Caroline Ribeiro Pereira, L. A. Abreu, D. Knupp, L. Jardim, Matheus Henrique da Silva Siqueira
This article deals with an analysis of uncertainties applied to a bioheat transfer problem containing a deep brain stimulation lead. The classic two-dimensional bioheat transfer equation in cylindrical coordinates was considered in the mathematical formulation. The electric potential was solved with a Laplace equation to incorporate the DBS lead effects. Thus, the solution for the electric potential was coupled to the temperature problem, considering an external heat transfer rate. The analysis under uncertainties was performed by the Monte Carlo method considering different types of uncertainties for all parameters of the mathematical model. The uncertainties were chosen according to the information available in the literature in order to analyze the problem more realistically. The solutions showed a significant variation in the temperature profile over time when considering the random variations in the parameters.
{"title":"Analysis under Uncertainty with the Monte Carlo Method Applied to a Bioheat Transfer Problem with Coupled Deep Brain Stimulation Lead","authors":"Caroline Ribeiro Pereira, L. A. Abreu, D. Knupp, L. Jardim, Matheus Henrique da Silva Siqueira","doi":"10.4028/p-b6Ix0E","DOIUrl":"https://doi.org/10.4028/p-b6Ix0E","url":null,"abstract":"This article deals with an analysis of uncertainties applied to a bioheat transfer problem containing a deep brain stimulation lead. The classic two-dimensional bioheat transfer equation in cylindrical coordinates was considered in the mathematical formulation. The electric potential was solved with a Laplace equation to incorporate the DBS lead effects. Thus, the solution for the electric potential was coupled to the temperature problem, considering an external heat transfer rate. The analysis under uncertainties was performed by the Monte Carlo method considering different types of uncertainties for all parameters of the mathematical model. The uncertainties were chosen according to the information available in the literature in order to analyze the problem more realistically. The solutions showed a significant variation in the temperature profile over time when considering the random variations in the parameters.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"427 1","pages":"37 - 46"},"PeriodicalIF":0.0,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46577735","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}
D. V. E. Barbosa, Marcio Cardoso Jr., L. F. B. Oliveira, A. Fredere, Cristian Gabriel de Abreu Heylmann, Paulo Carvalho, J. E. Faccion, S. M. Viana, A. J. da Silva Neto, A. Silveira, L. Rocha
This paper presents a landscape evolution model based on physical processes – hillslope processes and fluvial erosion, transport, and deposition – solved by numerical methodology. That is, through the solution of differential equations approximated by numerical methods. In this case, hillslope processes are modeled through the classical diffusion equation, discretized by the finite volume method. Fluvial erosion, transport, and deposition are modeled by the fluvial potential equations (stream power law). For this, the approximation is performed by the finite difference method. The topography – initial condition – is set by digital elevation models, obtained from satellite images. These are Raster datasets, that each cell contains a representative elevation value. The drainage is determined through the classical algorithm D8, which performs a scan on the digital elevation model, tracing routes of greater slopes between the cells. The algorithm execution flowchart is presented, and the model is validated. Finally, a geomorphological study is presented in the Piratini river basin, showing thar developed model mimics largescale natural phenomena of watershed processes.
