixed and stroke length increases, both output power and copper loss rapidly increase and then remain steady. Meanwhile, there is only a slight change in generating efficiency. There is an optimal load resistance of approximately 6 Ω needed to achieve maximum output power. When load resistance is greater than 40 Ω, changes in load voltage, current and η become insignificant and the η reaches a maximum of 92.54%. Furthermore, the OCP changes the load voltage and current curves but has little effect on output power in terms of the RMS value.

Factors influencing the thermoelectric characteristics of a thermoelectric generator with cold-side micro heat pipe arrays

The thermoelectric characteristics of a thermoelectric generator with cold-side micro heat pipe arrays are studied owing to their excellent heat dissipation performances. The influence of bending angle and vertical height of micro heat pipe arrays on the cold-side of a thermoelectric generator is examined. The bending angle influence factor is defined to analyze the changing law of thermoelectric characteristics. Three bending angles, five vertical heights, and nine temperature operating points are experimentally estimated with coupling parameters. The temperature difference, output power, and output current increase with increasing heat source temperature. Moreover, the growth trend of output characteristics does not show a significant slowdown over a period of time, indicating its reliability. The thermoelectric characteristics at a 130° bending angle are higher than those at other bending angles owing to the optimum capillary flow, condensation liquid backflow, and small evaporation thermal resistance of micro heat pipe arrays. The optimum vertical height changes as bending angle changes. Furthermore, the output power increases with increasing vertical height at a high heat source temperature. The innovative application of the micro heat pipe arrays in the cold-side heat dissipation of a thermoelectric module has great engineering significance for the optimal design of thermoelectric generators.

A Current-Control Strategy for Grid-Connected Converter Based on Inductance Non-Linear Characteristic Compensation

Inductance is a necessary device for a grid-connected converter (GcC) to attenuate the switching-frequency harmonics in injected grid currents. However, in practice, the inductance decreases with an increase in output current. Especially when the amplitude of sinusoidal currents is higher, the inductance will vary over a wide range as the current value changes in a period. This variation may lead to system instability and cause output current fluctuation. To solve this issue, the model of the GcC with a proportional resonant regulator is firstly built, and the system stability with different current values is analyzed using the Nyquist criterion. The results show that the system stability decreases with an increase in current absolute value. Further, a loop gain compensation unit is embedded into the current regulator to maintain the loop gain constant and ensure the stability of the system under a wide variation range of current values. With this scheme, the compensation unit is only determined by the rated value and the non-linear characteristic of the filter inductance. Therefore, the loop gain compensation unit is independent of the original control system, and the traditional controller parameter design method can also be inherited. Finally, the simulated and experimental results from a 50 A static var generator (SVG) with wide filter inductance variation (using Mega-Flux core) have verified the correctness of the analyses and the effectiveness of the proposed method in this paper.

Fuel vehicle improvement using high voltage gain in DC-DC boost converter

Fuel cell electric vehicles (FCEV) are becoming increasingly popular among manufacturers as carbon dioxide emissions and fuel economy rules have become more stringent. Fuel-cell vehicles often have lower output voltages than those required by the DC bus; therefore, the output voltage decreases rapidly as the output current increases. In this critical circumstance, it is essential to have a DC-DC converter for FCEVs with a high switching frequency and voltage gain. Furthermore, DC-DC booster converters are used in FCEV systems to achieve a high voltage gain. Over a 40 V input range, MATLAB tests the modified converter for gains of approximately five times the input voltage gain. Furthermore, when the fuel cell was operational, a converter efficiency of approximately 90% was measured.

Investigation of the Effect of Solar Panel Temperature on Power Output Efficiency in Brass, Nigeria.

