Simulation Of Temperature Distribution Research Articles

Analysis of ozone generation in a planar atmospheric pressure air dielectric barrier discharge reactor

This work investigates O3 production in a planar atmospheric pressure air dielectric barrier discharge reactor numerically and experimentally. The surface temperature of the reactor is measured by an infrared (IR) thermal imager, and the O3 densities of cases in the reactive zone are measured by ultraviolet absorption spectroscopy. The 1.5D plasma fluid model (PFM) with transverse convection is employed to capture the average properties of a single microdischarge (MD) generated in the reactor. The concept of equivalent reaction is proposed to calculate spatial-cyclic average species sources obtained by the 1.5D PFM and provided to the chemical model of a 3D gas flow model (GFM) for obtaining density distributions of reactive species generated by MDs in the reactive zone. The simulated temperature distribution of the reactor surface is validated by that measured with the IR thermal imager since the gas temperature was reported as a critical discharge parameter for O3 generation. The simulated O3 densities show the same trend as the flow rate changes, which demonstrates the proposed model captures the average discharge dynamics in different operating conditions. In the 1.5D PFM, the simulated results show that the O3 molecules produced in the case of 4 SLM are much more than those produced in the case of 1 SLM though the O atoms produced in the case of 1 SLM are around 20% more than those produced in the case of 4 SLM. In the case of 1 SLM, more than 48% of O3 molecular generated are destructed, while only around 14% of O3 molecules are destructed in the case of 4 SLM. The analysis shows that around 73% of O atoms generated in the 1.5D PFM are consumed in the formation of O3 molecules in the case of 4 SLM, while only 18% of O atoms generated in the case of 1 SLM are consumed in the formation of O3 molecules. In the 3D GFM, the O3 destructed is around 24% of that destructed in the 1.5D PFM in the case of 4 SLM due to the oxidation reaction of NO, while only 11% of O3 molecules destructed as that destructed in the 1.5D PFM in the case of 1 SLM. The amounts of O3 molecules generated in the 3D GFM are minor if they are compared with those generated in the 1.5D PFM in all cases. The overall O3 yield efficiency reaches 97 g kWh−1 with the O3 concentration increasing up to 2700 ppm in the case of 4 SLM, while the O3 yield efficiency decreases to 10 g kWh−1 and O3 concentration drops to 1400 ppm in the case of 1 SLM.

Simulation of Temperature Distribution in a Brake Pad Ceramic Composite Material

The temperature distribution is an important aspect of any brake pad composite material. The braking temperature affects the performance and efficiency of any brake pad composite material. It is difficult to measure the interface temperature between the brake pad and disc by thermocouples or infrared thermal sensors during braking. This work investigates the temperature distribution of a ceramic composite brake pad material by the transient thermal analysis method. The transient thermal approach method helps to visualize the interface temperature through simulation. Also, it provides pin temperature at a distance of 4 mm and 6 mm away from the disc surface to observe the temperature distribution of the brake pad. The experimental values of the temperature of the pin at 4 mm and 6 mm away from the disc are collected from the literature and compared with the predicted temperature through simulation. It is found that there is a close agreement between the predicted and experimental temperature values.

Optimized machine learning approaches for identifying vertical temperature gradient on ballastless track in natural environments

Due to the exposure of ballastless track to various geographical and meteorological conditions, the effects of temperature evolution on the performance of ballastless track should be considered. However, accurately predicting the vertical temperature gradient (VTG) on ballastless track in thermal environments has been challenging. This study develops four machine learning (ML) approaches, i.e., support vector regression (SVR), random forest (RF), extreme gradient boosting (XGBOOST), and artificial neural network (ANN), to identify the ballastless track’s VTG evolution in natural environments. The above ML approaches with hyperparameters optimized are trained and tested by 2000 samples from full-scale finite element simulation. The temperature field monitoring on ballastless track is performed to validate its temperature distribution simulation. The results show the XGBOOST-based method has the best accuracy for identifying the ballastless track’s VTG among the four selected ML approaches. Furthermore, the stacking-based hybrid framework is proposed to further improve the four selected ML approaches. For the stacking strategy, the improvement percentage of MAE of performance and transferability to the four selected ML approaches are 11.51%-55.43%, and 42.27%-77.79%, respectively. The proposed ML approaches are proven capable and efficient for predicting the temperature evolution of track engineering.