{"title":"Implementation, Validation and Study Case of a Landscape Evolution Model Algorithm","authors":"D. V. E. Barbosa, Marcio Cardoso Jr., L. F. B. Oliveira, A. Fredere, Cristian Gabriel de Abreu Heylmann, Paulo Carvalho, J. E. Faccion, S. M. Viana, A. J. da Silva Neto, A. Silveira, L. Rocha","doi":"10.4028/p-ooGbR9","DOIUrl":"https://doi.org/10.4028/p-ooGbR9","url":null,"abstract":"This paper presents a landscape evolution model based on physical processes – hillslope processes and fluvial erosion, transport, and deposition – solved by numerical methodology. That is, through the solution of differential equations approximated by numerical methods. In this case, hillslope processes are modeled through the classical diffusion equation, discretized by the finite volume method. Fluvial erosion, transport, and deposition are modeled by the fluvial potential equations (stream power law). For this, the approximation is performed by the finite difference method. The topography – initial condition – is set by digital elevation models, obtained from satellite images. These are Raster datasets, that each cell contains a representative elevation value. The drainage is determined through the classical algorithm D8, which performs a scan on the digital elevation model, tracing routes of greater slopes between the cells. The algorithm execution flowchart is presented, and the model is validated. Finally, a geomorphological study is presented in the Piratini river basin, showing thar developed model mimics largescale natural phenomena of watershed processes.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"427 1","pages":"13 - 23"},"PeriodicalIF":0.0,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46685359","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}
L. Pinheiro, Andreia H. Gomes, C. Fortes, João Santos
SAFEPORT safety system aims to daily reports to the Sines harbor administration, potential emergency situations regarding ships’ operation in port areas caused by extreme weather-oceanographic conditions, that may occur in the next three days. It consists of a set of numerical models and a qualitative risk assessment and forecasting. It uses forecasts provided offshore of the area under the study of sea agitation, wind and tide. The characterization of the response of the free and moored ships at a berth is performed using numerical models which deal with formulations in the frequency and time domain. The system issue alerts, through danger levels associated with risk levels of exceedance of recommended values for movements and forces imposed on ship mooring systems. SAFEPORT can be adapted to any port. So far, it has been developed and adapted to three terminals of the port of Sines, where three different ships were simulated. This paper presents the developments made to date of the safety system, in terms of its implementation and validation. The numerical models run every day, in real-time mode, in a computer cluster. The results are disseminated on a web page and a mobile application in a variety of formats.
{"title":"Implementation and Validation of SAFEPORT System at Sines Harbour","authors":"L. Pinheiro, Andreia H. Gomes, C. Fortes, João Santos","doi":"10.4028/p-2SBfIR","DOIUrl":"https://doi.org/10.4028/p-2SBfIR","url":null,"abstract":"SAFEPORT safety system aims to daily reports to the Sines harbor administration, potential emergency situations regarding ships’ operation in port areas caused by extreme weather-oceanographic conditions, that may occur in the next three days. It consists of a set of numerical models and a qualitative risk assessment and forecasting. It uses forecasts provided offshore of the area under the study of sea agitation, wind and tide. The characterization of the response of the free and moored ships at a berth is performed using numerical models which deal with formulations in the frequency and time domain. The system issue alerts, through danger levels associated with risk levels of exceedance of recommended values for movements and forces imposed on ship mooring systems. SAFEPORT can be adapted to any port. So far, it has been developed and adapted to three terminals of the port of Sines, where three different ships were simulated. This paper presents the developments made to date of the safety system, in terms of its implementation and validation. The numerical models run every day, in real-time mode, in a computer cluster. The results are disseminated on a web page and a mobile application in a variety of formats.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"427 1","pages":"215 - 226"},"PeriodicalIF":0.0,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47213396","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}
Carolina Pinz Medronha, Ana Paula Rozado Gomes, G. J. Weymar, C. C. de Escobar, D. Buske
This work aimed to analyze the atmospheric dispersion of ammonia gas (NH3) caused by a hypothetical leak in a tanker truck due to an accident during its transport. These accidents with dangerous products in road transport are unpredictable and can generate severe impacts on communities' borders and the environment close to the accident site. With the use of mathematical models, it is possible to estimate, assuming that there was an accidental release, how far, from the point of leakage to the cloud formed in the atmosphere will move until it is diluted in a way that does not pose a danger of toxicity. In this work, the ALOHA software and Google Earth will be used to estimate the dispersion of this toxic gas in different scenarios, varying the stability class and the height of the leak orifice. Among the proposed and analyzed scenarios, the results show that the plume with the greatest reach was 948 m in the red zone (AEGL 3 - 1100 ppm or 769 mg/m3), 1900 meters in the orange zone (AEGL 2 - 160 ppm or 112 mg /m3) and 3600 meters in the yellow zone (AEGL 1 - 30 ppm or 21 mg/m3).
