This study, while reviewing some of the established unified equations and fundamentals of the energy structure and providing a detailed interpretation of their physical concepts, expands the relevant equations for new topics and applications, and in fact, establishes novel results and equations from the energy structure analysis. In fact, this paper establishes an energy components-based-general model inspired by the first and second laws of thermodynamics as well as using a new division to the total energy of the system. The established model is completed by extracting the physical direction for the feasible processes based on the energy components of the system. As two of the most important achievements of the energy components approach, using a new quasi-statistical approach as well as a novel energy conservation principle, an entropy equation is gained that has a common basis as the Boltzmann entropy equation as well as a general solution to the different formulations of the second law of thermodynamics is established. The established equations are gained without any limiting assumptions, and are governed to any physical system. Several basic examples have been studied, and matching the obtained results with expected ones is shown.
{"title":"Energy Structure Theory: A General Unified Thermodynamics Theory","authors":"Saeed Shahsavari, S. Boutorabi","doi":"10.5541/ijot.1257725","DOIUrl":"https://doi.org/10.5541/ijot.1257725","url":null,"abstract":"This study, while reviewing some of the established unified equations and fundamentals of the energy structure and providing a detailed interpretation of their physical concepts, expands the relevant equations for new topics and applications, and in fact, establishes novel results and equations from the energy structure analysis. In fact, this paper establishes an energy components-based-general model inspired by the first and second laws of thermodynamics as well as using a new division to the total energy of the system. The established model is completed by extracting the physical direction for the feasible processes based on the energy components of the system. As two of the most important achievements of the energy components approach, using a new quasi-statistical approach as well as a novel energy conservation principle, an entropy equation is gained that has a common basis as the Boltzmann entropy equation as well as a general solution to the different formulations of the second law of thermodynamics is established. The established equations are gained without any limiting assumptions, and are governed to any physical system. Several basic examples have been studied, and matching the obtained results with expected ones is shown.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41989193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In recent years tomatoes have been peeled using steam and lye. Both are costlier, less environmentally friendly and highly polluting techniques. Thus, more sustainable alternatives should be sought after. Among these alternatives is radiative heating. To appropriately design the system for dry peeling, several typical operational characteristics of the process in issue must be estimated. The analytical model presented allows estimates to be made through closed-form relationships between the parameters involved. The analysis is based on the use of an appropriate theoretical model, which facilitates the solution to the proposed problems. Through the approximate solution of the analytical problem, we will analyse: the angular speed Ω, the temperature fluctuations ΔT0, the process time tc. These estimates are then used to derive a specific model for a control of process. The temperature profile (through an approximate solution) associated with the process that provides the optimum peel quality was utilized as a guide for the regulation system. A control system used the code to extract a specific temperature, and based on surface tomato temperature readings, controlled a brushless motor using a logic strategy. The regulating system can adjust the rotation speed, and hence the heating intensity, even under less than perfect operating conditions in order to obtain the appropriate profile temperature. The controlled temperature profile yielded an average temperature of 66.3°C, while the reference case yielded a temperature of 67°C. Additionally, it was found that the temperature inaccuracy decreased with each rotation, ranging from 2.5 °C at 2π to 0.3 °C at 16π. As a result, the peeling procedure is standardized in time, temperature, and quality.