Background: Luminous efficacy is a property of light sources, which indicates what portion of the emitted electromagnetic radiation is usable for human vision relative to the overall efficiency of a light source for illumination. This also applies to solar panels. Purpose: To confirm the possibility of using solar panel as an alternative source of generating electricity and to highlight hindrances to the maximization of solar panel efficiency in the Niger Delta region of Nigeria using Brass as a case study. Materials and Methods: A Modern digital instrument, BK precision model 615 digital light meter and Alda AVD890C digital multimeter, were use for measurement of solar radiation, current and voltage respectively, under varying conditions of temperature. Result: An average Solar panel temperature of 26.2 oC was recorded in the morning hours. Towards noon, solar panel temperature increased up to 45 0C. Output current also increased from 0.0 to 20.0 x 10-1A. Solar panel temperatures between 26oC and 45oC appeared to favour increase in output current. Above 45oC, output current began to drop despite further increase in solar panel temperature. The best solar panel operating temperature in Brass is 45oC. Between the solar panel temperatures of 26oC and 32oC, output voltage remained relatively stable varying between 8.0V and 8.10V. Conclusion: Within limits, solar panel efficiency appears to be temperature dependent up to a maximum temperature, increasing up to 87.0% at 43.8oC. Higher temperatures appear to be counterproductive on solar panel efficiency.

Enhanced-performance droplet-triboelectric nanogenerators with composite polymer films and electrowetting-assisted charge injection

Droplet-Triboelectric nanogenerators (droplet-TENGs) are a promising renewable energy resource. Enhancing the dielectric surface properties is a primary requirement to increase the output performance of TENG device. In this study, droplet-TENGs are fabricated on indium tin oxide glass substrates with either (1) a pure amorphous fluoropolymer (AF) dielectric film; (2) a composite AF film doped with silk powder (AF/Silk); or (3) a composite AF film doped with polytetrafluoroethylene (PTFE) particles (AF/PTFEp). The energy-harvesting performance of the three devices is examined experimentally with and without the application of electrowetting-assisted charge injection (EWCI). For the AF and AF/Silk devices, the output current increases by approximately 12 times following the application of EWCI. Furthermore, the composite AF/Silk device also improves the current stability. The AF/PTFEp TENG increases the output current by approximately 5 times compared to that produced by the TENG with a pure dielectric layer. Moreover, the performance improvement increases to around 25 times following the application of EWCI. For all three devices, the output current increases with a reducing dielectric layer thickness. The output current also increases with an increasing concentration of the droplet solution. Overall, the results presented in this study provide a useful general understanding of the mechanisms underlying the operation of droplet-triboelectric nanogenerators. This research explores, for the first time, the effect of EWCI on composite material used for droplet-TENG and suggests possible strategies for enhancing the performance of such devices through an appropriate design of the dielectric layer and operating conditions.

Effects of a flexible ion gel as an active outer-layer when in contact with a metallic electrode

In this work, the effect of an ion gel outer-layer stuck on top of ITO/PBT/Sn devices was investigated towards its effects on the electrical properties. When this external electrolyte film is in contact with any top permeable electrode, it produces a self-biasing effect and changes the charge carriers’ injection properties. The outer-layer promoted situations where the output current increases up to two orders of magnitude and others where the output current decreases one order of magnitude in comparison to the same samples without it. Admittance spectroscopy measurements were made and the proposed equivalent circuit model indicates that the interfacial electrical properties dominate charge carrier injection face the bulk properties when the outer-layer is present. All the changes observed here are reversible after the ion gel is detached and replaced, indicating that ions do not diffuse into the active layer. The observed results can contribute to improve the current density in certain sandwich structures as well as notify that electrolyte external films can behave as an active layer promoting electrical changes into sandwich devices and can be extended to cases where the electrolyte film is used as substrate.

Power and Current Limiting Strategy Based on Droop Controller With Floating Characteristic for Grid-Connected Distributed Generations

The Grid-Connected Droop-Controlled Distributed Generations (GCDCDGs) are widely used in power systems. However, their power flow is very sensitive to the Upstream Grid (UG) frequency and voltage magnitude fluctuations. This paper focuses on the power and current limiting of inverter-interfaced GCDCDGs under UG frequency and/or voltage magnitude drops. GCDCDG output power and current increase under the UG frequency drop, and if this increase exceeds the maximum of them, current limiters are saturated and according to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P\sim \omega $ </tex-math></inline-formula> droop characteristic the GCDCDG frequency does not track the UG frequency, and this frequency difference leads to power oscillation between DG and UG and the system becomes unstable. In this paper, a new strategy based on the droop-control method is proposed to limit the output power and current of GCDCDGs without using a current limiter that realizes a stable operation under the mentioned conditions. In the proposed method instead of increasing the droop coefficients to limit <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> at their constraints, the droop curves move down after powers and currents exceed maximum values, using two supplementary control signals. The performance of the proposed method is demonstrated with simulation results using MATLAB/Simulink environment under several case studies.

