Pub Date : 2023-02-08DOI: 10.5380/reterm.v21i3.89669
D. A. S. Rossato, H. B. Cornel, L. G. A. Brites, A. Diógenes
Aiming at reducing the emission of pollutants from automotive vehicles, international commissions indicate, at each given period, a target of admissible values for these pollutants, to be implemented by the automakers. A case like the future implementation of EuroVII, from 2025, in European regions. In parallel to these conditions, there are many studies with the objective of seeking alternatives for the propulsion of these combustion vehicles, for example, the application of fully electric or hybrid vehicles. This article aims to develop and implement a mathematical model for a proposal for a hybrid engine, in a low-power truck, resulting in a small diesel engine, powering the vehicle's alternator and battery, generating the charging for use in a main electric motor, that is, to develop with a focus on energy conservation and the environment, with a reduction in the size of a combustion engine and its emissions.
{"title":"A PROPOSAL FOR A HYBRID POWER TRAIN FOR A TRUCK","authors":"D. A. S. Rossato, H. B. Cornel, L. G. A. Brites, A. Diógenes","doi":"10.5380/reterm.v21i3.89669","DOIUrl":"https://doi.org/10.5380/reterm.v21i3.89669","url":null,"abstract":"Aiming at reducing the emission of pollutants from automotive vehicles, international commissions indicate, at each given period, a target of admissible values for these pollutants, to be implemented by the automakers. A case like the future implementation of EuroVII, from 2025, in European regions. In parallel to these conditions, there are many studies with the objective of seeking alternatives for the propulsion of these combustion vehicles, for example, the application of fully electric or hybrid vehicles. This article aims to develop and implement a mathematical model for a proposal for a hybrid engine, in a low-power truck, resulting in a small diesel engine, powering the vehicle's alternator and battery, generating the charging for use in a main electric motor, that is, to develop with a focus on energy conservation and the environment, with a reduction in the size of a combustion engine and its emissions.","PeriodicalId":106768,"journal":{"name":"Revista de Engenharia Térmica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125312439","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}
Pub Date : 2023-02-08DOI: 10.5380/reterm.v21i3.89668
Gustavo Trindade, Luís Antônio Bortolaia
The increase in global and Brazilian energy demand plus environmental concern due to pollutant emissions are motivating investigation and development of sustainable energy sources and the interaction between them. In this context, electricity generation through solar and solid urban waste energy harnessing has become an effective option for Brazilian energy matrix diversification. Therefore, in order to ratify this trend, a thermodynamic analysis of a 200 kWe micro gas turbine using biogas as fuel and photovoltaic panels to drive compressor shaft is presented in this paper. In terms of methodology, Engineering Equation Solver (EES) Demo was used to run a classic steady state thermodynamic model and a parametric analysis to evaluate MGT performance with a PV system integrated in order to assess specific fuel consumption reduction (SFC) at Belo Horizonte, Minas Gerais, Brazil, operation. Radiasol 2 was the software used to acquire solar insolation data over the year. The fuel economy occurs since power produced in turbine does not need to be discounted to drive compressor shaft during periods when solar insolation is present or when energy generation during the day is sufficient to be credited as Brazilian legislation allows grid integrated systems. In cases that solar energy is not enough or absent, a transmission mechanism similar to a clutch should be considered as well as proposed in other studies to guarantee uninterrupted system operation. Futhermore, an economic analysis was performed to evaluate kWh cost for conventional and hybrid systems. Interest rate, inflation, construction period and amortization period are important parameters taken into account to calculated annuity factor that must be evaluated to predict energy cost. The thermodynamic results showed that SFC=0,718 kg/kWh for conventional operation and SFC=0,266 kg/kWh for hybrid operation for the best operating compressor pressures ratio. The economic results showed that payback time for MGT and MGT with compressor photovoltaic drive are lower than lifetime systems, and hybrid MGT electricity cost is lower when compared to paid ones nowadays.
