The bubble covering phenomenon has been considered one of the most critical factors affecting Proton Exchange Membrane Electrolysis Cell (PEMEC) at high current densities. However, the relationship ...between bubble dynamics and electrochemistry has not been clearly defined. This study analyzes the bubble coverage and PEMEC performance under different input conditions and develops a mathematical model of PEMEC incorporating bubble dynamics. The model successfully predicted the polarization curves and coincided with the experimental data. The results show that bubble coverage increases with increasing current density, bubble detachment radius, and temperature. It decreases with increasing pressure and water inlet velocity. Bubble coverage is influenced by temperature, pressure, wettability, current density, and water inlet velocity. Meanwhile, bubbles covering the electrode deteriorate the performance of the PEMEC, leading to higher overpotentials and lower efficiencies, which becomes more apparent with increasing current density. This paper elucidates the relationship between bubble growth/detachment, bubble coverage, and electrochemistry for the first time, and the results can provide a reference for the development and optimization of high-performance PEMEC.
•A bubble dynamic model of a PEMEC was developed and verified by experiments.•Considering Bubble dynamics, bubble coverage and overpotential effects in this model.•Assessing the effects of temperature, pressure and water velocity on bubble coverage.•Bubble coverage results in higher overpotential and lower efficiency.
This research endeavour-investigates the enhanced adaptation of the Laplace-based variational iteration method (VIM) tailored specifically for tackling the Duffing Equation. This is accomplished by ...incorporating the Lagrange multiplier as a strategic tool to effectively address the inherent natural frequency within the Duffing Equation. Using a meticulous comparative analysis, here are juxtapose the analytical outcomes generated by the modified VIM approach with the numerical solution obtained through the application of the renowned Runge-Kutta Fehlberg method (RKF45), implemented by using the powerful mathematical software, MAPLE. Furthermore, by exploring the profound influence of diverse initial conditions on the resulting solution, a diverse array of distinct graphical representations is presented.
In this study, Brushless DC (BLDC) motor, which is commonly used as a drive element in the unmanned aerial vehicle (UAV), electric vehicles, and mobile robots today, is powered by hydrogen ...technologies as environmentally friendly and controlled by a fractional-order PI (FOPI) controller structure. Proton Exchange Membrane (PEM) electrolyzer, PEM Fuel Cell (PEMFC), storage tank, BLDC motor, and motor driver system are modeled and integrated into the Simulink environment in MATLAB. PEM electrolyzer that is energized from the AC grid via the AC/DC converter generates the hydrogen. This generated hydrogen is stored in the storage tank and used by PEMFC to energize to the BLDC motor. The model of the BLDC motor is controlled by using a closed-loop FOPI controller for the variable speed and torque reference values. Parameters of the FOPI are determined by Moth Swarm Algorithm (MSA) optimization method. It is observed from the results that the PEMFC powered FOPI controlled BLDC motor operates stably at high performance for different speed and torque values as expected from the modern drive systems. Furthermore, it is seen that the required energy for the BLDC motor is provided by the PEMFC-PEM electrolyzer system without interruption and the FOPI controlled BLDC motor successfully follows the reference speed values for the different torque values.
•PEM electrolyzer, PEMFC and BLDC motor models are integrated in a system.•BLDC motor is controlled by FOPI controller.•DC-DC converter is controlled by FOPI controller.•Parameters of the controller determined by Moth Swarm Algorithm.
PEM electrolysis based hydrogen generator system model is developed by using Simulink in MATLAB. The model covers the following system components: PEM electrolyzer stack, water pump, cooling fan, ...storage tank, water tank, power supply, control unit and sensors. In simulation, PEM electrolyzer stack model is the most complex component and consists of four parts; anode and cathode modules, membrane and finally voltage calculations module. Efficiency drops and voltage losses in the PEM electrolysis stack are estimated. The overpotentials are investigated as anode and cathode activation, electronic and ionic ohmic resistances. In addition, the loss of the other components is considered. The model is tested against the dynamic changes and it responded with quick outputs. The cell and stack behavior under different conditions (i.e. ranging of temperature and pressure) are examined. The loss of each system component at different current densities is added to the simulation. The study shows that the loss of stack dominates the losses of other components at higher current densities. The simulation counts that the stack and system model can run with different cases and scenarios. It is run for the scenario that it consumes constant power for a high pressure operation. Results show that current drawn by the stack decreases as the voltage increases because of the increasing pressure.
The model is also compared with the experimental results and the model is found to be consistent with the experimental data.