Improving the Reliability of DC-DC Power Supply by Reserving Feedback Signals

The paper deals with the problem of improving the reliability of DC-DC power supplies with pulse-width modulation. The topicality of the work is related to the importance of power supply issues in modern electronics, since the quality of operation of consumer electrical appliances, including critical ones, directly depends on the serviceability of sources. The object of the study is feedback circuits aimed at stabilization of the parameters of power supply of consumers. Failures of the mentioned feedback circuits most often occurs due to the electronic components degradation under harsh operating conditions as well as under severe mechanical overloads. Such failures are dangerous for uncontrolled increase of power supply output voltage and output current. To avoid this, a new method of reserving voltage feedback signals is presented in the paper which is implemented on the basis of flyback supply topology. Feedback signals are formed from the optocoupler located on the load side and from the auxiliary winding of the power transformer, together forming two independent output voltage control circuits. Only one circuit performs stabilization at any given moment of time. If one of these circuits fails, the second one can simply replace it in its operation. The proposed method does not require any digital signal processing algorithms or microprocessor control modules and can be implemented on the basis of cheap, widely available analog chips that perform pulse-width control of the output voltage. As a result, the problem of sudden feedback loop failure is solved and the reliability of electrical equipment is increased. The validity of the proposed method is confirmed by the results of computer simulation with the use of MatLab-Simulink environment. The obtained results can be used in design of fault-tolerant secondary power supplies that operate in harsh operating conditions.

Mathematical modelling for solar cell, panel and array for photovoltaic system

Renewable energy is considered as next alternative to fossil fuels and nowadays, it attracts much attention in agriculture and environmental protection. Application of solar photovoltaic system is drying and dehydration of products, heating, irrigation, greenhouse and power generation etc. Temperature and sun radiation varies nonlinearly. Power generation varies with reference to radiation and temperature in photo-voltaic (PV) system. PV characteristic is nonlinear and PV cell is the basic unit for electricity generation. To get the characteristic response of PV, it aimed to develop a solar cell/panel model and array on a platform like MATLAB. In this research paper, step by step procedure has been defined for modelling solar cell, panel, and array models of the photovoltaic system. Kyocera solar KC-200GT 200W solar panel is used as a reference model for further modelling. The PV array characteristic are simulated for different irradiance(200W/m2,400 W/m2 ,600 W/m2 ,800W/m2 ,1000W/m2)and temperature variation(25°C, 35°C, 45°C, 55°C, 75°C). The output characteristic of the reference model matches with simulated results. The output reduced when the solar irradiation reduced from 1000 to 200 W/m2. As the temperature increased, the output voltage decreases, whereas the output current increases slightly. This model would be useful for investigating the effect of different parameters like series resistance, shunt resistance, thermal voltage, solar cell temperature coefficient of short circuit current etc. It would also be useful for investigating the working parameters like temperature &amp; radiation condition and different series and parallel combinations of panels. This modelling is useful in investigating the performance of solar arrays in different applications of solar power generation, as well as modelling provides a major role in the mounting of PV panels.

Design and Analysis of Single Switch Transformer Less DC-DC Converter with Universal Input Voltage for Fuel Cell based Vehicles

A new single switch solar powered high gain step-up DC-DC converter is proposed for plug-in hybrid battery charger in Electric vehicle (EV). The proposed topology utilizes a L2C3D2network to obtain high voltage gain and reduce the voltage stress on the power switch. Additionally, the proposed converter has a universal input voltage in order to suit the soft output characteristics of the fuel cell. The fuel cell has a relatively low output voltage and high current, and it has soft output characteristics as its output voltage drops as the output current increases. Therefore, the fuel cell cannot be directly interfaced to the dc-link bus (400V) of the inverter inside the EV. This dc-dc converter has a universal input voltage feature with wide voltage gain range to suit the soft output characteristics of the fuel cell. Additionally, this dc-dc converter has to have low input current ripple to prolong the life time of the fuel /solar cell, and a common ground between its input and output ports to avoid additional EMI and maintenance safety problem. This control strategy is modelled and simulated using MATLAB -Simulink. A proto type experimental has been fabricated and tested. The experimental analysis was done and the results are in line with the simulation results.