{"title":"THERMODYNAMIC AND ECONOMIC ANALYSIS OF A BIOGAS -FUELED MICRO GAS TURBINE WITH COMPRESSOR PHOTOVOLTAIC DRIVE","authors":"Gustavo Trindade, Luís Antônio Bortolaia","doi":"10.5380/reterm.v21i3.89668","DOIUrl":"https://doi.org/10.5380/reterm.v21i3.89668","url":null,"abstract":"The increase in global and Brazilian energy demand plus environmental concern due to pollutant emissions are motivating investigation and development of sustainable energy sources and the interaction between them. In this context, electricity generation through solar and solid urban waste energy harnessing has become an effective option for Brazilian energy matrix diversification. Therefore, in order to ratify this trend, a thermodynamic analysis of a 200 kWe micro gas turbine using biogas as fuel and photovoltaic panels to drive compressor shaft is presented in this paper. In terms of methodology, Engineering Equation Solver (EES) Demo was used to run a classic steady state thermodynamic model and a parametric analysis to evaluate MGT performance with a PV system integrated in order to assess specific fuel consumption reduction (SFC) at Belo Horizonte, Minas Gerais, Brazil, operation. Radiasol 2 was the software used to acquire solar insolation data over the year. The fuel economy occurs since power produced in turbine does not need to be discounted to drive compressor shaft during periods when solar insolation is present or when energy generation during the day is sufficient to be credited as Brazilian legislation allows grid integrated systems. In cases that solar energy is not enough or absent, a transmission mechanism similar to a clutch should be considered as well as proposed in other studies to guarantee uninterrupted system operation. Futhermore, an economic analysis was performed to evaluate kWh cost for conventional and hybrid systems. Interest rate, inflation, construction period and amortization period are important parameters taken into account to calculated annuity factor that must be evaluated to predict energy cost. The thermodynamic results showed that SFC=0,718 kg/kWh for conventional operation and SFC=0,266 kg/kWh for hybrid operation for the best operating compressor pressures ratio. The economic results showed that payback time for MGT and MGT with compressor photovoltaic drive are lower than lifetime systems, and hybrid MGT electricity cost is lower when compared to paid ones nowadays.","PeriodicalId":106768,"journal":{"name":"Revista de Engenharia Térmica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114925420","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}
Pub Date : 2023-02-08DOI: 10.5380/reterm.v21i3.89704
M. C. Souza, W. D. Badaró, V. Monine, C. C. Ferreira, N. O. Tapanes
Duplex stainless steels are widely used in the chemical, nuclear and oil and gas industries. They have an austenitic-ferritic microstructure, in equal parts. In this work, the impacts on the mechanical properties, on the metallographic behavior and the analysis of the residual stresses caused after the welding process by coated electrode were analyzed. In these analyses, a specimen produced from a 10 mm thick duplex sheet was welded, and tensile tests, micrography and residual stress analysis by x-ray diffraction were carried out. The tensile test results showed values higher than those required by the material's manufacturing standard. The specimens broke in the base metal during the tests, indicating that the welding parameters were properly specified and applied to the specimen. The metallographic analysis showed an increase in the ferritic phase in the weld region, which makes this region susceptible to pitting corrosion in environments containing chlorides. Residual stress analysis showed tensile stresses in the weld bead, in the longitudinal and transverse directions, and in the HAZ and in the root compressive stresses in the transverse direction and tensile stresses in the longitudinal direction. These stresses must be considered in the design of equipment and structures manufactured from this steel and when using coated electrode welding, to avoid premature failure, especially fatigue failure.
