scholarly journals Research on the Interrelation between Temperature Distribution and Dry Band on Wet Contaminated Insulators

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4289
Author(s):  
Da Zhang ◽  
Fancui Meng
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Relative Humidity ◽  
Moisture Absorption ◽  
Maximum Temperature ◽  
Water Evaporation ◽  
Thermal Imager ◽  
Insulator Surface ◽  
The Law ◽  
Dry Bands

In this paper, the interrelation between temperature distribution and dry band on wet contaminated insulators is studied by theoretical analysis, numerical simulation, and a high-voltage artificial contamination experiment. The influences of the composition of the contaminant and the relative humidity of the environment on the moisture absorption of the contamination layer are studied. It is indicated that the critical relative humidity (CRH) of the soluble mixture in the contamination layer decreases with the increase of the variety of soluble substances. This can be considered as a previously neglected reason for the inconsistency between the result of an artificial contamination test and that of a natural contamination test. Furthermore, the influences of the maximum temperature, wind speed, altitude, relative humidity, and the composition of the contamination on the water evaporation rate of the contaminated layer are also studied. The formation of dry band is predicted by studying the law of water transport in the contamination layer. The influence of the location, width, drying degree, and quantity of dry bands on the insulator surface temperature are studied by numerical simulation. An infrared thermal imager and ultraviolet camera are adopted to measure the temperature distribution and the discharge phenomenon on the insulator surface separately, which verifies the above numerical simulation. The study results deepen the research on the moisture absorption characteristics, the law of temperature distribution, the formation of dry bands, and the influence of dry bands on the temperature distribution of wet contaminated insulators.

Numerical Simulation of Temperature Field in the Cyclone

2012 ◽  
Vol 614-615 ◽  
pp. 208-211
Author(s):  
Zhen Wei Zhang ◽  
Ying Yu ◽  
Jie Leng ◽  
Su Juan Zhang
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Turbulence Model ◽  
Temperature Difference ◽  
Minimum Temperature ◽  
Maximum Temperature ◽  
Inlet Tube ◽  
Higher Temperature ◽  
Air Compression

The temperature distribution of the cyclone was analyzed in the presented work, which was imitated by using RSM turbulence model of software FLUENT. Temperature difference in different regions is less than one centigrade degree with the maximum temperature in the cone part and the minimum temperature in inlet tube and cylinder part of the cyclone, what’s more, the temperature is relatively higher near the wall. The air compression can lead the higher temperature in the lower part, so the cone part has the maximum temperature. The higher temperature near the wall is caused by the friction between the wall and flow.

Accurate Predetermination of the Process Parameters for Glass/Glass Laser Bonding Based on the Temperature Distribution Analysis

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Yanyi Xiao ◽  
Wen Wang ◽  
Jianhua Zhang
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Thermal Imager ◽  
Distribution Analysis ◽  
Analysis Model ◽  
Glass Laser ◽  
Element Analysis ◽  
Laser Bonding

Temperature distribution is the key factor affecting the bonding quality in the glass/glass laser bonding process. In this work, the finite element method was used to establish three-dimensional (3D) numerical analysis model of the temperature field during bonding. Based on the result of the finite element analysis, the crucial parameters and their influences on the temperature distribution were discussed. In order to predetermine the necessary process parameter values for bonding, a nonlinear multiparameter fitting formula was established to predict the maximum temperature. The fitting model was validated experimentally by recording the maximum temperature during laser bonding via an infrared thermal imager.

Numerical Simulation of Temperature Field in the Cyclone

2012 ◽  
Vol 479-481 ◽  
pp. 462-466
Author(s):  
Ping Yang Xiao ◽  
Zhen Wei Zhang
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Turbulence Model ◽  
Temperature Difference ◽  
Minimum Temperature ◽  
Maximum Temperature ◽  
Inlet Tube ◽  
Higher Temperature ◽  
Air Compression

This paper mainly focuses on the numerical simulation of temperature field in the cyclone separation. The authors took advantage of RSM turbulence model of software FLUENT to imitate the temperature field. This thesis puts forward the temperature distribution of the cyclone, and figures out that the overall temperature is 373°C. Temperature difference in different region is less than one centigrade degree with the maximum temperature in the cone part and the minimum temperature in inlet tube and cylinder part of the cyclone, what’s more, the temperature is relatively higher near the wall. The air compression can lead the higher temperature in the lower part, so the cone part has the highest temperature. The higher temperature near the wall is caused by the friction between the wall and flow.