Hybridized Triboelectric‐Electromagnetic Nanogenerator for Wind Energy Harvesting to Realize Real‐Time Power Supply of Sensor Nodes

AbstractAs the power consumption of various electronic devices is gradually reduced to milliwatt or even microwatt level, it is possible to achieve self‐powered electronic devices by obtaining weak energy from the environment. In this article, a hybrid nanogenerator that contains two working parts, —the triboelectric nanogenerator (TENG) in sliding independent layer mode and the electromagnetic generator (EMG) in rotating mode, is reported. The hybrid generator can effectively broaden the output voltage range while shortening the voltage boost time. After polishing the surface of nylon film with different mesh sandpaper, the maximum increase of output voltage and current can reach 60% and 80%, respectively. When the wind speed is 9 m s–1, the maximum average output power values of TENG and EMG are 0.33 and 32.87 mW, respectively. Also the hybrid nanogenerator can stably power 200 light‐emitting diodes (LEDs) and hygro‐thermograph after working for 2 s. Compared with the method of supplying power to electronic devices after a long period of energy storage, the triboelectric‐electromagnetic hybrid nanogenerator that is designed can realize real‐time power supply for wireless sensor nodes and Bluetooth modules at a wind speed of 10.5 m s–1, and the voltage at both ends is always maintained dynamic equilibrium.

High‐performance flexible piezoelectric nanogenerator based on necklace‐like PZT particle chains

SummaryFlexible piezoelectric nanogenerators (F‐PENG) as a clean, green power generation device have attracted much attention. Dielectrophoresis (DEP) was used to prepare flexible piezoelectric nanogenerators with necklace‐like oriented structure. The results showed that the oriented structure significantly improved the electrical output performance of F‐PENG by enhancing the stress and free charge transmission. For the F‐PENG with 8 vol% oriented PZT particle, open‐circuit voltage and short‐circuit current reached 176 V and 35 μA and an instantaneous power of up to 2 mW was collected for an optimal matched load resistance of 6 MΩ. Output voltage and current increase by 135% and 133%, respectively, compared with the F‐PENG with random structure. Meanwhile, the finite element simulation results also confirmed the superiority of this oriented structure. There was a clear linear relationship between the output voltage and pressure, and the sensitivity was 1.13 N/V. The oriented PZT particle‐based F‐PENG with excellent electrical output performance has great application prospects in the fields of green power generation and self‐powered building monitoring system.

Influence of output current on decolorization efficiency of azo dye wastewater by a series system with multi-stage reverse electrodialysis reactors

A series system with multi-stage reverse electrodialysis reactor (REDR) can harvest salinity gradient energy (SGE) from working fluids as much as possible to treat organic wastewater. In this paper, the series system simulated with a single REDR system to degrade azo dye wastewater was investigated experimentally. The results showed that the series system could not only degrade azo dye wastewater effectively, but also output a certain of electric energy simultaneously. In the series system, the salinity gradient variations of working fluids which flowing through each stage REDR affected only on the output voltage of each stage REDR, but which almost did not affect on the decolorization efficiency of azo dye wastewater of each stage REDR. However, the output current variations of the series system effected significantly on the decolorization efficiency. Although the increase of output current was benefit to the decolorization efficiency for each reactor in the series system, the number of reactors in the series system will reduce quickly, which results in total decolorization rate of azo dye wastewater decrease. When the current was 0.1A, the overall performances of the series system would be relatively optimal under the experimental conditions. The number of reactors, total decolorization rate of azo dye wastewater, utilization efficiencies of SGE and membrane area, and net output power could reach 19, 1.91 mg·s−1, 6.92 mg·J−1, 31.21 mg·m−2s−1 and 0.68 W, respectively.