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Authors
Abstract(s)
A necessidade de racionalização do consumo de energia no setor da indústria agroalimentar tem
remetido para o desenvolvimento de metodologias que promovam a melhoria do desempenho
energético destas instalações, pois do ponto de vista do consumo de energia e da garantia da
segurança alimentar são assuntos de extrema importância e que devem ser estudados tendo em
vista a sua melhoria.
A dinâmica de fluidos computacional (DFC) tornou-se uma técnica que progressivamente tem
vindo a ser adotada pela Engenharia devido às suas potencialidades em modelar escoamentos
de fluidos com transferência de calor e massa em processos industriais, conseguindo-se usualmente
realizar uma análise detalhada do processo físico sem os custos associados a uma análise
experimental.
O presente estudo tem como principal objetivo a avaliação da influência dos ciclos de abertura
e fecho de duas tipologias de portas (de dobradiças ou de correr) no escoamento de ar, nomeadamente
nas infiltrações de ar, e no campo de temperaturas do espaço refrigerado. No sentido
de avaliar a influência destes ciclos de abertura e fecho de portas, foi realizada uma análise de
sensibilidade variando a temperatura no exterior do espaço refrigerado para ambas as tipologias
de porta, e um estudo comparativo de modo a avaliar qual das tipologias de porta apresenta um
melhor desempenho do ponto de vista da minimização da infiltração de ar.
O estudo comporta uma análise computacional tridimensional e em regime transiente por DFC,
que possibilita a avaliação do escoamento de ar em cada passo de tempo e, deste modo, aferir
qual a influência da variação que a temperatura no exterior da câmara de refrigeração tem, na
interação térmica entre os dois ambientes.
As previsões numéricas obtidas, indicam que a temperatura do ar no exterior do espaço refrigerado
influencia a infiltração de ar e, consequentemente, a sua temperatura média no interior
da câmara. Significa que, quanto maior for a diferença de temperatura entre os dois ambientes
maior será a infiltração de ar, e como tal, maior será a temperatura média deste no interior da
câmara. Relativamente, à comparação dos dois tipos de porta verifica-se que do ponto de vista
da minimização da infiltração de ar, a porta de correr apresenta um melhor desempenho que a
porta de dobradiças.
O conhecimento da evolução da infiltração de ar durante o ciclo de abertura/ fecho de porta,
permite tirar algumas ilações acerca da sua influência nas condições do ar no interior do espaço
refrigerado. Sendo assim possível indicar algumas sugestões de melhoria que visam a racionalização
do consumo de energia.
The need of rationalizate the energy consumption in food industry sector has fasten the development of methodologies whose objective is to promote the improvement of the energy performance of the facilities, due to its extreme relevance in what concerns energy consumption and ensuring food safety. Thus, these conditions should be studied in order to improve them. Computational fluid dynamics (CFD) has become a technique that has been progressively adopted by engineering due to its capabilities to model fluid flow with heat and mass transfer in industrial processes, usually becoming able to perform a detailed analysis of physical process without the costs associated with an experimental analysis. The aim of this study is to evaluate the influence in air flow of opening and closing cycles of two types of doors (hinged and sliding), particularly in air leaks, and in the temperature field inside the cold room. In order to evaluate the influence of these cycles, a sensivity analysis by varying the temperature outside the cold room for both types of door was performed. Additionaly, was performed a comparative study to evaluate which type of doors has a better performance in terms of minimizing air infiltration. The study comprises a three-dimensional computational and transient analysis by CFD, which at every time step allows the evaluation of air flow, and thereby ascertain the influence of temperature variation outside the cold room has in thermal interaction between the two sides of cold room. The numerical predictions indicate that the temperature of the air outside the cold room affects the air infiltration and, consequently, the average temperature of air inside the cold room. This condition means that greater the difference of air temperature between the two sides of the cold room greater is, greater will be the infiltration rate, and thus, greater will be the average temperature of the air inside the cold room. Relatively to the comparison of the two type of doors, it is verified that sliding door has a better performance than hinged door due to the lower infiltration rate. The knowledge about the evolution of the air infiltration during the door opening/closing time, allows to draw some conclusions about its influence on the air conditions inside the cold room. So it is possible to indicate some improvement suggestions that promote the energy consumption rationalization.
The need of rationalizate the energy consumption in food industry sector has fasten the development of methodologies whose objective is to promote the improvement of the energy performance of the facilities, due to its extreme relevance in what concerns energy consumption and ensuring food safety. Thus, these conditions should be studied in order to improve them. Computational fluid dynamics (CFD) has become a technique that has been progressively adopted by engineering due to its capabilities to model fluid flow with heat and mass transfer in industrial processes, usually becoming able to perform a detailed analysis of physical process without the costs associated with an experimental analysis. The aim of this study is to evaluate the influence in air flow of opening and closing cycles of two types of doors (hinged and sliding), particularly in air leaks, and in the temperature field inside the cold room. In order to evaluate the influence of these cycles, a sensivity analysis by varying the temperature outside the cold room for both types of door was performed. Additionaly, was performed a comparative study to evaluate which type of doors has a better performance in terms of minimizing air infiltration. The study comprises a three-dimensional computational and transient analysis by CFD, which at every time step allows the evaluation of air flow, and thereby ascertain the influence of temperature variation outside the cold room has in thermal interaction between the two sides of cold room. The numerical predictions indicate that the temperature of the air outside the cold room affects the air infiltration and, consequently, the average temperature of air inside the cold room. This condition means that greater the difference of air temperature between the two sides of the cold room greater is, greater will be the infiltration rate, and thus, greater will be the average temperature of the air inside the cold room. Relatively to the comparison of the two type of doors, it is verified that sliding door has a better performance than hinged door due to the lower infiltration rate. The knowledge about the evolution of the air infiltration during the door opening/closing time, allows to draw some conclusions about its influence on the air conditions inside the cold room. So it is possible to indicate some improvement suggestions that promote the energy consumption rationalization.
Description
Keywords
Análise de Sensibilidade. Câmara de Refrigeração Desempenho Térmico Dinâmica de Fluidos Computacional Infiltração Modelação Numérica Tipologia de Portas