{"title":"Optimization of a Dry Peeling System for Tomatoes Using Approximate Solutions","authors":"A. Metallo","doi":"10.5541/ijot.1225294","DOIUrl":"https://doi.org/10.5541/ijot.1225294","url":null,"abstract":"In recent years tomatoes have been peeled using steam and lye. Both are costlier, less environmentally friendly and highly polluting techniques. Thus, more sustainable alternatives should be sought after. Among these alternatives is radiative heating. To appropriately design the system for dry peeling, several typical operational characteristics of the process in issue must be estimated. The analytical model presented allows estimates to be made through closed-form relationships between the parameters involved. The analysis is based on the use of an appropriate theoretical model, which facilitates the solution to the proposed problems. Through the approximate solution of the analytical problem, we will analyse: the angular speed Ω, the temperature fluctuations ΔT0, the process time tc. These estimates are then used to derive a specific model for a control of process. The temperature profile (through an approximate solution) associated with the process that provides the optimum peel quality was utilized as a guide for the regulation system. A control system used the code to extract a specific temperature, and based on surface tomato temperature readings, controlled a brushless motor using a logic strategy. The regulating system can adjust the rotation speed, and hence the heating intensity, even under less than perfect operating conditions in order to obtain the appropriate profile temperature. The controlled temperature profile yielded an average temperature of 66.3°C, while the reference case yielded a temperature of 67°C. Additionally, it was found that the temperature inaccuracy decreased with each rotation, ranging from 2.5 °C at 2π to 0.3 °C at 16π. As a result, the peeling procedure is standardized in time, temperature, and quality.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45211741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Different types of thermometers (resistance thermometers, thermocouples, liquid in glass thermometers, radiation thermometers, etc.) are used in temperature measurements. Resistance thermometers are among the most reliable types of sensors used for sensitive temperature measurements. The traceability, accuracy and precision of the measurement results are important for the reliability of the measurements. There are many parameters that affect the uncertainty estimation in measurements made with resistance thermometers. One of the parameters to be considered in the uncertainty estimation is the interpolation error in converting the resistance value to temperature. Different methods (ITS-90, Calendar Van Dusen CVD, Polynomial equation) can be used to convert the resistance value to temperature. The problem is that there are differences in the temperature values read using the coefficients obtained by different methods. In this study, the effect of errors from CVD and polynomial equation methods on measurement uncertainty was investigated.
温度测量中使用不同类型的温度计（电阻温度计、热电偶、玻璃中液体温度计、辐射温度计等）。电阻温度计是用于敏感温度测量的最可靠的传感器类型之一。测量结果的可追溯性、准确性和精密度对测量的可靠性至关重要。在电阻温度计的测量中，有许多参数会影响不确定度的估计。不确定性估计中要考虑的参数之一是将电阻值转换为温度时的插值误差。可以使用不同的方法（ITS-90、Calendar Van Dusen CVD、多项式方程）将电阻值转换为温度。问题在于，使用通过不同方法获得的系数读取的温度值存在差异。在本研究中，研究了CVD和多项式方程方法的误差对测量不确定度的影响。
{"title":"The Effect of the Conversion Coefficients of Platinum-Based Resistance Thermometers on the Uncertainty Estimation","authors":"F.M. Patan Alper","doi":"10.5541/ijot.1220322","DOIUrl":"https://doi.org/10.5541/ijot.1220322","url":null,"abstract":"Different types of thermometers (resistance thermometers, thermocouples, liquid in glass thermometers, radiation thermometers, etc.) are used in temperature measurements. Resistance thermometers are among the most reliable types of sensors used for sensitive temperature measurements. The traceability, accuracy and precision of the measurement results are important for the reliability of the measurements. There are many parameters that affect the uncertainty estimation in measurements made with resistance thermometers. One of the parameters to be considered in the uncertainty estimation is the interpolation error in converting the resistance value to temperature. Different methods (ITS-90, Calendar Van Dusen CVD, Polynomial equation) can be used to convert the resistance value to temperature. The problem is that there are differences in the temperature values read using the coefficients obtained by different methods. In this study, the effect of errors from CVD and polynomial equation methods on measurement uncertainty was investigated.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42144735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The presence of both critical and azeotropic states in the vapor-liquid equilibria (VLE) is a very important issue in the chemical and refrigeration engineering. The knowledge of the phase behavior (subcritical phase/supercritical phase) of refrigerant allows designing and optimizing the refrigeration industrials processes. However, it is rare to find data for this information, which poses a great challenge for researchers to develop predictive and correlative thermodynamic models. The present study proposes the computation of the compositions and pressures of critical and azeotropic points of the isothermal VLE as well as the correlation of experimental VLE data. Firstly, experimental data (PTxy) was used to predict the vapor-liquid phase of both critical and azeotropic behaviors and to determine their properties using the relative volatility model. Secondly, the thermodynamic model (PR-MC-WS-NRTL) was applied to correlate the data of the binary refrigerant systems and describe their isothermal (VLE) behavior. The results proved that there is good agreement between predicted values obtained by the developed model and the experimental reference data. The relative error of both critical and azeotropic properties does not exceed 4.3 % for the molar fraction and 7.5 % for the pressure using relative volatility model. On other hand the relative deviation is respectively less than 2.60 % and 2.58 % for the liquid and vapor mole fractions using (PR-MC-WS-NRTL) model. This shows the ability of these models to give a reliable solution to predict and modulate the phase behavior of the binary refrigerant systems.