{"title":"STUDY OF MECHANICAL PROPERTIES, MICROSTRUCTURE AND RESIDUAL STRESS BY X-RAY DIFFRACTION IN WELDED JOINTS OF DUPLEX STEEL UNS S 31803 BY COATED ELECTRODE","authors":"M. C. Souza, W. D. Badaró, V. Monine, C. C. Ferreira, N. O. Tapanes","doi":"10.5380/reterm.v21i3.89704","DOIUrl":"https://doi.org/10.5380/reterm.v21i3.89704","url":null,"abstract":"Duplex stainless steels are widely used in the chemical, nuclear and oil and gas industries. They have an austenitic-ferritic microstructure, in equal parts. In this work, the impacts on the mechanical properties, on the metallographic behavior and the analysis of the residual stresses caused after the welding process by coated electrode were analyzed. In these analyses, a specimen produced from a 10 mm thick duplex sheet was welded, and tensile tests, micrography and residual stress analysis by x-ray diffraction were carried out. The tensile test results showed values higher than those required by the material's manufacturing standard. The specimens broke in the base metal during the tests, indicating that the welding parameters were properly specified and applied to the specimen. The metallographic analysis showed an increase in the ferritic phase in the weld region, which makes this region susceptible to pitting corrosion in environments containing chlorides. Residual stress analysis showed tensile stresses in the weld bead, in the longitudinal and transverse directions, and in the HAZ and in the root compressive stresses in the transverse direction and tensile stresses in the longitudinal direction. These stresses must be considered in the design of equipment and structures manufactured from this steel and when using coated electrode welding, to avoid premature failure, especially fatigue failure.","PeriodicalId":106768,"journal":{"name":"Revista de Engenharia Térmica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124225321","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}
Pub Date : 2023-02-06DOI: 10.5380/reterm.v21i4.89673
G. R. Silva, T. Galo, A. M. Soares Jr., L. G. Oliveira
Since van der Waals' first publication, a lot of equations of state have been proposed to represent the PVT behavior of pure compounds, as is the case with GEOS3C, which is a new form of generalized cubic equation of state that uses a temperature function dependent on three adjustable empirical parameters. In order to obtain the parameters that lead to the lowest errors of vapor pressure and saturated liquid volume predictions, it is possible to turn this problem into a multiobjective optimization problem. In this context, a modified MOPSO algorithm was employed. This method has the main advantage to provide a set of solutions that show the existing conflict in the attempt to minimize the properties of interest. Substances from different chemical families were used to evaluate the methodology proposed in this work and comparisons against experimental data were made. Results showed that the values obtained through multiobjective optimization for GEOS3C adjustable parameters provide better or equivalent predictions for all calculated thermodynamic properties. In addition, it was possible to observe a correlation between the parameters in the viable regions of the Pareto fronts: C1 assuming a constant value, whereas C2 and C3 are linearly dependent on each other
自van der Waals首次发表以来，已经提出了许多状态方程来表示纯化合物的PVT行为，例如GEOS3C，它是一种新形式的广义三次状态方程，使用依赖于三个可调经验参数的温度函数。为了得到导致蒸汽压和饱和液体体积预测误差最小的参数，可以将该问题转化为多目标优化问题。为此，采用了一种改进的MOPSO算法。这种方法的主要优点是提供了一组显示现有冲突的解决方案，以尽量减少感兴趣的属性。使用不同化学家族的物质来评估本工作中提出的方法，并与实验数据进行了比较。结果表明，通过对GEOS3C可调参数进行多目标优化得到的数值能够更好或等效地预测所有计算的热力学性质。此外，可以观察到帕累托锋面可行区域的参数之间的相关性:C1假设恒定值，而C2和C3是线性依赖于彼此的
{"title":"THERMODYNAMIC PROPERTIES CALCULATION USING A MULTIOBJECTIVE APPROACH IN ESTIMATING THE PARAMETERS OF THE GEOS3C EQUATION OF STATE","authors":"G. R. Silva, T. Galo, A. M. Soares Jr., L. G. Oliveira","doi":"10.5380/reterm.v21i4.89673","DOIUrl":"https://doi.org/10.5380/reterm.v21i4.89673","url":null,"abstract":"Since van der Waals' first publication, a lot of equations of state have been proposed to represent the PVT behavior of pure compounds, as is the case with GEOS3C, which is a new form of generalized cubic equation of state that uses a temperature function dependent on three adjustable empirical parameters. In order to obtain the parameters that lead to the lowest errors of vapor pressure and saturated liquid volume predictions, it is possible to turn this problem into a multiobjective optimization problem. In this context, a modified MOPSO algorithm was employed. This method has the main advantage to provide a set of solutions that show the existing conflict in the attempt to minimize the properties of interest. Substances from different chemical families were used to evaluate the methodology proposed in this work and comparisons against experimental data were made. Results showed that the values obtained through multiobjective optimization for GEOS3C adjustable parameters provide better or equivalent predictions for all calculated thermodynamic properties. In addition, it was possible to observe a correlation between the parameters in the viable regions of the Pareto fronts: C1 assuming a constant value, whereas C2 and C3 are linearly dependent on each other","PeriodicalId":106768,"journal":{"name":"Revista de Engenharia Térmica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133226454","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}
Pub Date : 2023-02-06DOI: 10.5380/reterm.v21i4.89677
G. P. Bianch, A. L. Braun
Air quality, thermal comfort and internal circulation in urban areas are closely linked to the promotion of natural ventilation in buildings. In this sense, the main objectives of the present work are to study the effect of internal circulation in buildings with different openings and the phenomenon of pollutant dispersion in naturally ventilated buildings under non-isothermal conditions using a numerical model for incompressible flows with heat and mass transport. For the flow simulation, a semi-implicit Characteristic-Based Split (CBS) scheme is used in the context of the Finite Element Method (FEM), where linear tetrahedral elements are used for spatial discretization. Turbulence is treated using the Large Eddy Simulation (LES) methodology and thermal effects are considered in the momentum balance equation through buoyancy forces, which are calculated taking into account the Boussinesq approximation. Classical examples are analyzed to verify the numerical model proposed here, as well as the forms of natural ventilation and, finally, a numerical investigation is carried out considering the dispersion of pollutants and the thermal effects simultaneously. In addition to ensuring air exchange while maintaining a healthy environment, ventilation helps to disperse pollutants and promotes thermal comfort, both inside the building and in the street canyon, as indicated by results obtained.
