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Efeito da variação do comprimento do dissipador de calor de um EGR Cooler quando sujeito a diferentes carregamentos
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Resumo(s)
A preocupação ambiental e a escassez dos recursos naturais da Terra, são nos
dias de hoje um dos temas mais ativos da sociedade. Os fabricantes de automóveis
encontram-se assim empenhados em implementar tecnologias que reduzam a sua
pegada ecológica, como a aplicação do dispositivo Exhaust Gas Recirculation
(EGR) Cooler que visa diminuir os níveis de emissão de NOx.
A tecnologia supramencionada é, no entanto, sujeita a condições de trabalho
extremas que podem comprometer o seu desempenho e durabilidade. Este dispositivo
é assim alvo de um aperfeiçoamento contínuo a fim de corresponder
às expectativas, pelo que neste estudo será avaliado o impacto que a variação
do comprimento dos dissipadores internos tem nas tensões térmicas induzidas e
restantes carregamentos, e como estes afetam o seu desempenho.
Este estudo revelou que a variação do comprimento do dissipador interno
afeta cada uma das cargas de forma distinta. A redução da distância entre o
dissipador e a base da câmara de refrigeração permite melhorar a transferência
de calor do EGR, mas em contrapartida aumenta as tensões térmicas induzidas
pelas altas temperaturas dos gases, o que se traduz numa redução da vida útil
deste dispositivo.
Por fim, o aumento do comprimento, é também vantajoso ao nível da primeira
frequência natural do sistema, uma vez que implica o aumento deste valor face
ao acréscimo da rigidez.
Environmental concern and the decline of Earth’s natural resources are one of the most active issues in today’s society. Aiming to reduce their environmental footprint, car manufacturers have chosen to install a technology called Exhaust Gas recirculation (EGR) Cooler in their vehicles, as this is a versatile and effective technique for reducing NOx emissions. This technology requires to take into consideration different factors, such as high gas temperatures, mechanical vibrations and others loads during the design phase, as this may affect its performance and durability. The purpose of this study is then evaluate the impact that varying the length of the inner fins has on the induced thermal stress and remaining loads, and how these affect its EGR. This research revealed that varying the length of the internal fin affects each of the loads differently. Reducing the distance between the fin and the baffle allows improving the heat transfer of the EGR, but in return increases the thermal stresses induced by the high gas temperatures, which translates into a reduction in the life of this device. Finally, the increase in length is also advantageous in terms of the first natural frequency of the system, since it implies the increase of this value due to the increased stiffness.
Environmental concern and the decline of Earth’s natural resources are one of the most active issues in today’s society. Aiming to reduce their environmental footprint, car manufacturers have chosen to install a technology called Exhaust Gas recirculation (EGR) Cooler in their vehicles, as this is a versatile and effective technique for reducing NOx emissions. This technology requires to take into consideration different factors, such as high gas temperatures, mechanical vibrations and others loads during the design phase, as this may affect its performance and durability. The purpose of this study is then evaluate the impact that varying the length of the inner fins has on the induced thermal stress and remaining loads, and how these affect its EGR. This research revealed that varying the length of the internal fin affects each of the loads differently. Reducing the distance between the fin and the baffle allows improving the heat transfer of the EGR, but in return increases the thermal stresses induced by the high gas temperatures, which translates into a reduction in the life of this device. Finally, the increase in length is also advantageous in terms of the first natural frequency of the system, since it implies the increase of this value due to the increased stiffness.
Descrição
Palavras-chave
Exhaust Gas Recirculation Método dos Elementos Finitos Método dos Volumes Finitos Solidworks Simulation