Secagem de sólidos porosos granulares
Autor(a) principal: | |
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Data de Publicação: | 2014 |
Tipo de documento: | Tese |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFSCAR |
Texto Completo: | https://repositorio.ufscar.br/handle/ufscar/3949 |
Resumo: | In the present work, an experimental study about heat and mass transfer phenomena was carried out during drying of porous media when subjected to an upward flow of heated air. The cylindrical porous media consisted of non-consolidated particles of activated alumina of several diameters. The particulate system was initially characterized based on the achievement of its main physical, thermal and structural properties. The drying experiments consisted of obtaining sorption isotherms at different operational conditions and in determining moisture and temperature data versus time. The temperature profiles were obtained by thermocouples inserted in the porous body and the moisture content data by the gravimetrical method. The concept of time in series analysis was applied to determine the stationarity of the experimental data. The drying of the porous media was studied theoretically based on the context of the pseudo-homogeneous formulation, which led to the estimation of transport parameters of interest considering two situations: the presence of the external resistance to mass transfer and the interfacial equilibrium condition. The estimated transport coefficients were analyzed as constant or variable throughout the drying process. The diffusive mechanisms of mass transfer were estimated in order to identify the limiting one in drying. According to the results obtained, the vapor flux is controlled by liquid superficial diffusion into the particle. However, it was found that the effective moisture diffusivity is a harmonic mean of all the diffusive mechanisms, being the all type of moisture diffusivity of both particles and the porous medium important parameters in drying. The results showed that the drying of the porous medium studied is controlled by external resistance of heat and mass transfer. The pseudo-homogeneous formulation presented restrictions for the situation in which the interfacial equilibrium is admitted in the drying problem. |
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Perazzini, HugoFreire, José Teixeirahttp://lattes.cnpq.br/2270677706718167http://lattes.cnpq.br/267631154753541423aab8a6-9181-4279-b477-d42f580b0dfd2016-06-02T19:55:39Z2014-07-242016-06-02T19:55:39Z2014-07-18PERAZZINI, Hugo. Secagem de sólidos porosos granulares. 2014. 192 f. Tese (Doutorado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2014.https://repositorio.ufscar.br/handle/ufscar/3949In the present work, an experimental study about heat and mass transfer phenomena was carried out during drying of porous media when subjected to an upward flow of heated air. The cylindrical porous media consisted of non-consolidated particles of activated alumina of several diameters. The particulate system was initially characterized based on the achievement of its main physical, thermal and structural properties. The drying experiments consisted of obtaining sorption isotherms at different operational conditions and in determining moisture and temperature data versus time. The temperature profiles were obtained by thermocouples inserted in the porous body and the moisture content data by the gravimetrical method. The concept of time in series analysis was applied to determine the stationarity of the experimental data. The drying of the porous media was studied theoretically based on the context of the pseudo-homogeneous formulation, which led to the estimation of transport parameters of interest considering two situations: the presence of the external resistance to mass transfer and the interfacial equilibrium condition. The estimated transport coefficients were analyzed as constant or variable throughout the drying process. The diffusive mechanisms of mass transfer were estimated in order to identify the limiting one in drying. According to the results obtained, the vapor flux is controlled by liquid superficial diffusion into the particle. However, it was found that the effective moisture diffusivity is a harmonic mean of all the diffusive mechanisms, being the all type of moisture diffusivity of both particles and the porous medium important parameters in drying. The results showed that the drying of the porous medium studied is controlled by external resistance of heat and mass transfer. The pseudo-homogeneous formulation presented restrictions for the situation in which the interfacial equilibrium is admitted in the drying problem.No presente trabalho, os fenômenos de transferência de calor e massa foram estudados experimentalmente durante a secagem de meios porosos quando submetidos a um escoamento monofásico ascendente de ar aquecido. Os meios porosos estudados foram de geometria cilíndrica e não-consolidados de partículas de alumina ativada de diferentes diâmetros. Preliminarmente, o sistema particulado foi caracterizado com base na obtenção de suas principais propriedades físicas, térmicas e estruturais. Os experimentos de secagem em camada espessa e camada delgada consistiram na obtenção de isotermas de sorção em diferentes condições operacionais e na determinação de dados de temperatura e umidade em função do tempo para um meio poroso insaturado. Os perfis unidirecionais de temperatura foram obtidos a partir de um conjunto de termopares inseridos no corpo poroso, enquanto que dados de umidade do material em função do tempo foram determinados por gravimetria. O conceito da análise de séries temporais foi aplicado para investigar a variação dos dados observados experimentalmente. Paralelamente, o problema de secagem foi estudado teoricamente com base no contexto a uma fase da formulação pseudo-homogênea, o que levou à estimação de parâmetros de transporte de interesse para duas situações distintas: presença da resistência externa à transferência e condição de equilíbrio interfacial. Os coeficientes de transporte foram tratados como constantes ou variáveis ao longo do processo de secagem e verificado o ajuste proporcionado pelo modelo difusivo para essas duas abordagens. Os principais mecanismos difusivos de transferência de massa foram estimados com o intuito de identificar o mecanismo limitante e também se a cinética de secagem é controlada pela difusão na partícula ou nos