{"title":"NUMERICAL ANALYSIS OF CIRCULATION AND DISPERSION OF POLLUTANTS IN VENTILATED BUILDINGS UNDER NON-ISOTHERMAL CONDITIONS","authors":"G. P. Bianch, A. L. Braun","doi":"10.5380/reterm.v21i4.89677","DOIUrl":"https://doi.org/10.5380/reterm.v21i4.89677","url":null,"abstract":"Air quality, thermal comfort and internal circulation in urban areas are closely linked to the promotion of natural ventilation in buildings. In this sense, the main objectives of the present work are to study the effect of internal circulation in buildings with different openings and the phenomenon of pollutant dispersion in naturally ventilated buildings under non-isothermal conditions using a numerical model for incompressible flows with heat and mass transport. For the flow simulation, a semi-implicit Characteristic-Based Split (CBS) scheme is used in the context of the Finite Element Method (FEM), where linear tetrahedral elements are used for spatial discretization. Turbulence is treated using the Large Eddy Simulation (LES) methodology and thermal effects are considered in the momentum balance equation through buoyancy forces, which are calculated taking into account the Boussinesq approximation. Classical examples are analyzed to verify the numerical model proposed here, as well as the forms of natural ventilation and, finally, a numerical investigation is carried out considering the dispersion of pollutants and the thermal effects simultaneously. In addition to ensuring air exchange while maintaining a healthy environment, ventilation helps to disperse pollutants and promotes thermal comfort, both inside the building and in the street canyon, as indicated by results obtained.","PeriodicalId":106768,"journal":{"name":"Revista de Engenharia Térmica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126112625","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}
Pub Date : 2022-10-09DOI: 10.5380/reterm.v21i2.87921
F. Rovai, C. E. Mady
The internal combustion engine performance enhancement is a widely explored subject. Additionally, to pollutant emissions attention, reducing fuel consumption and consequently the greenhouse gas emissions is one of the leading research and development drivers for the future of the engines industry. As the technologies to increase global engine efficiency are becoming less promising (already reaching improvement limits), the next round would be developing technologies capable of recovering the energy rejected to the environment, especially by cooling and exhaust systems. The internal combustion engine efficiency is mainly assessed by its global efficiency, which consists of an energy balance. The exergy analysis enhances the classic energy analysis from the concept of maximum possible work, including the rejected energy, consisting of a handy tool for the feasibility study of energy recovery systems. This article presents and contrasts the energy and the exergy analyses of a flex-fuel internal combustion engine running on its top global efficiency condition. The boundary fuels are hydrous ethanol (E100) and gasoline blend (E22), available fuels in Brazil. The hydrous ethanol fuel properties (octane number, air-fuel ratio, and vaporization enthalpy) theoretically result in higher energetic engine efficiency than E22 in the same engine hardware, with a fixed compression ratio. Preliminary results of this study point 4,5% higher global engine efficiency running on E100 compared to E22. The higher engine energy efficiency running on E100 than E22 does not happen in the Second Law analysis. The classic exergetic efficiency, based on engine brake power, is similar for E22 and E100. The maximum exergetic efficiency, based on destroyed exergy, is 4,1% higher for E22 compared to E100. The estimation and comparison of the exergy rejected to the cooling and the exhaust systems according to the boundary fuel (about 21 kW on average in this case), is fundamental to assess the potential and the availability of any recovery system eventually implemented in the internal combustion engine.