•Mathematical model for a PEM electrolyzer based hydrogen generator is developed.•A dynamic model of a PEM electrolyzer is developed by using Simulink.•The losses from the system components are investigated.•The loss by the stack is the highest among the components at high current densities.
The discrete memristor has aroused increasing interest due to its application prospects. The theory of discrete memory resistors is gradually being refined. In this paper, the generic ...voltage-controlled discrete memristor model is derived from another perspective - the circuit perspective. And the Simulink model of the discrete memristor model was constructed to implement the simulation. To explore the adaptability of the model, nine discrete memristors are proposed and shown to meet the definition of the memristor. As an application, this paper proposes three discrete memristor-based maps, builds their Simulink model, and analyzes their dynamic behavior relying on the parameters and initials of the system and memristor through the bifurcation diagram, Lyapunov exponent (LE), and spectral entropy complexity. The numerical simulation results show that the three discrete memristor-based maps are better than the original ones in chaotic properties, such as sequence complexity, chaos range, and LE.
The objective of this study is to determine which shape and length of speed humps have the fewest side effects at low speed and which hump is uncomfortable at high speed, using computer simulation ...and field survey data from a vibration meter and accelerometer. The MATLAB Simulink model developed by Japan Automotive Model-Based Engineering (JAMBE) was used to determine the vibration of a vehicle on a rough road surface. One-dimensional numerical information representing road surface height was prepared for sinusoidal, trapezoidal, and semicircular profiles, which were used in the Simulink model. Sequential data of the vertical acceleration of the car were obtained from the simulation and compared with field data for verification. After the verification, the acceleration and jerk of each shape were compared at different speeds. The results show that the shape of the slope and length of the hump appear to have a significant effect on car vibration while crossing speed humps.
This paper describes step by step the modelling and simulation of the open loop scalar command for a three-phase induction machine with known parameters, which operates in motor regime. In order to ...change the electromagnetic torque and implicitly the rotor speed, in this paper the solution of applying a positive mechanical torque from outside the machine was chosen, without dynamically adjusting the supply voltage. The chosen mathematical model for the induction machine is the one described by Krause’s equations, written in a stationary reference frame. The simulations were done on the Matlab/Simulink simulation environment and the behaviour of the machine was monitored under the working conditions listed above.
•Seed misses in single seed metering devices can be prevented by varying rotational speed.•Modelling of the seed miss prevention algorithm provides evidence for the viability of the seed prevention ...system.•Seed prevention system tested on laboratory apparatus with a prescribed amount of empty grooves.•Experimental data showed no occurring seed misses at the seed release point.
Precision seed metering devices based on seed singulation principles all suffer from seed miss problems. The majority of researches on single seed metering devices primarily aims to reduce seed misses. This paper focuses on finding the ways and researching the possibility of eliminating seed misses in electrically driven single seed metering devices. A new approach to eliminate seed misses in single seed metering devices based on rotational speed variation of seed metering drum was introduced. The viability of the proposed approach was supported by modeling single and double miss scenarios in MATLAB/Simulink. Modeling results were used to create a novel seed miss prevention system for single seed metering devices. It was further substantiated by conducting a series of laboratory experiments on polyoxymethylene spherical balls with a prescribed seed miss index ranging from 0.1 to 0.2. Tests were made on laboratory testing apparatus built specifically for this purpose. The analysis of experimental results showed no occurring misses at the seed release point when the system was used. From 42 treatments varied by rotation speed, forced misses, and 2 speed increasing modes the maximum deviation in between seed spacing was 1.25 times the theoretical value. The results of the main experiment were supported by conducting a verification experiment on pea seeds with the resulting highest seed miss index equaling 0.001.
Fuel cell technology is one of the most promising, emissions free, energy conversion technology under renewable energy systems because of its wide ability in most of the commercial applications like ...electrical vehicles, building cogeneration and standby power supply. Mathematical models are trusted as important tools for designing and performance analysis of fuel cell based systems. Many mathematical models based on thermal, electrochemical and electrical steady states as well as dynamic have been reported in literature to evaluate performance of Proton Exchange Membrane (PEM) fuel cell, but all these models are complex and needs huge amount of data for modeling and performance testing. The present paper proposes simple, but more realistic MATLAB SIMULINK model for PEM fuel cell to evaluate its performance under different operating conditions. The performance of the proposed model is compared with single practical, 25 cm2 active area, PEM fuel cell for model validation. The presented model is also valid for a stack having any number of cells.
