Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado
Autor(a) principal: | |
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Data de Publicação: | 2015 |
Tipo de documento: | Dissertação |
Idioma: | por |
Título da fonte: | Repositório Institucional da UNESP |
Texto Completo: | http://hdl.handle.net/11449/127954 http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/02-09-2015/000847749.pdf |
Resumo: | This work presents a numerical model to simulate the steady and transient flow and heat transfer between the refrigerant fluid and outside air along tube-fin evaporators commonly used in 'no-frost' household refrigerators. The refrigerant flow inside the tube is taken as one- dimensional and divided in a two-phase flow region and a superheated vapor flow region. The refrigerant pressure drop and the moisture condensation on the airflow crossing the outside of the tubes are taken into account. The homogeneous flow model is employed for the two-phase flow region. The fundamental equations of mass conservation, momentum and energy conservation governing the refrigerant flow are solved in order to evaluate the velocity, pressure and specific enthalpy of the refrigerant fluid. The energy and mass (humidity) conservation equations for the air flow are solved in order to evaluate the temperature and absolute humidity of the air crossing the evaporator, respectively. The energy conservation equation for the evaporator tube wall is also solved to obtain the wall temperature distribution. Furthermore, the model needs closer constitutive equations to calculate the friction coefficients, the refrigerant and air heat transfer coefficients, the water mass transfer coefficient and the refrigerant, air and water thermo-physical properties. The governing equations are integrated numerically using Euler's method and the resulting algebraic system of equations is solved by Newton-Raphson's method. The model could be used to: (a) determine evaporator performance parameters, such as: refrigeration load; outlet refrigerant and air temperatures; among others, since the evaporator operating conditions and dimensions are known. In this case a direct problem is solved from a set of inlet conditions for the refrigerant and also for the air; (b) determine the refrigerant mass flow rate along evaporator tubes, once its ... |
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Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletadoEvaporadoresRefrigeradoresEscoamento bifasicoRefrigeratorsThis work presents a numerical model to simulate the steady and transient flow and heat transfer between the refrigerant fluid and outside air along tube-fin evaporators commonly used in 'no-frost' household refrigerators. The refrigerant flow inside the tube is taken as one- dimensional and divided in a two-phase flow region and a superheated vapor flow region. The refrigerant pressure drop and the moisture condensation on the airflow crossing the outside of the tubes are taken into account. The homogeneous flow model is employed for the two-phase flow region. The fundamental equations of mass conservation, momentum and energy conservation governing the refrigerant flow are solved in order to evaluate the velocity, pressure and specific enthalpy of the refrigerant fluid. The energy and mass (humidity) conservation equations for the air flow are solved in order to evaluate the temperature and absolute humidity of the air crossing the evaporator, respectively. The energy conservation equation for the evaporator tube wall is also solved to obtain the wall temperature distribution. Furthermore, the model needs closer constitutive equations to calculate the friction coefficients, the refrigerant and air heat transfer coefficients, the water mass transfer coefficient and the refrigerant, air and water thermo-physical properties. The governing equations are integrated numerically using Euler's method and the resulting algebraic system of equations is solved by Newton-Raphson's method. The model could be used to: (a) determine evaporator performance parameters, such as: refrigeration load; outlet refrigerant and air temperatures; among others, since the evaporator operating conditions and dimensions are known. In this case a direct problem is solved from a set of inlet conditions for the refrigerant and also for the air; (b) determine the refrigerant mass flow rate along evaporator tubes, once its ...Neste trabalho apresenta-se um modelo numérico para simular o escoamento e a transferência de calor entre o fluido refrigerante e ar externo em regime permanente e transiente ao longo de evaporadores de tubos aletados comumente usados em refrigeradores domésticos do tipo frost-free e sistemas de ar condicionado. O escoamento do fluido refrigerante é dividido em duas regiões: uma de escoamento bifásico e outra de vapor superaquecido. Considera-se a queda de pressão do escoamento no interior dos tubos e a condensação do vapor d'água do ar úmido que escoa em fluxo cruzado na parte externa dos tubos. O escoamento bifásico é analisado segundo o modelo homogêneo. As equações fundamentais de conservação da massa, da quantidade de movimento e de conservação da energia que governam o escoamento do refrigerante são resolvidas, respectivamente, para o cálculo da velocidade, da pressão e da entalpia específica do fluido refrigerante. Para o escoamento de ar, são resolvidas as equações de conservação da energia e de conservação da massa (umidade). Resolve-se, também, a equação da conservação da energia para a parede do tubo, para obter sua distribuição de temperatura. O modelo necessita ainda de equações constitutivas para o cálculo dos: fatores de atrito, coeficientes de transferência de calor para o ar e para o refrigerante, do coeficiente transferência de massa para a água e das propriedades termofísicas do refrigerante, do ar e da água. As equações governantes são integradas numericamente usando o método de Euler e o sistema de equações algébricas resultante é solucionado pelo método de Newton-Raphson. O modelo pode ser usado para: (a) determinar os parâmetros de desempenho do evaporador, tais como: capacidade de refrigeração, temperaturas de saída do refrigerante e do ar, dentre outros, desde que as condições de operação e os parâmetros geométricos...Universidade Estadual Paulista (Unesp)Seixlack, André Luiz [UNESP]Universidade Estadual Paulista (Unesp)Pimenta, Paulo Henrique Neves [UNESP]2015-09-17T15:26:48Z2015-09-17T15:26:48Z2015-06-29info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesis130 f. : il.application/pdfPIMENTA, Paulo Henrique Neves. Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado. 2015. 130 f. Dissertação (mestrado) - Universidade Estadual Paulista Júlio de Mesquita Filho, Faculdade de Engenharia, 2015.http://hdl.handle.net/11449/127954000847749http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/02-09-2015/000847749.pdf33004099082P28658860438651895Alephreponame:Repositório Institucional da UNESPinstname:Universidade Estadual Paulista (UNESP)instacron:UNESPporinfo:eu-repo/semantics/openAccess2024-08-05T18:16:17Zoai:repositorio.unesp.br:11449/127954Repositório InstitucionalPUBhttp://repositorio.unesp.br/oai/requestopendoar:29462024-08-05T18:16:17Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP)false |
dc.title.none.fl_str_mv |
Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado |
title |
Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado |
spellingShingle |
Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado Pimenta, Paulo Henrique Neves [UNESP] Evaporadores Refrigeradores Escoamento bifasico Refrigerators |
title_short |
Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado |
title_full |
Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado |
title_fullStr |
Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado |
title_full_unstemmed |
Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado |
title_sort |
Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado |
author |
Pimenta, Paulo Henrique Neves [UNESP] |
author_facet |
Pimenta, Paulo Henrique Neves [UNESP] |
author_role |
author |
dc.contributor.none.fl_str_mv |
Seixlack, André Luiz [UNESP] Universidade Estadual Paulista (Unesp) |
dc.contributor.author.fl_str_mv |
Pimenta, Paulo Henrique Neves [UNESP] |
dc.subject.por.fl_str_mv |
Evaporadores Refrigeradores Escoamento bifasico Refrigerators |
topic |
Evaporadores Refrigeradores Escoamento bifasico Refrigerators |
description |
This work presents a numerical model to simulate the steady and transient flow and heat transfer between the refrigerant fluid and outside air along tube-fin evaporators commonly used in 'no-frost' household refrigerators. The refrigerant flow inside the tube is taken as one- dimensional and divided in a two-phase flow region and a superheated vapor flow region. The refrigerant pressure drop and the moisture condensation on the airflow crossing the outside of the tubes are taken into account. The homogeneous flow model is employed for the two-phase flow region. The fundamental equations of mass conservation, momentum and energy conservation governing the refrigerant flow are solved in order to evaluate the velocity, pressure and specific enthalpy of the refrigerant fluid. The energy and mass (humidity) conservation equations for the air flow are solved in order to evaluate the temperature and absolute humidity of the air crossing the evaporator, respectively. The energy conservation equation for the evaporator tube wall is also solved to obtain the wall temperature distribution. Furthermore, the model needs closer constitutive equations to calculate the friction coefficients, the refrigerant and air heat transfer coefficients, the water mass transfer coefficient and the refrigerant, air and water thermo-physical properties. The governing equations are integrated numerically using Euler's method and the resulting algebraic system of equations is solved by Newton-Raphson's method. The model could be used to: (a) determine evaporator performance parameters, such as: refrigeration load; outlet refrigerant and air temperatures; among others, since the evaporator operating conditions and dimensions are known. In this case a direct problem is solved from a set of inlet conditions for the refrigerant and also for the air; (b) determine the refrigerant mass flow rate along evaporator tubes, once its ... |
publishDate |
2015 |
dc.date.none.fl_str_mv |
2015-09-17T15:26:48Z 2015-09-17T15:26:48Z 2015-06-29 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/masterThesis |
format |
masterThesis |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
PIMENTA, Paulo Henrique Neves. Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado. 2015. 130 f. Dissertação (mestrado) - Universidade Estadual Paulista Júlio de Mesquita Filho, Faculdade de Engenharia, 2015. http://hdl.handle.net/11449/127954 000847749 http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/02-09-2015/000847749.pdf 33004099082P2 8658860438651895 |
identifier_str_mv |
PIMENTA, Paulo Henrique Neves. Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado. 2015. 130 f. Dissertação (mestrado) - Universidade Estadual Paulista Júlio de Mesquita Filho, Faculdade de Engenharia, 2015. 000847749 33004099082P2 8658860438651895 |
url |
http://hdl.handle.net/11449/127954 http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/02-09-2015/000847749.pdf |
dc.language.iso.fl_str_mv |
por |
language |
por |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
130 f. : il. application/pdf |
dc.publisher.none.fl_str_mv |
Universidade Estadual Paulista (Unesp) |
publisher.none.fl_str_mv |
Universidade Estadual Paulista (Unesp) |
dc.source.none.fl_str_mv |
Aleph reponame:Repositório Institucional da UNESP instname:Universidade Estadual Paulista (UNESP) instacron:UNESP |
instname_str |
Universidade Estadual Paulista (UNESP) |
instacron_str |
UNESP |
institution |
UNESP |
reponame_str |
Repositório Institucional da UNESP |
collection |
Repositório Institucional da UNESP |
repository.name.fl_str_mv |
Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP) |
repository.mail.fl_str_mv |
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_version_ |
1808128182704930816 |