{"title":"EXERGETIC ANALYSIS OF AN INTERNAL COMBUSTION ENGINE RUNNING ON E22 AND E100","authors":"F. Rovai, C. E. Mady","doi":"10.5380/reterm.v21i2.87921","DOIUrl":"https://doi.org/10.5380/reterm.v21i2.87921","url":null,"abstract":"The internal combustion engine performance enhancement is a widely explored subject. Additionally, to pollutant emissions attention, reducing fuel consumption and consequently the greenhouse gas emissions is one of the leading research and development drivers for the future of the engines industry. As the technologies to increase global engine efficiency are becoming less promising (already reaching improvement limits), the next round would be developing technologies capable of recovering the energy rejected to the environment, especially by cooling and exhaust systems. The internal combustion engine efficiency is mainly assessed by its global efficiency, which consists of an energy balance. The exergy analysis enhances the classic energy analysis from the concept of maximum possible work, including the rejected energy, consisting of a handy tool for the feasibility study of energy recovery systems. This article presents and contrasts the energy and the exergy analyses of a flex-fuel internal combustion engine running on its top global efficiency condition. The boundary fuels are hydrous ethanol (E100) and gasoline blend (E22), available fuels in Brazil. The hydrous ethanol fuel properties (octane number, air-fuel ratio, and vaporization enthalpy) theoretically result in higher energetic engine efficiency than E22 in the same engine hardware, with a fixed compression ratio. Preliminary results of this study point 4,5% higher global engine efficiency running on E100 compared to E22. The higher engine energy efficiency running on E100 than E22 does not happen in the Second Law analysis. The classic exergetic efficiency, based on engine brake power, is similar for E22 and E100. The maximum exergetic efficiency, based on destroyed exergy, is 4,1% higher for E22 compared to E100. The estimation and comparison of the exergy rejected to the cooling and the exhaust systems according to the boundary fuel (about 21 kW on average in this case), is fundamental to assess the potential and the availability of any recovery system eventually implemented in the internal combustion engine.","PeriodicalId":106768,"journal":{"name":"Revista de Engenharia Térmica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133345739","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}
Pub Date : 2022-10-09DOI: 10.5380/reterm.v21i2.87918
A. Belizário, J. Simões-Moreira
The air conditioning system of a Data Center is a great challenge for mechanical engineers. At the same time, it is fundamental for computer safety, it is a great energy consumer. Considering that, the present work carried out an analysis in which a solar-powered absorption refrigeration cycle system is combined with a conventional electrical chiller system. The proposed system also introduces the use of PV panels to generate electricity to power the electric chiller. A decision algorithm was developed based on local solar parametric data and cooling demand. A case study was analyzed for a typical data center located in the city of São Paulo, Brazil. Electrical specific installed power demands of 0.5, 1.0, 2.0, 4.0, and 8.0 kW/m² at half and total load were studied. Local solar irradiation and temperature indexes were based on the data obtained from ASHRAE [1]. The results show that, for a typical year, the absorption solar system performs better than the photovoltaic system in most cases (0.5, 1.0, 4.0, and 8.0 kW/m²), except when the baseline of the installation operates near the optimum point of the consumption curve of the chiller, which occurs at 2 kW/m². Finally, the study shows that air conditioning systems powered by solar energy are a great alternative to reduce the energy consumption and operational costs of a Data Center.