Improving radio frequency heating uniformity in milled rice with different packaging shapes by changing temperature of forced air

Radio frequency (RF) treatment is a promising physical method for disinfesting and pasteurizing foods but the non-uniform RF heating is still a major obstacle for industrial applications. In this study, a three-dimensional model was established with COMSOL software to simulate temperature distributions in milled rice with different packaging shapes and experiments using a 6 kW, 27.12 MHz RF system were carried out to evaluate the improvement of heating uniform of sample by changing temperature of forced air. The established model was validated by temperature-time histories at three points in the sample and temperature distributions at the top and bottom surfaces. The results showed that the cold spot of the regular shape sample was found at the part with small thickness, and the RF heating uniformity was improved by increasing temperature of forced hot air. When the temperature of forced hot air increased from 40 to 60 °C, all the sample temperatures were above 50 °C, which might meet the required temperature of disinfestation, and the heating uniformity index decreased from 0.113 to 0.099. For the cuboid shape sample, the corner/edge effect was observed and the heating uniformity index firstly decreased and then increased with reduced temperature of forced cold air. When the temperature of forced air decreased to 10 °C, the best heating uniformity of the cuboid shape sample was obtained. The results of this research can help to select packaging shape and improve the heating uniformity of samples for RF treatment in large-scale applications.

Joule heating involving ion currents through channel proteins.

Ion currents associated with channel proteins in the presence of membrane potential are ubiquitous in cellular and organelle membranes. When an ion current occurs through a channel protein, Joule heating should occur. However, this Joule heating seems to have been largely overlooked in biology. Here we show theoretical investigation of Joule heating involving channel proteins in biological processes. We used electrochemical potential to derive the Joule's law for an ion current through an ion transport protein in the presence of membrane potential, and we suggest that heat production and absorption can occur. Simulation of temperature distribution around a single channel protein with the Joule heating revealed that the temperature increase was as small as <10-3 K, although an ensemble of channel proteins was suggested to exhibit a noticeable temperature increase. Thereby, we theoretically investigated the Joule heating of systems containing ensembles of channel proteins. Nerve is known to undergo rapid heat production followed by heat absorption during the action potential, and our simulation of Joule heating for a squid giant axon combined with the Hodgkin-Huxley model successfully reproduced the feature of the heat. Furthermore, we extended the theory of Joule heating to uncoupling protein 1 (UCP1), a solute carrier family transporter, which is important to the non-shivering thermogenesis in brown adipose tissue mitochondria (BATM). Our calculations showed that the Joule heat involving UCP1 was comparable to the literature calorimetry data of BATM. Joule heating of ion transport proteins is likely to be one of important mechanisms of cellular thermogenesis.

УПРАВЛЕНИЕ ГРАДИЕНТОМ ТЕМПЕРАТУРЫ ПО СЕЧЕНИЮ МАССИВНЫХ КОНСТРУКЦИЙ СПОСОБОМ ПОСЛОЙНОЙ УКЛАДКИ БЕТОННОЙ СМЕСИ

The paper considers a method for depositing concrete mixtures into massive structures, which provides a favorable thermo-stressed concrete state. The thermo-stressed state was assessed according to the temperature gradient arising during thermo-curing along the cross-section of a prismatic structure with a surface modulus of 3.1 m–1. The paper analyzes domestic and foreign literature on the maximum allowable values of the temperature gradient and recommends accounting for the influence of the structural reinforcement ratio on allowable temperature gradients along the reinforcement cross-section. It also discusses other means of achieving a favorable thermo-stressed state of concrete studied in previous works. The paper presents the unsatisfactory results of a computer simulation of temperature distribution without concrete mixture layering. These results show the necessity of using effective set retarding admixes to ensure concrete layering without the formation of construction joints. Layering the concrete distributes the heat release process over time and reduces its peak values due to a smaller amount of cement in each layer compared to continuous layering of the entire volume.