{"title":"Modeling of the Vapor-Liquid Equilibria Properties of Binary Mixtures for Refrigeration Machinery","authors":"Youcef Maalem, Youcef Tamene, H. Madani","doi":"10.5541/ijot.1140088","DOIUrl":"https://doi.org/10.5541/ijot.1140088","url":null,"abstract":"The presence of both critical and azeotropic states in the vapor-liquid equilibria (VLE) is a very important issue in the chemical and refrigeration engineering. The knowledge of the phase behavior (subcritical phase/supercritical phase) of refrigerant allows designing and optimizing the refrigeration industrials processes. However, it is rare to find data for this information, which poses a great challenge for researchers to develop predictive and correlative thermodynamic models. The present study proposes the computation of the compositions and pressures of critical and azeotropic points of the isothermal VLE as well as the correlation of experimental VLE data. Firstly, experimental data (PTxy) was used to predict the vapor-liquid phase of both critical and azeotropic behaviors and to determine their properties using the relative volatility model. Secondly, the thermodynamic model (PR-MC-WS-NRTL) was applied to correlate the data of the binary refrigerant systems and describe their isothermal (VLE) behavior. The results proved that there is good agreement between predicted values obtained by the developed model and the experimental reference data. The relative error of both critical and azeotropic properties does not exceed 4.3 % for the molar fraction and 7.5 % for the pressure using relative volatility model. On other hand the relative deviation is respectively less than 2.60 % and 2.58 % for the liquid and vapor mole fractions using (PR-MC-WS-NRTL) model. This shows the ability of these models to give a reliable solution to predict and modulate the phase behavior of the binary refrigerant systems.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45608215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A fractional Cattaneo model for studying the thermoelastic response for a finite thick circular plate with source function is considered. The thick plate is subjected to radiation-type boundary conditions on the upper and lower surfaces, and its curved surface is kept at zero temperature. The theory of integral transformations is used to solve the generalized fractional Cattaneo-type, classical Cattaneo-Vernotte and Fourier heat conduction model. The analytical expressions of displacement components using thermoelastic displacement potentials; and thermal-stress distribution are computed and depicted graphically. The effects of the fractional-order parameter and the relaxation time on the temperature fields and their thermal stresses are investigated. The findings show that the higher the fractional-order parameter, the higher the thermal response. The greater the relaxation period, the longer the heat flux propagates on thick structures.