{"title":"COMPARISON BETWEEN SOLAR THERMAL-POWERED ABSORPTION REFRIGERATION CYCLE AND PHOTOVOLTAIC-POWERED COOLING TECHNOLOGIES APPLIED TO DATA CENTERs","authors":"A. Belizário, J. Simões-Moreira","doi":"10.5380/reterm.v21i2.87918","DOIUrl":"https://doi.org/10.5380/reterm.v21i2.87918","url":null,"abstract":"The air conditioning system of a Data Center is a great challenge for mechanical engineers. At the same time, it is fundamental for computer safety, it is a great energy consumer. Considering that, the present work carried out an analysis in which a solar-powered absorption refrigeration cycle system is combined with a conventional electrical chiller system. The proposed system also introduces the use of PV panels to generate electricity to power the electric chiller. A decision algorithm was developed based on local solar parametric data and cooling demand. A case study was analyzed for a typical data center located in the city of São Paulo, Brazil. Electrical specific installed power demands of 0.5, 1.0, 2.0, 4.0, and 8.0 kW/m² at half and total load were studied. Local solar irradiation and temperature indexes were based on the data obtained from ASHRAE [1]. The results show that, for a typical year, the absorption solar system performs better than the photovoltaic system in most cases (0.5, 1.0, 4.0, and 8.0 kW/m²), except when the baseline of the installation operates near the optimum point of the consumption curve of the chiller, which occurs at 2 kW/m². Finally, the study shows that air conditioning systems powered by solar energy are a great alternative to reduce the energy consumption and operational costs of a Data Center.","PeriodicalId":106768,"journal":{"name":"Revista de Engenharia Térmica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117193680","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}
Pub Date : 2022-10-09DOI: 10.5380/reterm.v21i2.87916
S. A. Verdério Júnior, V. L. Scalon, S. Oliveira, P. J. Martins Coelho
The transfer of heat and mass by natural convection is present in the most diverse physical and chemical phenomena of nature and engineering equipment. In the last decades, the number of research on natural convection has grown dramatically, highlighting studies in physical-mathematical modeling and numerical solutions, experimental analysis and design and optimization techniques for fluid-thermal systems. This case study analyzed the influence of several numerical parameters in physical-mathematical modeling and numerical solution of natural convection heat transfer problems on isothermal plates with square waves in turbulent conditions of high Rayleigh number. The numerical parameters analyzed were the mesh refinement degree, wall boundary conditions (with or without wall functions implemented in the turbulent parameters) and computational physical domain influence. Free and open-source computational numerical tools were exclusively used in the construction of this work. Meshes with wall functions implemented in turbulent parameters presented greater accuracy and required less computational effort and simulation time, besides enabling the use of a lower degree of mesh refinement. The best numerical configuration of the physical model for the situation problem studied were defined from the criteria of accuracy, computational effort demanded, and stability and numerical convergence of the solution.
{"title":"NATURAL CONVECTION ON CORRUGATED PLATES: A NUMERICAL CASE STUDY ABOUT MESHES, BOUNDARY CONDITIONS AND PHYSICAL DOMAIN DETERMINATION","authors":"S. A. Verdério Júnior, V. L. Scalon, S. Oliveira, P. J. Martins Coelho","doi":"10.5380/reterm.v21i2.87916","DOIUrl":"https://doi.org/10.5380/reterm.v21i2.87916","url":null,"abstract":"The transfer of heat and mass by natural convection is present in the most diverse physical and chemical phenomena of nature and engineering equipment. In the last decades, the number of research on natural convection has grown dramatically, highlighting studies in physical-mathematical modeling and numerical solutions, experimental analysis and design and optimization techniques for fluid-thermal systems. This case study analyzed the influence of several numerical parameters in physical-mathematical modeling and numerical solution of natural convection heat transfer problems on isothermal plates with square waves in turbulent conditions of high Rayleigh number. The numerical parameters analyzed were the mesh refinement degree, wall boundary conditions (with or without wall functions implemented in the turbulent parameters) and computational physical domain influence. Free and open-source computational numerical tools were exclusively used in the construction of this work. Meshes with wall functions implemented in turbulent parameters presented greater accuracy and required less computational effort and simulation time, besides enabling the use of a lower degree of mesh refinement. The best numerical configuration of the physical model for the situation problem studied were defined from the criteria of accuracy, computational effort demanded, and stability and numerical convergence of the solution.","PeriodicalId":106768,"journal":{"name":"Revista de Engenharia Térmica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130211585","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}
Pub Date : 2022-10-09DOI: 10.5380/reterm.v21i2.87917
R. L. Casemiro, N. O. Tapanes, M. C. Souza, A. Santana, W. C. L. Pinto
Worldwide, steel production insistently seeks energy strength, pointing out the precision of application of all energy from the raw material with the objective of increasing production with quality and economically viable. In this sense, the energy assessment is the basis adopted to decide on the manufacture of coke in the industry. With this argument, this paper presents an energy analysis of Heat Recovery furnaces through calorific value, a method specified by the Energy Research Company of Brazil and the Brazilian Association of Metals and Materials for application in calculations in a productive environment. The data of the basic raw materials for the production of coke, the technological analysis and the energy estimation in the manufacture of coke in Coke Ovens Heat Recovery can be found in the proposed method. The present work presents result that demonstrate that the active and efficient use of the calorific value of metallurgical coal produces an energy quality coke for the manufacture of pig iron in the blast furnace.