Numerical Simulation on the Influence of Heating with Different Arrangement of Burners on the High Performance Hydrogen Bell-Type Annealers

2011 ◽  
Vol 402 ◽  
pp. 374-379
Author(s):  
Shun Li Fang ◽  
Shi Ping Jin ◽  
Yong Xiang Zhang ◽  
Su Yi Huang ◽  
Wu Qi Wen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Temperature Distribution ◽  
High Performance ◽  
Heating Power ◽  
Maximum Temperature ◽  
Heating Process ◽  
Heating Effect ◽  
Reduce Fuel Consumption ◽  
Heating Device

The heating bell with burners is an important heating device for the high performance hydrogen bell-type annealers. The arrangement of the burners has an important impact on the heating effect. In this study, we simulated a series of model with different location of burners under the same quantity of burners and the same heating power. The result shows: (1) Under the same quantity of burners and the same heating power, when we increase the number of rows of burners, the maximum temperature inside the furnace could be reduced, and the temperature distribution will become more uniform; (2)When we fixed the number of the row of the burners, if we move the upper burners to higher position to make the arrangement of burners more uniform, the temperature distribution inside the furnace will be more uniform, this will be good for the heat transfer to the higher parts of the annealers, and this will accelerate the heating process, improve the efficiency of annealing, reduce fuel consumption, and extend the life of the inner bell.

The Thermo-Hydrodynamic Analysis of the Plain Journal Bearing With Centered Circumferential Groove: Numerical Simulation vs. Experiment

2020 ◽  
Author(s):  
Guanghui Zhang ◽  
Shubo Yu ◽  
Zhansheng Liu ◽  
Kefan Xu ◽  
Yu Li
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Journal Bearing ◽  
Groove Width ◽  
Lubricating Oil ◽  
Maximum Temperature ◽  
Clearance Ratio ◽  
Hydrodynamic Analysis ◽  
Circumferential Groove ◽  
Bearing Clearance

Abstract In order to increase the reliability of the oil lubricated journal bearing, the thermal characteristics of the plain journal bearing are investigated and optimized. In this paper, the steady state thermo-hydrodynamic analysis of the plain journal bearing with centered circumferential groove is studied by numerical simulation and experiments. The diameter of the journal bearing is 190mm, and the load of the bearing is 6150N, which is operated with the rotating speed of 5560 r/min. The flow characteristics including the temperature distribution in the clearance of the bearing are simulated by ANSYS CFX, where the Walther viscosity temperature relation and the cavitation effect are considered. The test rig for measuring the pressure and temperature distributing in established, which is driven by electrical motor and certain bearing load can be exerted on it. In the experiments, the temperature distribution of the bearing is measured by 10 temperature sensors, which is arranged on three cross sections along the axial direction. The temperature of the lubricating oil is obtained by the sensors on the shell of the bearing, which is installed in the Babbitt metal. In order to obtain the circumferential distribution of the temperature, the sensors locate at different circumferential angles. The influence of geometrical parameters on the temperature distribution is studied, including the bearing clearance, the bearing length and the groove width by numerical simulation and experiment. The bearing clearance ratios of 1.8‰ and 2.5‰ are compared, and as the increment of the bearing clearance ratio, the temperature of the bearing decreased, which is benefit from the flow mass into the bearing increases. For the bearing length increasing from 90mm to 94mm, the maximum temperature decreases about 3K. For the groove width varying from 20mm to 19mm and 18mm, the temperature of the bearing decreases. The comparison of the numerical results and experiments are presented, and they show similar tendency for the temperature distribution, but the difference of temperature values exists. Based on the results from variation of bearing clearance ratio, bearing length and groove width, the optimized parameters of the bearing are proposed by determining the groove width with 18mm, bearing length with 94mm and the bearing clearance ratio with 2.1‰. The thermo-hydrodynamic analysis from the CFD and the experiments for the optimized bearing are carried out. The results indicate that the thermal performance of the bearing is improved. Compared with original design of the bearing, the maximum temperature is reduced by approximately 5K for optimized design of the bearing.