interstícios do meio poroso. Os resultados obtidos mostraram que a secagem dos meios porosos estudados é controlada pela resistência externa à transferência de calor e massa e que a formulação pseudo-homogênea apresentou restrições para a situação na qual o equilíbrio interfacial é admitido no sistema. Verificou-se que a difusividade efetiva de umidade dos meios porosos é uma média harmônica de todos os mecanismos difusivos existentes, sendo ambas as características das partículas e do meio poroso, importantes no processo de secagem.Universidade Federal de Sao Carlosapplication/pdfporUniversidade Federal de São CarlosPrograma de Pós-Graduação em Engenharia Química - PPGEQUFSCarBRTransferência de calorEngenharia químicaMeios porososQuantidade de movimentoCalor - transmissãoMassa - transferênciaENGENHARIAS::ENGENHARIA QUIMICASecagem de sólidos porosos granularesinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesis-1-12e542afc-9fec-43b4-b11a-1eb2ed3a1f3dinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSCARinstname:Universidade Federal de São Carlos (UFSCAR)instacron:UFSCARORIGINAL5969.pdfapplication/pdf5762637https://repositorio.ufscar.br/bitstream/ufscar/3949/1/5969.pdfb93939ad127db2a63af10c90cac8c992MD51TEXT5969.pdf.txt5969.pdf.txtExtracted texttext/plain0https://repositorio.ufscar.br/bitstream/ufscar/3949/2/5969.pdf.txtd41d8cd98f00b204e9800998ecf8427eMD52THUMBNAIL5969.pdf.jpg5969.pdf.jpgIM Thumbnailimage/jpeg5289https://repositorio.ufscar.br/bitstream/ufscar/3949/3/5969.pdf.jpg9afef203bc2169b5eae074e3561a834fMD53ufscar/39492023-09-18 18:31:33.352oai:repositorio.ufscar.br:ufscar/3949Repositório InstitucionalPUBhttps://repositorio.ufscar.br/oai/requestopendoar:43222023-09-18T18:31:33Repositório Institucional da UFSCAR - Universidade Federal de São Carlos (UFSCAR)false |
dc.title.por.fl_str_mv |
Secagem de sólidos porosos granulares |
title |
Secagem de sólidos porosos granulares |
spellingShingle |
Secagem de sólidos porosos granulares Perazzini, Hugo Transferência de calor Engenharia química Meios porosos Quantidade de movimento Calor - transmissão Massa - transferência ENGENHARIAS::ENGENHARIA QUIMICA |
title_short |
Secagem de sólidos porosos granulares |
title_full |
Secagem de sólidos porosos granulares |
title_fullStr |
Secagem de sólidos porosos granulares |
title_full_unstemmed |
Secagem de sólidos porosos granulares |
title_sort |
Secagem de sólidos porosos granulares |
author |
Perazzini, Hugo |
author_facet |
Perazzini, Hugo |
author_role |
author |
dc.contributor.authorlattes.por.fl_str_mv |
http://lattes.cnpq.br/2676311547535414 |
dc.contributor.author.fl_str_mv |
Perazzini, Hugo |
dc.contributor.advisor1.fl_str_mv |
Freire, José Teixeira |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/2270677706718167 |
dc.contributor.authorID.fl_str_mv |
23aab8a6-9181-4279-b477-d42f580b0dfd |
contributor_str_mv |
Freire, José Teixeira |
dc.subject.por.fl_str_mv |
Transferência de calor Engenharia química Meios porosos Quantidade de movimento Calor - transmissão Massa - transferência |
topic |
Transferência de calor Engenharia química Meios porosos Quantidade de movimento Calor - transmissão Massa - transferência ENGENHARIAS::ENGENHARIA QUIMICA |
dc.subject.cnpq.fl_str_mv |
ENGENHARIAS::ENGENHARIA QUIMICA |
description |
In the present work, an experimental study about heat and mass transfer phenomena was carried out during drying of porous media when subjected to an upward flow of heated air. The cylindrical porous media consisted of non-consolidated particles of activated alumina of several diameters. The particulate system was initially characterized based on the achievement of its main physical, thermal and structural properties. The drying experiments consisted of obtaining sorption isotherms at different operational conditions and in determining moisture and temperature data versus time. The temperature profiles were obtained by thermocouples inserted in the porous body and the moisture content data by the gravimetrical method. The concept of time in series analysis was applied to determine the stationarity of the experimental data. The drying of the porous media was studied theoretically based on the context of the pseudo-homogeneous formulation, which led to the estimation of transport parameters of interest considering two situations: the presence of the external resistance to mass transfer and the interfacial equilibrium condition. The estimated transport coefficients were analyzed as constant or variable throughout the drying process. The diffusive mechanisms of mass transfer were estimated in order to identify the limiting one in drying. According to the results obtained, the vapor flux is controlled by liquid superficial diffusion into the particle. However, it was found that the effective moisture diffusivity is a harmonic mean of all the diffusive mechanisms, being the all type of moisture diffusivity of both particles and the porous medium important parameters in drying. The results showed that the drying of the porous medium studied is controlled by external resistance of heat and mass transfer. The pseudo-homogeneous formulation presented restrictions for the situation in which the interfacial equilibrium is admitted in the drying problem. |
publishDate |
2014 |
dc.date.available.fl_str_mv |
2014-07-24 2016-06-02T19:55:39Z |
dc.date.issued.fl_str_mv |
2014-07-18 |
dc.date.accessioned.fl_str_mv |
2016-06-02T19:55:39Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/doctoralThesis |
format |
doctoralThesis |
status_str |
publishedVersion |
dc.identifier.citation.fl_str_mv |
PERAZZINI, Hugo. Secagem de sólidos porosos granulares. 2014. 192 f. Tese (Doutorado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2014. |
dc.identifier.uri.fl_str_mv |
https://repositorio.ufscar.br/handle/ufscar/3949 |
identifier_str_mv |
PERAZZINI, Hugo. Secagem de sólidos porosos granulares. 2014. 192 f. Tese (Doutorado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2014. |
url |
https://repositorio.ufscar.br/handle/ufscar/3949 |
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openAccess |
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Universidade Federal de São Carlos |
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Programa de Pós-Graduação em Engenharia Química - PPGEQ |
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UFSCar |
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BR |
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