{"title":"Thermoelastic Analysis For A Thick Plate Under The Radiation Boundary Conditions","authors":"G. Dhameja, L. Khalsa, V Varghese","doi":"10.5541/ijot.1170342","DOIUrl":"https://doi.org/10.5541/ijot.1170342","url":null,"abstract":"A fractional Cattaneo model for studying the thermoelastic response for a finite thick circular plate with source function is considered. The thick plate is subjected to radiation-type boundary conditions on the upper and lower surfaces, and its curved surface is kept at zero temperature. The theory of integral transformations is used to solve the generalized fractional Cattaneo-type, classical Cattaneo-Vernotte and Fourier heat conduction model. The analytical expressions of displacement components using thermoelastic displacement potentials; and thermal-stress distribution are computed and depicted graphically. The effects of the fractional-order parameter and the relaxation time on the temperature fields and their thermal stresses are investigated. The findings show that the higher the fractional-order parameter, the higher the thermal response. The greater the relaxation period, the longer the heat flux propagates on thick structures.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47142281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fuel consumption optimization in thermal power plants is one of the essential topics in the saving energy field in the world. Then; it is necessary to review and provide solutions to increase efficiency. The present manuscript has recovered the heat dissipation from power plant stacks. The Kalina cycle was studied to use exhaust gases to generate power in the Tarasht power plant. Net power output is calculated at about 2080 kW, which increases the total power production of the plant by about 5%. According to environmental analysis, this cycle will cause less damage to the environment due to lowering the temperature of the exhaust gases in the atmosphere and not using additional fossil fuels. Therefore; it is a good solution for using heat dissipation from power plants. The only thing to consider in this solution (based on economic analysis) is the high construction cost compared to other power plant units.
{"title":"Investigation of Kalina Cycle for Power Generation from Heat Dissipation of Tarasht Power Plant","authors":"S. Sadri, Seyed Yousef SEYED MOHSENİ","doi":"10.5541/ijot.1214617","DOIUrl":"https://doi.org/10.5541/ijot.1214617","url":null,"abstract":"Fuel consumption optimization in thermal power plants is one of the essential topics in the saving energy field in the world. Then; it is necessary to review and provide solutions to increase efficiency. The present manuscript has recovered the heat dissipation from power plant stacks. The Kalina cycle was studied to use exhaust gases to generate power in the Tarasht power plant. Net power output is calculated at about 2080 kW, which increases the total power production of the plant by about 5%. According to environmental analysis, this cycle will cause less damage to the environment due to lowering the temperature of the exhaust gases in the atmosphere and not using additional fossil fuels. Therefore; it is a good solution for using heat dissipation from power plants. The only thing to consider in this solution (based on economic analysis) is the high construction cost compared to other power plant units.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46571942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The increase in global energy demand has directed researchers towards making low-quality coals into an environmentally friendly energy source by reducing their high moisture content. Drying coal is a high-energy and time-consuming process, so reducing the required energy and drying time is crucial for drying technology. Coal drying increases the thermal value of coal and makes it easier to transport. In this study, a coal drying system was designed using waste heat recovery systems, R-134a refrigerant as working fluid, air source heat pumps, and vacuum tube solar collectors to provide hot air. Firstly, the moisture content of the coal and the desired moisture content after drying were determined, and then the heat required to dry the coal was calculated. Next, the capacity of the solar collector required to provide the necessary heat to the heat pump was determined, and the type and capacity of the heat pump that could produce the required heat were selected. Finally, the coal dryer was designed based on the specific requirements of the power plant and the type of coal used. As a result, the coal drying system designed with solar-assisted heat pumps and waste heat utilization can increase the efficiency of coal-fired power plants by reducing the moisture content of coal before combustion.
{"title":"Design of a Coal Drying System with Solar-Assisted Heat Pump and Waste Heat Utilisation","authors":"M. Ökten","doi":"10.5541/ijot.1219737","DOIUrl":"https://doi.org/10.5541/ijot.1219737","url":null,"abstract":"The increase in global energy demand has directed researchers towards making low-quality coals into an environmentally friendly energy source by reducing their high moisture content. Drying coal is a high-energy and time-consuming process, so reducing the required energy and drying time is crucial for drying technology. Coal drying increases the thermal value of coal and makes it easier to transport. In this study, a coal drying system was designed using waste heat recovery systems, R-134a refrigerant as working fluid, air source heat pumps, and vacuum tube solar collectors to provide hot air. Firstly, the moisture content of the coal and the desired moisture content after drying were determined, and then the heat required to dry the coal was calculated. Next, the capacity of the solar collector required to provide the necessary heat to the heat pump was determined, and the type and capacity of the heat pump that could produce the required heat were selected. Finally, the coal dryer was designed based on the specific requirements of the power plant and the type of coal used. As a result, the coal drying system designed with solar-assisted heat pumps and waste heat utilization can increase the efficiency of coal-fired power plants by reducing the moisture content of coal before combustion.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45328830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper considers a transient thermoelastic problem in an isotropic homogeneous elastic thin circular plate with clamped edges subjected to thermal load within the fractional-order theory framework. The prescribed ramp-type surface temperature is on the plate's top face, while the bottom face is kept at zero. The three-dimensional heat conduction equation is solved using a Laplace transformation and the classical solution method. The Gaver–Stehfest approach was used to invert Laplace domain outcomes. The thermal moment is derived based on temperature change, and its bending stresses are obtained using the resultant moment and resultant forces per unit length. The results are illustrated by numerical calculations considering the material to be an Aluminum-like medium, and corresponding graphs are plotted.