scholarly journals Non-Uniform Temperature Field of Spatial Grid Structure under Construction Induced by Solar Radiation

2020 ◽  
Vol 10 (7) ◽  
pp. 2445
Author(s):  
Deshen Chen ◽  
Hongliang Qian ◽  
Huajie Wang ◽  
Wucheng Xu ◽  
Jingfang Li
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Solar Radiation ◽  
Test Data ◽  
Maximum Temperature ◽  
Uniform Temperature ◽  
Grid Structure ◽  
Spatial Grid ◽  
Under Construction

The temperature of spatial structures under construction can have a significant non-uniform distribution induced by intense solar radiation. This temperature distribution affects the component assembly and results in closure difficulties, potentially causing safety hazards. A spatial grid structure model was designed and subjected to temperature field test under sunlight to study the temperature distribution of the structure and for comparison with numerical simulation methods. The distribution characteristics and the time-varying laws were analyzed based on the test data. Then, the ray-casting algorithm was introduced to analyze the shadow influence between members, so that the temperature distribution of the model was simulated accurately, which was verified by the test data. The results show that the spatial grid structure had an obvious non-uniform temperature distribution, with a maximum temperature rise of 16 °C when compared with ambient temperature and a maximum temperature difference between members of 11 °C. The variation laws were gained both from the test and the numerical simulation. The numerical simulation method proposed herein can be used to calculate the shadow distribution and the temperature field of the structure effectively. The research methods and conclusions can provide valuable references for thermal design, monitoring, and control of spatial grid structures.

scholarly journals Transient temperature distribution on the corneal endothelium during ophthalmic phacoemulsification: a numerical simulation using the nodeless variable element

2010 ◽  
Vol 4 (6) ◽  
pp. 885-892 ◽  
Author(s):  
Wiroj Limtrakarn ◽  
Somporn Reepolmaha ◽  
Pramote Dechaumphai
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Anterior Chamber ◽  
Heat Generation ◽  
Corneal Endothelium ◽  
Temperature Response ◽  
Maximum Temperature ◽  
Transient Temperature ◽  
Cataract Operation ◽  
Transient Temperature Distribution

Abstract Background: During cataract operation (phacoemulsification), a phaco needle-tip is inserted into the anterior chamber of eye. Then, heat is generated by the oscillation of the phaco needle, which may injury the corneal endothelial cells. There are no data available for temperature responses at the corneal endothelium to heat from the phaco needle during phacoemulsification. Objective: Investigate temperature distribution on the corneal endothelium during ophthalmic phacoemulsification using numerical simulation, and compare the transient temperature response to heat between balanced salt solution (BSS) and ophthalmic viscoelastic device (OVD), Viscoat®. Methods: Heat flux from a phaco needle was measured with thermal properties of BSS and AVS in an experimental setting. Then, nodeless variable finite element method was applied to predict temperature changes in the eye by the phaco needle inserted into the anterior chamber. The transient temperature distribution on the corneal endothelium was calculated at 10, 20, and 30 seconds after heat generation by the needle. Results: The heat generation of phaco needle without sleeve cover was 1.6 kW/m2. The numerical simulation showed that the maximum temperature occurs on the wound location at all times after heat generation by the phaco needle. Especially, at time 30 seconds, it was 49.2 and 41.7°C in BSS and OVD, respectively. The temperature elevation by the phaco needle was lower in OVD than BSS. Conclusion: Phacoemulsification is a heat-generating procedure performed between the anterior chamber structures of eye. During this procedure, OVD may protect the corneal endothelium against heat better than BSS.

scholarly journals The Influence of Meshing Strategies on The Numerical Simulation of Solar Greenhouse Dryer

