Methodology for the design of a thermal energy storage module for a solar tunnel dryer using phase change materials (PCM)
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Universidad Industrial de Santander
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El creciente interés en las energías renovables ha abierto una oportunidad para aplicar esta tecnología en la industria y el sector nacional. Sin embargo, en sistemas basados en energía solar, las limitaciones asociadas con la entrega de energía intermitente pueden causar un rendimiento inestable y diseños poco confiables. Las fluctuaciones climáticas, como la velocidad del viento y la apariencia de las nubes, se consideran los principales factores que contribuyen a la inestabilidad en la cantidad de energía disponible. En la agricultura, por ejemplo, el uso de la energía solar térmica aplicada a los sistemas de secado es altamente deseable ya que el proceso es energéticamente intensivo. Por lo tanto, es factible diseñar dispositivos de secado para productos agrícolas, con retornos económicos importantes debido al ahorro de energía y al valor agregado de los materiales procesados. Por lo tanto, el rendimiento energético de los sistemas que funcionan con energía solar térmica se puede mejorar mediante la introducción de un sistema de acumulación de energía basado en el uso de materiales de cambio de fase (PCM). Se presenta la metodología detallada para el diseño de un sistema de acumulación de energía térmica para un secador de túnel tipo Hohenheim para productos agrícolas. Como PCM, se elige parafina porque su temperatura de fusión es cercana a 60 ° C, que es un valor apropiado para la temperatura de secado de este tipo de productos. Los cálculos teóricos muestran que el valor de la temperatura superficial tiene una influencia importante en los cálculos de cambio de fase y la masa total de PCM requerida en el sistema. Por otro lado, la transferencia de calor está dominada por la transferencia de calor externa en el aire. Además, el diámetro del tubo afecta significativamente el tiempo de cambio de fase. Los resultados obtenidos son importantes y aportan una contribución significativa al conocimiento requerido para implementaciones de sistemas similares, ya que se ha explorado poco en este campo en regiones donde las condiciones climáticas son adecuadas para cambios inesperados. El diseño debe implementarse en un prototipo experimental de secador Hohenheim y su rendimiento debe determinarse en función de la medición del cambio de energía del aire de secado.
The increasing interest in renewable energy has opened an opportunity to apply this technology in the industry and domestic sector. However, in solar-based systems, limitations associated with the intermittent energy delivery can cause unstable performance and unreliable designs. Weather fluctuations, such as wind speed and appearance of clouds, are considered the principal factors that contribute to the instability in the amount of energy available. In the agriculture, for instance, the use of thermal solar energy applied to dryer systems is highly desirable since the process is energetically very intensive. Therefore, it is feasible to design dryer devices for agricultural products, with important economic returns due to energy savings and the value added to the materials processed. Thus, the energy performance of systems that operate with solar thermal energy can be improved by introducing an energy accumulation system based on the use of phase change materials (PCM). The detailed methodology for the design of a thermal energy accumulation system for a tunnel dryer type Hohenheim for agricultural products is presented. As PCM, paraffin is chosen because its melting temperature is near 60 °C, which is an appropriate value for the drying temperature of this kind of products. The theoretical calculations show that the value of the surface temperature has an important influence on phase change calculations and the total mass of PCM required in the system. On the other hand, the heat transfer is dominated by the external heat transfer in the air. Additionally, the tube diameter significantly affects the phase change time. The results obtained are important and make a significant contribution to the knowledge required for implementations of similar systems, since little has been explored in this field in regions where the weather conditions are suitable to unexpected changes. The design should be implemented in an experimental prototype of Hohenheim dryer and its performance is to be determined based on measurement of the energy change of the drying air.
The increasing interest in renewable energy has opened an opportunity to apply this technology in the industry and domestic sector. However, in solar-based systems, limitations associated with the intermittent energy delivery can cause unstable performance and unreliable designs. Weather fluctuations, such as wind speed and appearance of clouds, are considered the principal factors that contribute to the instability in the amount of energy available. In the agriculture, for instance, the use of thermal solar energy applied to dryer systems is highly desirable since the process is energetically very intensive. Therefore, it is feasible to design dryer devices for agricultural products, with important economic returns due to energy savings and the value added to the materials processed. Thus, the energy performance of systems that operate with solar thermal energy can be improved by introducing an energy accumulation system based on the use of phase change materials (PCM). The detailed methodology for the design of a thermal energy accumulation system for a tunnel dryer type Hohenheim for agricultural products is presented. As PCM, paraffin is chosen because its melting temperature is near 60 °C, which is an appropriate value for the drying temperature of this kind of products. The theoretical calculations show that the value of the surface temperature has an important influence on phase change calculations and the total mass of PCM required in the system. On the other hand, the heat transfer is dominated by the external heat transfer in the air. Additionally, the tube diameter significantly affects the phase change time. The results obtained are important and make a significant contribution to the knowledge required for implementations of similar systems, since little has been explored in this field in regions where the weather conditions are suitable to unexpected changes. The design should be implemented in an experimental prototype of Hohenheim dryer and its performance is to be determined based on measurement of the energy change of the drying air.
Keywords
solar dryer, Renewable energy, PCM, heat transfer, Energía renovable, secador solar, PCM, transferencia de calor