Induction heating (IH) applications, assisted with converter topology and their control, have become very attractive in recent years. Independent power control for any induction cooking application ...with simple converter topology, multi-load handling capacity, and a control technique is still a research hot spot. This paper focuses on developing the dual-frequency converter for delivering power to two loads independently. The switching frequencies of the converter for loads 1 and 2 are selected as 20 and 80 kHz, respectively, and the inverter is operated by multiplexing two switching frequencies. The independent power control is performed using a phase shift control scheme and validated in real-time using a PIC16F877A microcontroller. The prototype of 1 kW is developed and load 1 is operated with 550 W and load 2 is operated with 270 W output power. The independent power control is verified for various values of the control angle (ϕ) and it is noticed that the efficiency is 91% at 0° and it is above 80% for other values of ϕ. The thermal model of the proposed system is studied using COMSOL multiphysics software and the experimental image is recorded using a FLIR thermal imager. It is noted that the temperature rise in the load is 78 °C and 38.5 °C for loads 1 and 2, respectively, at time t = 180 s.
Photothermal therapy is a local treatment method for cancer and the heat energy generated from it could destroy the tumor cells. This study is aimed to investigate the temperature distribution in ...tumor tissue and surrounding health tissue of tumor bearing mice applying mathematical simulation model. Tumor bearing mice treated by laser combined with or without indocyanine green. Monte Carlo method and the Pennes bio-heat equation were used to calculate the light distribution and heat energy. COMSOL Multiphysic was adopted to construct three dimensional temperature distribution model.
This study revealed that the data calculated by simulation model is in good agreement with the surface temperature monitored by infrared thermometer. Effected by the optical parameters and boundary conditions of tissue, the highest temperature of tissue treated by laser combined with indocyanine green was about 65 °C which located in tumor tissue and the highest temperature of tissue treated by laser was about 43 °C which located under the tumor tissue. The temperature difference was about 20 °C. Temperature distribution in tissue was not uniform. The temperature difference in different parts of tumor tissue raised up to 15 °C. The temperature of tumor tissue treated by laser combined with indocyanine green was about 20 °C higher than that of the surrounding healthy tissue.
Reasonably good matching between the calculated temperature and the measured temperature was achieved, thus demonstrated great utility of our modeling method and approaches for deepening understand in the temperature distribution in tumor tissue and surrounding healthy tissue during the laser combined with photosensitizer. The simulation model could provide guidance and reference function for the effect of photothermal therapy.
Electroforming is increasingly gaining recognition as a promising and sustainable additive manufacturing process of the “Industry 4.0” era. Numerous important laboratory-scale studies try to shed ...light onto the pressing question as to which are the best industry approaches to be followed towards the process’s optimisation. One of the most common laboratory-scale apparatus to gather electrochemical data is the rotating disk electrode (RDE). However, for electroforming to be successfully optimised and efficiently applied in industry, systematic scale up studies need to be conducted. Nowadays, well-informed simulations can provide a much-desired insight into the novelties and limits of the process, and therefore, scaling up modelling studies are of essence. Targeted investigations on how the size and geometry of an electroforming reactor can affect the final product could lead to process optimisation through simple modifications of the setup itself, allowing immediate time- and cost-effective adjustments within existing production lines. This means that the accuracy of results that any scaled up model provides, if compared to a successful, smaller scale version of itself, needs to be investigated. In this work a 3-D electrodeposition model of an RDE was used to conduct geometry and model sensitivity studies using a commercial software as is often done in industry. As a next step, a 3-D model of an industrial-scale electroforming reactor, which was
90
times larger in electrolyte volume compared to the RDE, was developed to compare, and identify the key model parameters during scale up. The model results were validated against experimental data collected in the laboratory for both cases to assess model validity.
In the geosciences, inverse problems, wherein observations corresponding to model outputs are known and model parameters are unknown, are commonplace. Many of these problems involve coupled physical, ...chemical, and other processes that can be modelled using forward finite-element models. Here, we present a novel interface, COMPEST, that connects the parameter estimation and uncertainty analysis package, PEST, with the finite-element modelling package, COMSOL Multiphysics. To demonstrate some of the capabilities of this approach, we also develop and present a novel model for the degradation and transport of chlorohydrocarbons in low-permeability units. This model integrates isotopic fractionation arising from degradation and diffusion. Three implementations of this model with increasing complexity are used to demonstrate the functionality of the developed interface. This linkage provides a means for parameter estimation, uncertainty analysis, and singular value decomposition to gain insight into the behaviour, identifiability, and interdependence of the various parameters in the model. COMPEST is written so as to be suited to a wide range of scientific and engineering applications and thus can be used to link any COMSOL model with PEST. This enables the use of advanced inverse modelling techniques previously unavailable to COMSOL users.
•COMPEST, an interface connecting PEST and COMSOL Multiphysics, is presented.•Forward finite-element models are used to solve inverse modelling problems.•Novel isotope fractionation models for groundwater contaminants are developed.•Parameter estimation and SVD are demonstrated with the developed models.