Inert ambiance-assisted laser ablation of CVD diamond leads to enhanced surface quality and grindability

Diamond is a versatile ultimate engineering material that has been recommended for numerous purposes, especially micro mills. Laser-assisted precision grinding is substantiated to be a promising approach for fabricating diamond micro tools. Yet, in practice, the short pulses that render express elimination will deteriorate the flatness of the tool surfaces, bringing about a boost in the risk of edge collapse and a shrink in yield during the subsequent precision grinding. The tactic of ambiance-assisted laser ablation, which introduces an auxiliary gas during the irradiation to promote the ablated domain quality, is proposed in this investigation. Specifically, a raster scanning-based transient temperature distribution simulation is erected to comprehend the ablation mechanism of the chemical vapor deposition (CVD) diamond. Additionally, it can be deduced that the inert nitrogen with high cohesive energy curbs the instantaneous deflagration of oxidation on the Knudsen layer and the activity of dangling bonds that are desorbed at high temperatures. The nitrogen-assisted laser ablation of the diamond sample leads to a maximum dwindling in surface roughness of 33% compared to that with non-ambiance-assisted. Subsequently, the laser-ablated surface optimized by an inert atmosphere is precisely ground with a fine abrasive grinding wheel. The detection of the sharp cutting edge ( r β = 1.74 μm) with almost no notch and the ground flank surface with the roughness of 168 nm indicates that accessing the inert auxiliary atmosphere during ablation can enhance the surface quality of the machined diamond and the corresponding grindability.

Simulation of substrate temperature distribution during diamond film growth on zirconia with buffer layers by HFCVD method

Simulation of substrate temperature distribution during diamond film growth on zirconia with buffer layers by HFCVD method

Numerical Simulation of Temperature and Carbon Dioxide Distribution in Indoor Environment Using Two-Equation Turbulence Models

Numerical Simulation of Temperature and Carbon Dioxide Distribution in Indoor Environment Using Two-Equation Turbulence Models

Computational fluid dynamics simulation of hybrid laser-MIG welding of 316 LN stainless steel using hybrid heat source

Hybrid laser-MIG welding (HLMW) process is preferred for welding thick sections (>10 mm) to achieve faster and full penetration weld displaying enhanced productivity due to the synergistic effect of the laser and MIG heat sources in the weld pool. An optimum heat source model combining the effect of the laser and MIG heat source needs to be determined first for the accurate simulation of the weld pool development and temperature distribution during HLMW process. The current study first aims to determine the right hybrid heat source model for welding a 0.01 m thick 316 LN SS plate and then to study its effect on the weld pool dynamics. For this purpose, a three-dimensional (3D) transient model with ANSYS Fluent V.19.2 was designed by hybridizing laser and arc heat sources. Goldak's double-ellipsoidal mode of heat source was favoured for the arc source. A 3D conical, combined 3D conical-cylindrical and rotary Gaussian heat source model were considered for the laser source. The simulated weld pool profile and temperature distribution data obtained for the three hybrid heat sources were validated by carrying out experiments employing HLMW process with optimized welding parameters that achieve full penetration. The numerical modelling has shown that the double-ellipsoidal rotary Gaussian heat source as the appropriate model for HLMW simulation of 316 LN SS. There was good agreement between the simulated weld bead shape, size and the temperature with the experimental result. The synergy effect of the laser and MIG heat sources based on their separation distance was demonstrated using the optimized heat source model to get further insight on the weld pool dynamics and the keyhole penetration.

