Diseño de un secador para café mediante el calentamientos del aire en dos etapas utilizando energía solar
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2015
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El objetivo principal del proyecto fue diseñar un sistema de secado de café que afecte lo menos posible la calidad del grano y que partiera de energías renovables para reducir la huella ecológica y destacarse en el mercado internacional del café gourmet. El fundamento técnico fue aprovechar la energía solar disponible para aumentar la temperatura del aire de secado y reducir su humedad relativa, esto en dos etapas: primero en un colector solar de aire y luego en una cámara de secado para deshumidificar el grano de café y reducir su contenido de humedad en base húmeda desde un 53 % hasta un 12 %, valor establecido por el Instituto Costarricense del Café (ICAFE). Con el diseño de la cámara de secado se logró no maltratar el grano ni exponerlo a la contaminación del medio. Además, su velocidad de deshumidificación no se ve forzada ni acelerada. Los principales resultados fueron una disminución del 60 % del espacio requerido para secar el café en comparación con el método en patios de concreto, pasando de 322 m2 a 132 m2, y un aumento del 58 % de la disponibilidad energética para el secado (entalpía del aire), que aumentó de 62,4 kJ/kg a 98,5 kJ/kg. En el análisis económico para la viabilidad del proyecto se consideró un aumento de 60 % de la producción con un precio de venta de $225,00/quintal de café y una utilidad del 25 %, una inversión de $40 000,00 y un período de depreciación lineal de 10 años sin valor de rescate, dando como resultado una tasa interna de retorno (TIR) de 86,8 % y un valor actual neto (VAN) de $131 337,10.
The main objective of this project was to design a coffee drying system using renewable energy as a primary source in order to reduce the ecological footprint affecting, as less as posible, the quality of the bean and to make it stand up in the gourmet coffee international market. The technical foundation was to use the available solar energy to increase the temperature of the drying air and reduce it’s relative humidity, in two stages: first, in a solar air collector and then in a drying chamber to dehumidify the beans as well to reduce its humidity content in humid base from 53% to 12%, this parameter was established by the Instituto Costarricense del Café (ICAFE) for it’s name in spanish. With the design of the drying chamber was posible not to damage the bean or exposed it to the environmental pollution. Furthermore, the dehumidifying speed of the bean was not affected in any way: forced nor accelerated. The main results were a 60% reduction of the space requiered to dry the coffee using the concrete patios method, decreasing from 322 m2 to 132 m2 , and a 58% increase of energetic availability for the drying process (enthalpy of the air) which increases from 62,4 kJ/kg to 98,5 kJ/kg. For the viability of the Project a 60% increase in production was considered, with a sale Price of $225,00/quintal of coffee; also a 25% of utility, a $40 000,00 investment and a linear depreciaton period of 10 years with no surrender value were considered. As a result, an internal return ratio (IRR) of 86.8% and a net present value (VAN) of $131 337,10 were obtained.
The main objective of this project was to design a coffee drying system using renewable energy as a primary source in order to reduce the ecological footprint affecting, as less as posible, the quality of the bean and to make it stand up in the gourmet coffee international market. The technical foundation was to use the available solar energy to increase the temperature of the drying air and reduce it’s relative humidity, in two stages: first, in a solar air collector and then in a drying chamber to dehumidify the beans as well to reduce its humidity content in humid base from 53% to 12%, this parameter was established by the Instituto Costarricense del Café (ICAFE) for it’s name in spanish. With the design of the drying chamber was posible not to damage the bean or exposed it to the environmental pollution. Furthermore, the dehumidifying speed of the bean was not affected in any way: forced nor accelerated. The main results were a 60% reduction of the space requiered to dry the coffee using the concrete patios method, decreasing from 322 m2 to 132 m2 , and a 58% increase of energetic availability for the drying process (enthalpy of the air) which increases from 62,4 kJ/kg to 98,5 kJ/kg. For the viability of the Project a 60% increase in production was considered, with a sale Price of $225,00/quintal of coffee; also a 25% of utility, a $40 000,00 investment and a linear depreciaton period of 10 years with no surrender value were considered. As a result, an internal return ratio (IRR) of 86.8% and a net present value (VAN) of $131 337,10 were obtained.
Descripción
Proyecto de graduación (licenciatura en ingeniería mecánica)--Universidad de Costa Rica. Facultad de Ingeniería. Escuela de Ingeniería Mecánica, 2015
Palabras clave
ANALISIS FINANCIERO, BENEFICIO DE CAFE, CAFE - SECADO, DISEÑO DE MAQUINAS, ENERGIA SOLAR - APLICACIONES INDUSTRIALES - COSTA RICA, SECADORES SOLARES - DISEÑO Y CONSTRUCCION