2021 ◽  
Vol 947 (1) ◽  
pp. 012007
Author(s):  
Viet. T. Tran ◽  
Yen. H.P. Duong ◽  
Tan M. Le
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Relative Humidity ◽  
Mesh Generation ◽  
Optimum Conditions ◽  
Ansys Fluent ◽  
Solar Greenhouse ◽  
Hexahedral Meshing ◽  
Fluent Software ◽  
Tetrahedral Meshing

Abstract In the present study, we conduct the numerical simulation for solar greenhouse dryer performance by Ansys Fluent software. The numerical simulations compared the meshing strategies for the dryer and show the effects on both temperature distribution and relative humidity distribution of air inside the dryer. Unstructured meshes were used in the numerical simulation employing hexahedral meshing and tetrahedral meshing for mesh generation. The meshing strategies were evaluated through 2 size of cell i.e., 0.1 m and 0.05m. The results indicated that the size of cell have strong effect than the mesh type on the temperature profile and humidity of air inside the dryer. Thus, the results gave the engineers more options to select the optimum conditions for meshing and simulation the dryer.

Numerical Simulation of Leakage Current on Conductive Insulator Surface

2019 ◽  
Vol 8 (4) ◽  
pp. 9487-9492
Keyword(s):  
Numerical Simulation ◽  
Electric Field ◽  
Leakage Current ◽  
Method Of Lines ◽  
Electron Attachment ◽  
Negative Ions ◽  
Conduction Current ◽  
Insulator Surface ◽  
Finite Difference Approximations ◽  
Positive Ions

The outdoor insulator is commonly exposed to environmental pollution. The presence of water like raindrops and dew on the contaminant surface can lead to surface degradation due to leakage current. However, the physical process of this phenomenon is not well understood. Hence, in this study we develop a mathematical model of leakage current on the outdoor insulator surface using the Nernst Planck theory which accounts for the charge transport between the electrodes (negative and positive electrode) and charge generation mechanism. Meanwhile the electric field obeys Poisson’s equation. Method of Lines technique is used to solve the model numerically in which it converts the PDE into a system of ODEs by Finite Difference Approximations. The numerical simulation compares reasonably well with the experimental conduction current. The findings from the simulation shows that the conduction current is affected by the electric field distribution and charge concentration. The rise of the conduction current is due to the distribution of positive ion while the dominancy of electron attachment with neutral molecule and recombination with positive ions has caused a significant reduction of electron and increment of negative ions.

scholarly journals Experimental Study on Infrared Temperature Characteristics and Failure Modes of Marble with Prefabricated Holes under Uniaxial Compression

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 713
Author(s):  
Yanyan Peng ◽  
Qunchao Lin ◽  
Manchao He ◽  
Chun Zhu ◽  
Haijiang Zhang ◽  
...  
Keyword(s):  
Uniaxial Compression ◽  
Failure Modes ◽  
Rock Sample ◽  
Vertical Axis ◽  
Maximum Temperature ◽  
Thermal Imager ◽  
Infrared Thermal Imaging ◽  
Average Temperature ◽  
Observation Area ◽  
Evolution Behavior

In rock engineering, it is of great significance to study the failure mechanical behavior of rocks with holes. Using a combination of experiment and infrared detection, the strength, deformation, and infrared temperature evolution behavior of marble with elliptical holes under uniaxial compression were studied. The test results showed that as the vertical axis b of the ellipse increased, the peak intensity first decreased and then increased, and the minimum value appeared when the horizontal axis was equal to the vertical axis. The detection results of the infrared thermal imager showed that the maximum temperature, minimum temperature, and average temperature of the observation area in the loading stage showed a downward trend, and the range of change was between 0.02 °C and 1 °C. It was mainly due to the accumulation of energy in the loading process of the rock sample that caused the surface temperature of the specimen to decrease. In the brittle failure stage, macroscopic cracks appeared on the surface of the rock sample, which caused the energy accumulated inside to dissipate, thereby increasing the maximum temperature and average temperature of the rock sample. The average temperature increase was about 0.05 °C to about 0.19 °C. The evolution of infrared temperature was consistent with the mechanical characteristics of rock sample failure, indicating that infrared thermal imaging technology can provide effective monitoring for the study of rock mechanics. The research in this paper provides new ideas for further research on the basic characteristics of rock failure under uniaxial compression.

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