Time-dependent Monte Carlo continuum radiative transfer

Context. Variability is a characteristic feature of young stellar objects that is caused by various underlying physical processes. Multi-epoch observations in the optical and infrared combined with radiative transfer simulations are key to study these processes in detail. Aims. We present an implementation of an algorithm for 3D time-dependent Monte Carlo radiative transfer. It allows one to simulate temperature distributions as well as images and spectral energy distributions of the scattered light and thermal reemission radiation for variable illuminating and heating sources embedded in dust distributions, such as circumstellar disks and dust shells on time scales up to weeks. Methods. We extended the publicly available 3D Monte Carlo radiative transfer code POLARIS with efficient methods for the simulation of temperature distributions, scattering, and thermal reemission of dust distributions illuminated by temporally variable radiation sources. The influence of the chosen temporal step width and the number of photon packages per time step as key parameters for a given configuration is shown by simulating the temperature distribution in a spherical envelope around an embedded central star. The effect of the optical depth on the temperature simulation is discussed for the spherical envelope as well as for a model of a circumstellar disk with an embedded star. Finally, we present simulations of an outburst of a star surrounded by a circumstellar disk. Results. The presented algorithm for time-dependent 3D continuum Monte Carlo radiative transfer is a valuable basis for preparatory studies as well as for the analysis of continuum observations of the dusty environment around variable sources, such as accreting young stellar objects. In particular, the combined study of light echos in the optical and near-infrared wavelength range and the corresponding time-dependent thermal reemission observables of variable, for example outbursting sources, becomes possible on all involved spatial scales.

Numerical simulation of temperature distribution of heat flow on reservoir tanks connected in a series

The flow of temperature distribution through a medium in thermodynamic studies plays an important role in understanding physical phenomena in chemical science and petroleum engineering, while temperature distribution indicates the degree of reaction that must be undergone to obtain the final product. Therefore, this paper aims to present and apply the exponential matrix algorithm (EMA), differential transformation algorithm (DTA), and Runge-Kutta (RK5) to simulate the temperature distribution in five heating tanks in series. successive preheating of multicomponent oil solutions. A mathematical model of the energy balance equations of the reservoir is considered. Two computer experiments were performed to test and investigate the relationship between two constant parameters appearing in the model. Numerical simulation of saturated steam Tsteam temperature of 500 °C and 1000 °C used to heat the tanks and initial temperature T035°Cand100°C of the first tank feed oil are considered. The fluids in the reservoirs were considered homogeneous throughout the experiment and changes in the cell configuration at two constant parameters were presented in the 2D plot control with the use of the MAPLE 18 software package. The study revealed the nature of the temperature distribution that the higher temperature distribution is obtained when heat is transferred from the first tank to the fifth tank and the reverse reaction occurs in all five reservoirs when ψ = 0.0025 and ω = 0.0025 respectively. Numerical results obtained are prototypes of oil temperature distribution performed under laboratory conditions in a thermodynamic experiment.

Laser etching of 2D materials with single-layer precision up to ten layers

Patterned 2D materials with layer-controlled thickness and precise lateral resolution are of great potential for many applications. Laser etching is a promising technique for large-scale patterning of 2D materials, but better control in film thickness is strongly desired. Here, we explore the dynamic characteristics in the laser etching process in which a local temperature lock phenomenon is observed as laser power reaches the etching threshold. A layer-by-layer etching strategy is then developed based on the temporal evolution of the local temperature as measured by in-situ Raman spectroscopy. Employing such a method in a typical layered material MoS2, we demonstrate thickness control up to ten layers in layer-by-layer laser etching. The local temperature lock during laser etching is explained by thermodynamic simulation of temperature distribution within the 2D material under laser illumination. The influence of substrate thermal conductivity on the thickness of the controlled laser etching has been revealed. The results are valuable for potential applications of 2D material devices built with complex layered structures.

Effect of scanning mode on temperature field and interface morphology of laser joining between CFRTP and TC4 titanium alloy