{"title":"Thermally-Induced Stresses in a Pre-Buckling State of a Circular Plate within the Fractional-Order Framework","authors":"G. Dhameja, L. Khalsa, V Varghese","doi":"10.5541/ijot.1170364","DOIUrl":"https://doi.org/10.5541/ijot.1170364","url":null,"abstract":"This paper considers a transient thermoelastic problem in an isotropic homogeneous elastic thin circular plate with clamped edges subjected to thermal load within the fractional-order theory framework. The prescribed ramp-type surface temperature is on the plate's top face, while the bottom face is kept at zero. The three-dimensional heat conduction equation is solved using a Laplace transformation and the classical solution method. The Gaver–Stehfest approach was used to invert Laplace domain outcomes. The thermal moment is derived based on temperature change, and its bending stresses are obtained using the resultant moment and resultant forces per unit length. The results are illustrated by numerical calculations considering the material to be an Aluminum-like medium, and corresponding graphs are plotted.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48850508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The electrical energy needs grow every year, increasing awareness and use of renewable energy even higher. Geothermal power plants (GPP) are even ogled as a renewable energy source that has a lot of potential worldwide. Technology for GPP continues to evolve. However, tools for analyzing a system of GPP are still inadequate. In this study, a simple analysis tool was designed. The usefulness of this analysis tool is to be able to know the state of the GPP works. This tool will help simulate the conditions that may occur in the plant system. The simulation results will also be known operating conditions that may occur, so the operator can determine what should be done if things happen. Modeling started using Microsoft Excel, which has been equipped with thermodynamic properties. Modeling includes turbine, condenser, cooling tower, and extraction systems non-condensable gas. After validated, the model run simulation in variations that may occur such as decline in the condition of the condenser and cooling tower and environmental conditions, represented by relative humidity. The simulation with variation of condition will decrease the power generated from turbine 3 – 5%.