{"title":"Mathematical Modeling of Atmospheric Dispersion from Accidental Release of Ammonia (NH3) during Road Transport","authors":"Carolina Pinz Medronha, Ana Paula Rozado Gomes, G. J. Weymar, C. C. de Escobar, D. Buske","doi":"10.4028/p-P4v9qE","DOIUrl":"https://doi.org/10.4028/p-P4v9qE","url":null,"abstract":"This work aimed to analyze the atmospheric dispersion of ammonia gas (NH3) caused by a hypothetical leak in a tanker truck due to an accident during its transport. These accidents with dangerous products in road transport are unpredictable and can generate severe impacts on communities' borders and the environment close to the accident site. With the use of mathematical models, it is possible to estimate, assuming that there was an accidental release, how far, from the point of leakage to the cloud formed in the atmosphere will move until it is diluted in a way that does not pose a danger of toxicity. In this work, the ALOHA software and Google Earth will be used to estimate the dispersion of this toxic gas in different scenarios, varying the stability class and the height of the leak orifice. Among the proposed and analyzed scenarios, the results show that the plume with the greatest reach was 948 m in the red zone (AEGL 3 - 1100 ppm or 769 mg/m3), 1900 meters in the orange zone (AEGL 2 - 160 ppm or 112 mg /m3) and 3600 meters in the yellow zone (AEGL 1 - 30 ppm or 21 mg/m3).","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"427 1","pages":"25 - 33"},"PeriodicalIF":0.0,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46462922","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}
R. Maciel, B. N. Machado, P. Oleinik, E. D. dos Santos, M. N. Gomes, L. Isoldi
This work presents a two-dimensional numerical analysis of a wave channel. The goal is to investigate a methodology that uses transient velocity data as means to impose velocity boundary condition for generating numerical waves. To do so, a numerical wave channel was simulated using irregular waves. These waves were obtained using the WaveMIMO methodology, which converts sea data from a spectral model into time series of free surface elevation, and then converts this elevation into transient discrete wave velocity data. For the numerical analysis, computational fluid dynamics ANSYS Fluent software was employed, which is based on the finite volume method. The computational domain and mesh were generated using GMSH software, and the nonlinear multiphase model volume of fluid (VOF) was applied to tackle water-air interaction. In general, the results obtained through the use of discrete data as velocity boundary condition presented a good agreement with free surface elevation converted from the spectral model, and the tests performed provided further insight into the parameters which affect this methodology. Since many studies use regular waves, the proposed investigation stands out for its capacity to improve the use of realistic sea state data in numerical simulations of wave energy converters.
{"title":"Investigation of Numerical Irregular Wave Generation Using Transient Discrete Data as Boundary Conditions of Prescribed Velocity","authors":"R. Maciel, B. N. Machado, P. Oleinik, E. D. dos Santos, M. N. Gomes, L. Isoldi","doi":"10.4028/p-s0MLH2","DOIUrl":"https://doi.org/10.4028/p-s0MLH2","url":null,"abstract":"This work presents a two-dimensional numerical analysis of a wave channel. The goal is to investigate a methodology that uses transient velocity data as means to impose velocity boundary condition for generating numerical waves. To do so, a numerical wave channel was simulated using irregular waves. These waves were obtained using the WaveMIMO methodology, which converts sea data from a spectral model into time series of free surface elevation, and then converts this elevation into transient discrete wave velocity data. For the numerical analysis, computational fluid dynamics ANSYS Fluent software was employed, which is based on the finite volume method. The computational domain and mesh were generated using GMSH software, and the nonlinear multiphase model volume of fluid (VOF) was applied to tackle water-air interaction. In general, the results obtained through the use of discrete data as velocity boundary condition presented a good agreement with free surface elevation converted from the spectral model, and the tests performed provided further insight into the parameters which affect this methodology. Since many studies use regular waves, the proposed investigation stands out for its capacity to improve the use of realistic sea state data in numerical simulations of wave energy converters.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"427 1","pages":"227 - 235"},"PeriodicalIF":0.0,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42064203","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 work investigates how the configuration of the geometric parameters of a radial crystallizer influences the results of the crystallization of lovastatin by antisolvent and using a multi-scale computational fluid dynamics (CFD) model. The OPENFOAM open-source software uses macro and micromixing expressions for flow, and complete energy and population equilibrium equations during nucleation and crystal growth. The model is based on the Reynolds-Averaged-Navier-Stokes (RANS) equation, along with a multi-environment probability density function (PDF) model and the spatially semi-discretized population equilibrium equation, operating a high-resolution finite volume method. The variation crystallizer construction parameters provided another crystallizer design, and analyses demonstrated improved performance and effects on crystal distribution.