Dissimilar components composed of CFRTP (Carbon Fiber Reinforced Thermoplastic Polymer) and TC4 titanium alloy are increasingly applied in the aerospace field. The scanning mode offers a significant influence on the quality of laser joining joint between CFRTP and TC4 titanium alloy. Therefore, the laser joining between TC4 titanium alloy with surface microgrooves and CFRTP has been implemented under oscillating laser joining mode and linear laser joining mode respectively in the present research. The temperature distribution is qualitatively explored based on the established mathematical model of laser joining between CFRTP and TC4 titanium alloy. The interface morphology and the joining strength of CFRTP/TC4 titanium alloy lap joints under oscillating laser joining and linear laser joining are compared. The results indicate that the simulated temperature distribution shows good agreement with the experimental results. Compared with linear laser joining, the oscillating laser joining weakens the heat concentration and creates a heating zone with larger area and more uniform temperature distribution. The interface morphology of laser joining CFRTP/TC4 titanium alloy joints obtained by oscillating laser joining presents better resin filling and fewer bubble defects due to the temperature variation of the form of unequal amplitude oscillations, with the resin filling ratio of 92.20% and the porosity of 3.78%. In contrast, the linear laser scanning mode with a large number of large-sized bubbles in the filling resin and small-sized fusion gaps distributed at the interface holds a resin filling rate of 60.11% and a porosity of 32.89%. By adopting the joining method with oscillating laser scanning mode, higher quality joints can be obtained with the joining strength of 24.48 MPa.

Simulation of temperature distribution in forging of a workpiece with a single asperity

ABSTRACT Temperature distribution in a forging process influences the lubricant behaviour and die-wear. Non-uniform temperature distribution at the die-work interface results in the breakdown of lubrication film, which increases the heat generation due to increased friction. This work investigates the temperature distribution in the forging of a workpiece with a single asperity using the finite element (FE) simulations. Effects of asperity height in relation to workpiece, friction at die-work interface, percentage reduction and die velocity are studied. During the forging process, the temperature developed at the asperity region rises very rapidly. The asperity attains the maximum temperature after attaining its full height deformation. For the same deformation of workpiece, the temperature at asperity increases with an increase in the asperity height. The temperature at the asperity reduces with an increase in the friction at the die-work interface. The temperature at asperity as well as on the whole workpiece increases with increasing reduction. As heat dissipation from the workpiece surface is more at a relatively lower speed, the maximum temperature developed at asperity is greater at a higher speed. Insight provided by these simulations will assist in understanding the tribology of metal forming.

Simulation, Set-Up, and Thermal Characterization of a Water-Cooled Li-Ion Battery System

A constant and homogenous temperature control of Li-ion batteries is essential for a good performance, a safe operation, and a low aging rate. Especially when operating a battery with high loads in dense battery systems, a cooling system is required to keep the cell in a controlled temperature range. Therefore, an existing battery module is set up with a water-based liquid cooling system with aluminum cooling plates. A finite-element simulation is used to optimize the design and arrangement of the cooling plates regarding power consumption, cooling efficiency, and temperature homogeneity. The heat generation of an operating Li-ion battery is described by the lumped battery model, which is integrated into COMSOL Multiphysics. As the results show, a small set of non-destructively determined parameters of the lumped battery model is sufficient to estimate heat generation. The simulated temperature distribution within the battery pack confirmed adequate cooling and good temperature homogeneity as measured by an integrated temperature sensor array. Furthermore, the simulation reveals sufficient cooling of the batteries by using only one cooling plate per two pouch cells while continuously discharging at up to 3 C.

A Finite Element Analysis of the Effects of Preheating Substrate Temperature and Power Input on Selective Laser Melting

Several parameters are defined before the Selective Laser Melting printing process, which may depend on the manufacturer of the equipment, but in general, we commonly encounter hatch distance, scanning speed, layer thickness, laser power input, scanning strategy, overlap distance, and substrate preheating temperature as the parameters that mainly define the printing process. The last parameter is the focus of this study, which is applied to a finite element model to simulate temperature distributions over one layer thickness of the powder bed. The substrate temperature and power input affect the cooling rates and temperature gradients imposed on the powder bed, consequently influencing the component’s final property, surface finishing, and accuracy (dimensioning tolerances). The current FEM model showed that the preheat substrate temperature played different roles depending on which power input is used; however, there is an observed trend that is the reduction in temperature gradients in the powder bed overall when higher substrate temperatures are used.

