Desenvolvimento de um sistema de secagem utilizando aquecimento solar
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Data
2022-07-13
Autores
Predolin, Rodrigo Eduardo
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Muitos alimentos apresentam um acelerado processo de deterioração. Visando reduzir esta ve- locidade de deterioração, diversas técnicas de conservação foram desenvolvidas ao longo do tempo; como, por exemplo, o processo de desidratação de alimentos, que apresenta compara- tivamente uma alta eficácia. Os benefícios da desidratação dos alimentos são a preservação do produto e a redução do seu peso, que tem como consequência a redução no custo de transporte e no armazenamento, além de criar condições desfavoráveis para o desenvolvimento de micro- organismos. Com foco na desidratação de produtos, foi desenvolvido e analisado um secador solar indireto com convecção natural. O equipamento é composto por 3 partes principais: a placa absorvedora com 0,5 m2 de área superficial, a câmara de secagem e o duto de saída de gases, destacando que a placa absorvedora tem duas posições de trabalho. A análise do equi- pamento se utilizou de uma instrumentação, que foi constituída dos sensores de temperatura, umidade e pressão atmosférica, posicionados na entrada e na saída de ar no equipamento, além do anemômetro tipo turbina na saída de ar e a célula de carga na câmara de secagem para registrar a remoção da umidade, a qual é determinada também pelo balanço de massa realizado com os dados dos sensores na entrada e na saída do ar no equipamento. A análise térmica da placa absorvedora é realizada com a presença de 3 sensores de temperatura posicionados na face inferior da placa de forma espaçada ao longo de seu comprimento. Para visualizar o campo velocidade e temperatura no interior do equipamento, foi elaborada a simulação numérica, uti- lizando as dimensões reais do equipamento na geração da malha. Os dados registrados pelos sensores para o dia em análise no experimento foram utilizados como condições de contorno na simulação e a análise dos seus resultados ocorreram para a temperatura e vazão de ar na saída do equipamento, comparando os valores obtidos no experimento com a simulação. A alteração no posicionamento da placa absorvedora aumentou a taxa de remoção de umidade de 0,47 g/- min para 0,56 g/min e a remoção total de umidade ao londo do dia se alterou de 185 g para 220 g, com a eficiência térmica média diária se alterando de 8,5% para 19,8%.
Many foods have an accelerated deterioration process. In order to reduce this speed of dete- rioration, several conservation techniques have been developed over time; such as, for example, the food dehydration process, which is comparatively highly effective. The benefits of food de- hydration are the preservation of the product and the reduction of its weight, which results in a reduction in the cost of transport and storage, in addition to creating unfavorable conditions for the development of microorganisms. Focusing on product dehydration, an indirect solar dryer with natural convection was developed and analyzed. The equipment consists of 3 main parts: the absorber plate with a surface area of 0.5 m2 , the drying chamber and the gas outlet duct, noting that the absorber plate has two working positions. The analysis of the equipment used an instrumentation, which consisted of temperature, humidity and atmospheric pressure sensors, positioned at the inlet and outlet of the air in the equipment, in addition to the turbine-type anemometer in the air outlet and the load cell in the chamber. Drying process to record the removal of moisture, which is also determined by the mass balance performed with the data from the sensors at the inlet and outlet of the air in the equipment. The thermal analysis of the absorber plate is performed with the presence of 3 temperature sensors positioned on the underside of the plate spaced along its length. In order to visualize the velocity and temperature field inside the equipment, a numerical simulation was elaborated, using the real dimensions of the equipment in the generation of the mesh. The data recorded by the sensors for the day under analysis in the experiment were used as boundary conditions in the simulation and the analysis of their results took place for the temperature and air flow at the outlet of the equip- ment, comparing the values obtained in the experiment with the simulation. The change in the position of the absorber plate increased the moisture removal rate from 0.47 g/min to 0.56 g/min and the total moisture removal throughout the day changed from 185 g to 220 g, with the efficiency daily average temperature changing from 8.5% to 19.8%.
Many foods have an accelerated deterioration process. In order to reduce this speed of dete- rioration, several conservation techniques have been developed over time; such as, for example, the food dehydration process, which is comparatively highly effective. The benefits of food de- hydration are the preservation of the product and the reduction of its weight, which results in a reduction in the cost of transport and storage, in addition to creating unfavorable conditions for the development of microorganisms. Focusing on product dehydration, an indirect solar dryer with natural convection was developed and analyzed. The equipment consists of 3 main parts: the absorber plate with a surface area of 0.5 m2 , the drying chamber and the gas outlet duct, noting that the absorber plate has two working positions. The analysis of the equipment used an instrumentation, which consisted of temperature, humidity and atmospheric pressure sensors, positioned at the inlet and outlet of the air in the equipment, in addition to the turbine-type anemometer in the air outlet and the load cell in the chamber. Drying process to record the removal of moisture, which is also determined by the mass balance performed with the data from the sensors at the inlet and outlet of the air in the equipment. The thermal analysis of the absorber plate is performed with the presence of 3 temperature sensors positioned on the underside of the plate spaced along its length. In order to visualize the velocity and temperature field inside the equipment, a numerical simulation was elaborated, using the real dimensions of the equipment in the generation of the mesh. The data recorded by the sensors for the day under analysis in the experiment were used as boundary conditions in the simulation and the analysis of their results took place for the temperature and air flow at the outlet of the equip- ment, comparing the values obtained in the experiment with the simulation. The change in the position of the absorber plate increased the moisture removal rate from 0.47 g/min to 0.56 g/min and the total moisture removal throughout the day changed from 185 g to 220 g, with the efficiency daily average temperature changing from 8.5% to 19.8%.
Descrição
Palavras-chave
Eficiência solar, Placa solar absorvedora, Secador solar de convecção, Secador solar indireto, Indirect solar dryer, Solar absorber panel, Convective solar dryer, Thermal efficiency