{"title":"Numerical Study of the Influence of the Geometric Parameters of a Radial Crystalizer Using a Multiscale CFD Model","authors":"Gustavo Villela Rodrigues, Cezar A. da Rosa","doi":"10.4028/p-QO9GSb","DOIUrl":"https://doi.org/10.4028/p-QO9GSb","url":null,"abstract":"This work investigates how the configuration of the geometric parameters of a radial crystallizer influences the results of the crystallization of lovastatin by antisolvent and using a multi-scale computational fluid dynamics (CFD) model. The OPENFOAM open-source software uses macro and micromixing expressions for flow, and complete energy and population equilibrium equations during nucleation and crystal growth. The model is based on the Reynolds-Averaged-Navier-Stokes (RANS) equation, along with a multi-environment probability density function (PDF) model and the spatially semi-discretized population equilibrium equation, operating a high-resolution finite volume method. The variation crystallizer construction parameters provided another crystallizer design, and analyses demonstrated improved performance and effects on crystal distribution.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"427 1","pages":"47 - 59"},"PeriodicalIF":0.0,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45277505","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}
Oscillating water column (OWC) wave energy converters can be integrated in harbor protection structures, such as vertical, rubble mound and piled breakwaters. The interaction between the incident wave and the structure, in which the OWC device is integrated, is significantly different, since the structure of the vertical breakwater is impermeable, while that of the rubble mound breakwater is porous. The performance of the OWC device for the three configurations is analyzed for a range of wave periods from 6 to 12 s and a wave height of 1 m. The OWC device integrated into the vertical breakwater shows the best performance (maximum mean pneumatic power of 70 kW), and the mean pneumatic power is globally 3 % higher than that of the OWC device integrated into the rubble mound breakwater (maximum mean pneumatic power of 67.4 kW). The performance of the OWC device integrated into the piled breakwater shows a similar trend to the OWC device integrated into the vertical breakwater for wave periods lower than 9 s, but it has a significant loss of performance for higher wave periods.
{"title":"Performance of an Oscillating Water Column Wave Energy Converter Integrated with Three Types of Harbor Protection Structures","authors":"E. Didier, P. Teixeira","doi":"10.4028/p-BL5v8v","DOIUrl":"https://doi.org/10.4028/p-BL5v8v","url":null,"abstract":"Oscillating water column (OWC) wave energy converters can be integrated in harbor protection structures, such as vertical, rubble mound and piled breakwaters. The interaction between the incident wave and the structure, in which the OWC device is integrated, is significantly different, since the structure of the vertical breakwater is impermeable, while that of the rubble mound breakwater is porous. The performance of the OWC device for the three configurations is analyzed for a range of wave periods from 6 to 12 s and a wave height of 1 m. The OWC device integrated into the vertical breakwater shows the best performance (maximum mean pneumatic power of 70 kW), and the mean pneumatic power is globally 3 % higher than that of the OWC device integrated into the rubble mound breakwater (maximum mean pneumatic power of 67.4 kW). The performance of the OWC device integrated into the piled breakwater shows a similar trend to the OWC device integrated into the vertical breakwater for wave periods lower than 9 s, but it has a significant loss of performance for higher wave periods.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"427 1","pages":"63 - 73"},"PeriodicalIF":0.0,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43303351","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. Domingues, J. Ramalho, Honório Joaquim Fernando