{"title":"ENERGETIC ESTIMATION OF HEAT-RECOVERY COKE OVEN","authors":"R. L. Casemiro, N. O. Tapanes, M. C. Souza, A. Santana, W. C. L. Pinto","doi":"10.5380/reterm.v21i2.87917","DOIUrl":"https://doi.org/10.5380/reterm.v21i2.87917","url":null,"abstract":"Worldwide, steel production insistently seeks energy strength, pointing out the precision of application of all energy from the raw material with the objective of increasing production with quality and economically viable. In this sense, the energy assessment is the basis adopted to decide on the manufacture of coke in the industry. With this argument, this paper presents an energy analysis of Heat Recovery furnaces through calorific value, a method specified by the Energy Research Company of Brazil and the Brazilian Association of Metals and Materials for application in calculations in a productive environment. The data of the basic raw materials for the production of coke, the technological analysis and the energy estimation in the manufacture of coke in Coke Ovens Heat Recovery can be found in the proposed method. The present work presents result that demonstrate that the active and efficient use of the calorific value of metallurgical coal produces an energy quality coke for the manufacture of pig iron in the blast furnace. ","PeriodicalId":106768,"journal":{"name":"Revista de Engenharia Térmica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132586956","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}
Pub Date : 2022-10-09DOI: 10.5380/reterm.v21i2.87922
I. Matos, R. M. Silva, L. Pimont, P. Lacava
Low thrust values obtained with a hybrid rocket motor (HRM) are a consequence of the difficulty in quickly mixing the fuel and oxidizer, which is characterized by a low regression rate of the fuel grain. Therefore, the measurement of this parameter is of great importance in studies that aim at solutions for this deficiency in HRM. Several studies calculate a reliable value of the average regression rate over time by measuring the total mass of fuel before and after each burn. A method to measure instantaneous regression rate is by acquiring the Helmholtz resonance frequency in the combustion chamber. This work uses a piezoelectric pressure transducer to obtain the Helmholtz frequency mode of the combustion chamber in a laboratory scale test bench with high-density polyethylene (HDPE) and gaseous oxygen, and is based on the principle that this frequency is inversely proportional to the square-root of the chamber volume. With the chamber volume variation, the port diameter of the grain variation is obtained. In conclusion, the calculated variation of port diameter agreed well with the correlation for average regression rate, determined from mass loss during operation.
{"title":"MEASUREMENT OF THE REGRESSION RATE IN A HYBRID ROCKET MOTOR BY ACQUIRING THE HELMHOLTZ FREQUENCY IN THE COMBUSTION CHAMBER","authors":"I. Matos, R. M. Silva, L. Pimont, P. Lacava","doi":"10.5380/reterm.v21i2.87922","DOIUrl":"https://doi.org/10.5380/reterm.v21i2.87922","url":null,"abstract":"Low thrust values obtained with a hybrid rocket motor (HRM) are a consequence of the difficulty in quickly mixing the fuel and oxidizer, which is characterized by a low regression rate of the fuel grain. Therefore, the measurement of this parameter is of great importance in studies that aim at solutions for this deficiency in HRM. Several studies calculate a reliable value of the average regression rate over time by measuring the total mass of fuel before and after each burn. A method to measure instantaneous regression rate is by acquiring the Helmholtz resonance frequency in the combustion chamber. This work uses a piezoelectric pressure transducer to obtain the Helmholtz frequency mode of the combustion chamber in a laboratory scale test bench with high-density polyethylene (HDPE) and gaseous oxygen, and is based on the principle that this frequency is inversely proportional to the square-root of the chamber volume. With the chamber volume variation, the port diameter of the grain variation is obtained. In conclusion, the calculated variation of port diameter agreed well with the correlation for average regression rate, determined from mass loss during operation.","PeriodicalId":106768,"journal":{"name":"Revista de Engenharia Térmica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124463553","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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