Surface-enhanced Raman scattering (SERS) enhancement factor (EF) is among the major applications of surface plasmon polaritons (SPP’s). In this work, the SERS EF of 1D rectangular and ...sinusoidal-shaped gold (Au) grating structures has been designed and optimized on Au film using COMSOL multiphysics (5.3a) RF module taking glass as substrate. The 1D grating models are simulated by variation in slit width ranging 200–600 nm while other parameters including periodicity of 700 nm and Au film thickness of 50 nm remained fixed. In order to study the several phenomena including enhanced optical transmission and SERS EF, the transmission and electric field spectra have been obtained from both types of grating structures. In agreement with fundamental plasmonic mode, the slit width of two-thirds of the periodicity found to be optimum for SERS EF. Remarkable value of SERS EF is obtained in the case of a sinusoidal Au grating device (6.4 × 10
9
) which is calculated to be five times that of the rectangular grating (1.2 × 10
9
). These devices are also the fingerprints of molecules, hence find applications in biosensing, pollution control, and chemical and food industry.
Electrical contacts are important circuit components with diverse industrial applications, and their failure can lead to multiple unwanted effects. Hence, the behavior of electrical contacts is a ...widely studied topic in the scientific literature based on various approaches, tools, and techniques. The present study proposes a new approach to numerical modeling and simulation based on the Holm contact theory, aiming to study the dependence between the electric potential and the temperature within an electrical contact. Structured in five sections, the research was conducted using COMSOL Multiphysics software (version 5.3) and its solid-state mechanics, electric current, and heat transfer modules in order to highlight contact behavior from mechanical, electrical and thermal points of view: the von Mises stress, contact force, electric field amplitude, variation of the electrical potential along the current path, temperature gradient, and dependence of temperature along the contact elements edges were obtained by simulation, and are graphically represented. The results show that the temperature increase follows a parabolic curve, and that for values higher than 4 mV of voltage drop, the temperature of the contact increases to 79.25 degrees (and up to 123.81 degrees for 5 mV) over the ambient temperature, thus the integrity of insulation can be compromised. These values are close (10–12%) to the analytically calculated ones, and also in line with research assessed in the literature review.
Even with an increasing interest in scaling-up Microbial Electrochemical Technologies (MET), it is still common to focus on their “fundamentals”. An important example is the production of current ...density (jmax) by microbial anodes in a three-electrode arrangement (3 EA) configuration, e.g.: a graphite plate of well-defined projected (or geometric) surface area (PSA) and a cathode, both parallel to each other.
With such type of anode within a 3 EA configuration, jmax‘s calculation is expected to be straightforward. Nonetheless, certain issues prevail. Occasionally, jmax is wrongly overestimated neglecting the surface of the anode that does not directly face the cathode.
Here, grown biofilms of the novel electroactive bacterium Geoalkalibacter subterraneus showed that the actual area of anode that contributes to jmax is the total PSA (or apparent geometric area) immersed in the electrolyte available to form a biofilm regardless the side of the anode that faced or opposed the cathode even in a medium with low conductivity such as urban wastewater, a niche of application for METs.
For the sake of normalization, researchers (and especially a “freshman” microbial electrochemist) are encouraged to: A) use the total PSA (or apparent geometric area) immersed in the electrolyte to calculate jmax or B) to cover edges and faces hidden of the anode with an electrical insulator to allow the flow of current on the side of the anode that directly faces the cathode prior calculation of jmax. This normalization can be conducted when the main goal is to quantify (and thus properly report) jmax produced when using (e.g.): a novel i) electroactive bacterium, ii) electrode material or iii) reactor design.
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•Consensus on the anode area contributing to microbial current production is proposed.•Electrochemistry and microscopy confirm the anode area actively producing current.•Total immersed area in the electrolyte should be used to calculate current density.•Sides hidden from cathode shall be electrically insulated to avoid overestimation.
Electrochemical forming (or electroforming), is gaining recognition as an additive and sustainable manufacturing process. Electroforming could shape part of the fourth industrial revolution through ...thoughtful and systematic modelling. For this to be useful, efficient simulation of the electroforming process in the 4.0 era should be used as a tool to design, test and propose optimised processes. Emphasis should be put on building models that provide new information about the electrochemical systems under investigation or lay the groundwork for innovative applications and provide the industry with options to update obsolete process models currently in use. This will lead to a decrease in process waste, lower inventory needs, perhaps meet environmental regulations and optimise supply chains. In this review article, key studies on modelling electroforming processes are critically reviewed against this framework. The authors suggest some useful modelling approaches using commercial software.
To increase the electric power density and efficiency of the thermophotovoltaic system, the studies usually focus on the methods such as photon recycling or the matching of optical properties of ...thermal emission. As multiple parameters affect each other in the thermophotovoltaic system, the optimization of the geometrical parameters in the system is important. In the study, the thermophotovoltaic system was geometrically optimized to obtain more electric power density and system efficiency in the temperature range determined in the combi boiler. For the optimization, the geometrical parameters such as the emitter thickness and distance between the filter-thermophotovoltaic cell were altered. In the first step of this study, a model of the thermophotovoltaic system was designed for the combustion chamber of the combi boiler. In the second step, the lowest and highest temperature for the emitter were determined as 627.15 K and 1251.15 K, respectively. Finally, the thermophotovoltaic system was optimized by using Comsol Multiphysics in this temperature range. The optimum thickness of the emitter, the optimum distance between the filter-thermophotovoltaic cell, the optimum distance between the emitter-thermophotovoltaic cell and the optimum thickness of the filter were determined as 20 mm, 1 mm, 34 mm and 3 mm, respectively. The electric power density and system efficiency vary between 68.63-501.49 W/m
2
and 1-2.52%, respectively. Also, this system has a power output varying between 27-203 W. The results of the study show that the geometrically optimized thermophotovoltaic system provides more electric power density and system efficiency. Therefore, the optimization of the geometrical parameters is important in the design of the thermophotovoltaic system and should be considered.
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