Earth-air heat exchangers (EAHE) consist of buried ducts and a ventilation system, which require minimal electricity, making them a cost-effective and sustainable solution for improving the thermal conditions of built environments. To enhance the efficiency of the EAHE system and optimize its use of the soil's thermal potential, we employed a galvanized block with a cross-sectional area of 1.5 m2 around the duct. The simulations conducted in this study used climatic data from Viamão, a city in southern Brazil, and demonstrated the effectiveness of this strategy. The galvanized block increased the thermal conductivity of the soil region and enabled the EAHE system to utilize higher quantities of thermal energy. The first part of the work highlights the importance of block coupling in improving thermal efficiency and the two potentials of EAHE systems. We also introduce a new method for calculating EAHE efficiency throughout the year. We name it maximum efficiency because it measures how much thermal potential an EAHE installation can extract from the highest amount available in the soil during the year. Subsequently, we conducted simulations of ducts at different depths to evaluate their performance. Our results showed that annual efficiencies increased significantly with the addition of the galvanized block. We also found how the installation depth impacts the thermal potentials. Specifically, we obtained almost 4.0°C and 3.8°C for the (annual RMS) soil and EAHE thermal potentials, respectively, at 3.5m.
{"title":"Maximizing Efficiency of Earth-Air Heat Exchangers with Galvanized Blocks","authors":"A. Domingues, J. Ramalho, Honório Joaquim Fernando","doi":"10.4028/p-QS2lqy","DOIUrl":"https://doi.org/10.4028/p-QS2lqy","url":null,"abstract":"Earth-air heat exchangers (EAHE) consist of buried ducts and a ventilation system, which require minimal electricity, making them a cost-effective and sustainable solution for improving the thermal conditions of built environments. To enhance the efficiency of the EAHE system and optimize its use of the soil's thermal potential, we employed a galvanized block with a cross-sectional area of 1.5 m2 around the duct. The simulations conducted in this study used climatic data from Viamão, a city in southern Brazil, and demonstrated the effectiveness of this strategy. The galvanized block increased the thermal conductivity of the soil region and enabled the EAHE system to utilize higher quantities of thermal energy. The first part of the work highlights the importance of block coupling in improving thermal efficiency and the two potentials of EAHE systems. We also introduce a new method for calculating EAHE efficiency throughout the year. We name it maximum efficiency because it measures how much thermal potential an EAHE installation can extract from the highest amount available in the soil during the year. Subsequently, we conducted simulations of ducts at different depths to evaluate their performance. Our results showed that annual efficiencies increased significantly with the addition of the galvanized block. We also found how the installation depth impacts the thermal potentials. Specifically, we obtained almost 4.0°C and 3.8°C for the (annual RMS) soil and EAHE thermal potentials, respectively, at 3.5m.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"427 1","pages":"75 - 84"},"PeriodicalIF":0.0,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49008301","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}
G. M. C. Magalhães, Marcello Chiomento, L. Isoldi, J. A. Souza, E. D. dos Santos
The present numerical study proposes the application of the constructal theory for the build of empty channels inserted in a porous domain, representing the liquid resin infusion process. Two different strategies are employed: 1) I-shaped pre-defined configuration for the empty channel, 2) constructive technique (evolutionary) where the empty channel is built from an elemental configuration and using the performance indicator to define the new position of each empty channel element. It is investigated the influence of geometry over the impregnation time and the amount of wasted mass of resin during the process. The same fluid dynamic conditions and the maximum occupation area of the empty channel were defined for the different strategies. The finite volume method (FVM) and volume of fluid (VOF) were used for the solution of mass, momentum, and transport of resin equations, which model the flow of resin/air mixture. Darcy’s law is applied to represent the porous medium resistance. Results showed that the constructive technique was highly promising in the proposition of configurations that reduced the time of impregnation of resin in the porous medium. Moreover, it was observed that, for the present fluid dynamic conditions, giving more freedom for the formation of empty channels shape also led to a reduction of filling time of resin impregnation in the porous mold.