Validating a simulation model for laser-induced thermotherapy using MR thermometry

Objectives We want to investigate whether temperature measurements obtained from MR thermometry are accurate and reliable enough to aid the development and validation of simulation models for Laser-induced interstitial thermotherapy (LITT). Methods Laser-induced interstitial thermotherapy (LITT) is applied to ex-vivo porcine livers. An artificial blood vessel is used to study the cooling effect of large blood vessels in proximity to the ablation zone. The experimental setting is simulated using a model based on partial differential equations (PDEs) for temperature, radiation, and tissue damage. The simulated temperature distributions are compared to temperature data obtained from MR thermometry. Results The overall agreement between measurement and simulation is good for two of our four test cases, while for the remaining cases drift problems with the thermometry data have been an issue. At higher temperatures local deviations between simulation and measurement occur in close proximity to the laser applicator and the vessel. This suggests that certain aspects of the model may need some refinement. Conclusion Thermometry data is well-suited for aiding the development of simulations models since it shows where refinements are necessary and enables the validation of such models.

Modeling and simulation of solvent behavior and temperature distribution within long stick propellants with large web thickness undergoing drying

Drying is a complicated physical process which involves simultaneous heat and mass transfer in the removal of solvents inside propellants. Inappropriate drying techniques may result in the formation of a hard skin layer near the surface to block the free access of most solvent through for long stick propellants with large web thickness, which lead to lower drying efficiency and worse drying quality. This study aims to gain a comprehensive understanding of drying process and clarify the mechanism of the blocked layer near the propellant surface. A new three-dimensional coupled heat and mass transfer (3D-CHMT) model was successfully developed under transient conditions. The drying experiment results show that the 3D-CHMT model could be applied to describe the drying process well since the relative error of the content of solvent between simulation and experiment values is only 5.5%. The solvent behavior simulation demonstrates that the mass transfer process can be divided into super-fast (SF) and subsequent minor-fast (MF) stages, and the SF stage is vital to the prevention of the blocked layer against the free access for solvent molecules inside propellant grains. The effective solvent diffusion coefficient (Deff) of the propellant surface initially increases from 3.4 × 10−6 to 5.3 × 10−6 m2/s as the temperature increases, and then decreases to 4.1 × 10−8 m2/s at 60–100 min. The value of Deff of surface between 0–1.4 mm has a unique trend of change compared with other regions, and it is much lower than that of the internal at 100 min under simulation conditions. Meanwhile, the temperature of the propellant surface increases rapidly at the SF stage (0–100 min) and then very slowly thereafter. Both the evolution of Deff and temperature distribution demonstrate that the blocked layer near the propellant surface has been formed in the time period of approximately 0–100 min and its thickness is about 1.4 mm. To mitigate the formation of blocked layer and improve its drying quality of finial propellant products effectively, it should be initially dried at lower drying temperature (30–40 °C) in 0–100 min and then dried at higher drying temperature (50–60 °C) to reduce drying time for later drying process in double base gun propellants. The present results can provide theoretical guidance for drying process and optimization of drying parameters for long stick propellants with large web thickness.

Microwave torrefaction of empty fruit bunch pellet: Simulation and validation of electric field and temperature distribution

Microwave simulation is significant in identifying a reactor design allowing the biomass to be heated and processed evenly. This study integrated the radio frequency and transient heat transfer modules to simulate the microwave distribution and investigated the performance of microwave heating in the cavity. The simulation results were compared with the experimental findings using the finite element analysis software of COMSOL MULTIPHYSICS to predict the temperature profile and electric field of microwave in the biomass (empty fruit bunch pellets). The higher temperature distribution was observed at the bottom and centre section of the empty fruit bunch pellet bed in the reactor, showing the uniqueness of microwave heating. According to the simulation results, the temperature profile obtained through the specific cavity geometry and dielectric properties agreed with the experimental temperature profile. The simulated temperature profile demonstrated a logarithmic increase of 120 °C/min at the first 50 s followed by 50 °C/min until 350 s. The experimental temperature profile showed three different heating rates before reaching 300 °C, including 78.3 °C/min (50–120 °C), 30.6 °C/min (121–250 °C), and 105 °C/min (250–300 °C). The results of this study might contribute to the improvement of microwave heating in biomass torrefaction.