{"title":"Modelling and Simulation of Existing Geothermal Power Plant: A Case Study of Darajat Geothermal Power Plant","authors":"K. F. A. Sukra, D. Permana, W. Adriansyah","doi":"10.5541/ijot.1118778","DOIUrl":"https://doi.org/10.5541/ijot.1118778","url":null,"abstract":"The electrical energy needs grow every year, increasing awareness and use of renewable energy even higher. Geothermal power plants (GPP) are even ogled as a renewable energy source that has a lot of potential worldwide. Technology for GPP continues to evolve. However, tools for analyzing a system of GPP are still inadequate. In this study, a simple analysis tool was designed. The usefulness of this analysis tool is to be able to know the state of the GPP works. This tool will help simulate the conditions that may occur in the plant system. The simulation results will also be known operating conditions that may occur, so the operator can determine what should be done if things happen. Modeling started using Microsoft Excel, which has been equipped with thermodynamic properties. Modeling includes turbine, condenser, cooling tower, and extraction systems non-condensable gas. After validated, the model run simulation in variations that may occur such as decline in the condition of the condenser and cooling tower and environmental conditions, represented by relative humidity. The simulation with variation of condition will decrease the power generated from turbine 3 – 5%.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48873377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The weld quality is highly related to the thermal history of the weld and there have been many trials to monitor the quality using an infrared (IR) sensor. To obtain the real temperature of a surface based on the brightness temperature values measured by an IR camera, the emissivity value must be derived. For an accurate assessment of the emissivity, one must be aware of the melting point isotherm. The temperature profiles only depend on three factors during laser processing, specified as constants the characteristics of the material: laser beam speed (v), laser beam diameter (d), and power (P). Predicting the width of the melted zone reached during the welding process as the parameters vary is a tool for helping a quality laser processing and for determination of true temperature in laser welding using IR camera. This study describes the semi-analytical (SA) solution of the heat conduction equation for a localized moving Gaussian heat source with constant parameters on a semi-infinite medium. The solution, simple and quick to obtain, provides information on the width of the melted zone with an average error < 5 %. The outcome is assessed numerically and contrasted with FEM solutions for a Gaussian source, the latter having undergone experimental validation. With two distinct defocus values, def0 and def-6, and by varying the speed and power settings, two separate types of experiments were run. Thus, the SA solution was obtained and compared after the FEM solution had been obtained with a good approximation (max err 4.3 %, average err 2.7 %). Only in regard to the 1AL test is an error more than 5 % detected; in the other case, the average error is 3.75 %. Two more tests at the defocus values of def-4 and def-8 were conducted to confirm the model's validity as the parameters varied. Overall, the average error between the semi-analytical and the FEM solution is 4.1%. The SA solution may be used to effectively estimate the isotherms related to the melting point of aluminum (770 K). This allows to obtain a tool which helps restoring the real temperature based on the brightness values measured by the IR camera during laser welding. At the same time, this effective tool allows to investigate the importance of different processing parameters in laser manufacturing.
{"title":"Semi-Analytical Solution for Modelling Moving Heat Sources in a Semi-Infinite Medium with Radiative and Convective Boundary Conditions","authors":"A. Metallo","doi":"10.5541/ijot.1097756","DOIUrl":"https://doi.org/10.5541/ijot.1097756","url":null,"abstract":"The weld quality is highly related to the thermal history of the weld and there have been many trials to monitor the quality using an infrared (IR) sensor. To obtain the real temperature of a surface based on the brightness temperature values measured by an IR camera, the emissivity value must be derived. For an accurate assessment of the emissivity, one must be aware of the melting point isotherm. The temperature profiles only depend on three factors during laser processing, specified as constants the characteristics of the material: laser beam speed (v), laser beam diameter (d), and power (P). Predicting the width of the melted zone reached during the welding process as the parameters vary is a tool for helping a quality laser processing and for determination of true temperature in laser welding using IR camera. This study describes the semi-analytical (SA) solution of the heat conduction equation for a localized moving Gaussian heat source with constant parameters on a semi-infinite medium. The solution, simple and quick to obtain, provides information on the width of the melted zone with an average error < 5 %. The outcome is assessed numerically and contrasted with FEM solutions for a Gaussian source, the latter having undergone experimental validation. With two distinct defocus values, def0 and def-6, and by varying the speed and power settings, two separate types of experiments were run. Thus, the SA solution was obtained and compared after the FEM solution had been obtained with a good approximation (max err 4.3 %, average err 2.7 %). Only in regard to the 1AL test is an error more than 5 % detected; in the other case, the average error is 3.75 %. Two more tests at the defocus values of def-4 and def-8 were conducted to confirm the model's validity as the parameters varied. Overall, the average error between the semi-analytical and the FEM solution is 4.1%. The SA solution may be used to effectively estimate the isotherms related to the melting point of aluminum (770 K). This allows to obtain a tool which helps restoring the real temperature based on the brightness values measured by the IR camera during laser welding. At the same time, this effective tool allows to investigate the importance of different processing parameters in laser manufacturing.","PeriodicalId":14438,"journal":{"name":"International Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2023-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47767852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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