{"title":"Constructal Theory Applied to the Growth of Injection Channels in a Liquid Resin Infusion Problem","authors":"G. M. C. Magalhães, Marcello Chiomento, L. Isoldi, J. A. Souza, E. D. dos Santos","doi":"10.4028/p-26iX9b","DOIUrl":"https://doi.org/10.4028/p-26iX9b","url":null,"abstract":"The present numerical study proposes the application of the constructal theory for the build of empty channels inserted in a porous domain, representing the liquid resin infusion process. Two different strategies are employed: 1) I-shaped pre-defined configuration for the empty channel, 2) constructive technique (evolutionary) where the empty channel is built from an elemental configuration and using the performance indicator to define the new position of each empty channel element. It is investigated the influence of geometry over the impregnation time and the amount of wasted mass of resin during the process. The same fluid dynamic conditions and the maximum occupation area of the empty channel were defined for the different strategies. The finite volume method (FVM) and volume of fluid (VOF) were used for the solution of mass, momentum, and transport of resin equations, which model the flow of resin/air mixture. Darcy’s law is applied to represent the porous medium resistance. Results showed that the constructive technique was highly promising in the proposition of configurations that reduced the time of impregnation of resin in the porous medium. Moreover, it was observed that, for the present fluid dynamic conditions, giving more freedom for the formation of empty channels shape also led to a reduction of filling time of resin impregnation in the porous mold.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"427 1","pages":"193 - 203"},"PeriodicalIF":0.0,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45046048","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}
Giovanni Antonio Vielma Vivas, M. K. Rodrigues, L. Rocha, E. D. dos Santos, R. Brum, L. Isoldi
The earth-air heat exchanger (EAHE) is a sustainable option that allows the electrical energy consumption reduction in buildings. The objective of this study is to evaluate the influence of the incorporation of the thermal energy storage principle based on phase change materials (PCM) into the EAHE on its thermal potential. For this, a three-dimensional numerical model of the PCM coupled to the EAHE (EAHE-PCM) was developed based on the effective heat capacity method and adapted to the climatic conditions and soil characteristics of the Viamão city, Rio Grande do Sul State, Brazil. It was found that for a duct diameter and length of 0.11 m and 25.77 m, the incorporation of PCM to EAHE improved by 8.90% and 3.97% in the average annual thermal potential of heating and cooling, respectively. In addition, the average monthly thermal potential increased 19.70% (heating) and 8.48%(cooling), for the months of May and December, respectively, when the PCM was integrated into the system.
{"title":"Computational Modeling of an Earth-Air Heat Exchanger Integrated with Phase Change Materials: A Case Study Performed for the Viamão City, Rio Grande do Sul State, Brazil","authors":"Giovanni Antonio Vielma Vivas, M. K. Rodrigues, L. Rocha, E. D. dos Santos, R. Brum, L. Isoldi","doi":"10.4028/p-n7qBvb","DOIUrl":"https://doi.org/10.4028/p-n7qBvb","url":null,"abstract":"The earth-air heat exchanger (EAHE) is a sustainable option that allows the electrical energy consumption reduction in buildings. The objective of this study is to evaluate the influence of the incorporation of the thermal energy storage principle based on phase change materials (PCM) into the EAHE on its thermal potential. For this, a three-dimensional numerical model of the PCM coupled to the EAHE (EAHE-PCM) was developed based on the effective heat capacity method and adapted to the climatic conditions and soil characteristics of the Viamão city, Rio Grande do Sul State, Brazil. It was found that for a duct diameter and length of 0.11 m and 25.77 m, the incorporation of PCM to EAHE improved by 8.90% and 3.97% in the average annual thermal potential of heating and cooling, respectively. In addition, the average monthly thermal potential increased 19.70% (heating) and 8.48%(cooling), for the months of May and December, respectively, when the PCM was integrated into the system.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"427 1","pages":"85 - 94"},"PeriodicalIF":0.0,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45731449","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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