• Energy Research

The aim of this first part of the study was to estimate the greenhouse gas (GHG) emission and fixation balance in specialty coffee production in the Department of Antioquia, Colombia. The results show that an average of 1,068 kg CO2 per kg of coffee cherry produced is fixed. The fixation and emission balance was positive of 0.271 kg CO2e / kg coffee cherry. Total GHG emission was 0,816 kg CO2e per kg coffee cherry. Emissions due to loss of carbon from soil organic matter, organic matter incorporation and coffee leaf litter decomposition, were 84.3% of total emissions and the remaining 15.7% was due to emissions from nitrogen fertilization.

This study aimed to compare the bioclimate and energy consumption of two coffee wet processing facilities in Colombia, with two typical types of Colombian coffee, using computer simulation. Specifically, we evaluated the effect of the heat generated by machines and the effect of the natural ventilation area on temperature and relative air humidity inside these buildings and their energy consumption. The postharvest plant with typology b gave the best results in terms of temperature and relative humidity suitable to preserve the quality of the coffee bean. Its approximate energy consumption was 30% of the total consumed by typology a.

A comparison between commercial cellulose evaporative cooling pad and pads manufactured with three alternative materials was made for environmental conditions typical of tropical countries. Wind tunnel tests were carried out to compute the convective heat and mass transfer coefficients and to measure the pressure drop across each pad, obtaining expressions that can be used as reference for future simulations. Using a mathematical model, a detailed analysis of the efficiency, Temperature–Humidity Index, temperature drop and relative humidity through the pads was performed in terms of different operative and constructive conditions, such as air velocities, dry-bulb temperatures, relative humidity and pad thickness. Significant differences between the pressure drop across the pads were found, which increases with the inlet air velocity and water flow. A weak relation between the analysed variables and the inlet air velocity was found, while a high correlation between the analysed variables, pad thickness and the external environmental conditions was established. Cooling efficiencies above 40% and a Temperature–Humidity Index below the mild zone of thermal stress were obtained for the alternative panels. Although the cellulose cooling pad showed the best behaviour in all aspects, the alternative pads can be used as substituted in specific applications to reduce the Temperature–Humidity Index inside agricultural facilities.

Este estudio tuvo como objetivo encontrar el área mínima de ventilación natural necesaria para instalaciones de beneficio húmedo de café con secado mecánico en su interior, con el fin de preservar la calidad de café a través de un ambiente bioclimático que propicie la inocuidad biológica, este estudio se realizó con ayuda de simulaciones computacionales en el programa EnergyPlusTM. Se encontró que a medida que se incrementa la capacidad de secado, y por ende la potencia de las máquinas de secado, la temperatura y la humedad relativa interna tienden a aumentar. Por otra parte, se encontró una correlación lineal inversa entre el área de ventilación natural y las variables temperatura y humedad relativa. Por último, se encontraron relaciones de área mínima de ventilación natural con la capacidad de secado, con el fin de obtener un ambiente bioclimático adecuado para la preservación del café pergamino.

Air quality is one of the main factors that must be guaranteed in animal production. However, the measurement of pollutants is still a problem in several countries because the available methods are costly and do not always apply to the reality of the constructive typology adopted, as in countries with a hot climate, which adopt predominantly open facilities. Thus, the objective of the present study was to develop predictive models for the potential generation and emission of ammonia in the production of broiler chickens with different types of litter, different reuse cycles and under different climatic conditions. Samples of poultry litter from thirty commercial aviaries submitted to different air temperatures were analyzed. The experiment was conducted and analyzed in a completely randomized design, following a factorial scheme. Models were developed to predict the potential for generation and emission of ammonia, which can be applied in facilities with ambient conditions of air temperature between 25 and 40 °C and with wood shaving bed with up to four reuse cycles and coffee husks bed with up to six reuse cycles. The developed and validated models showed high accuracy indicating that they can be used to estimate the potential for ammonia generation and emission.

El objetivo de la presente fue modelar el comportamiento térmico de un secador solar típico para café tomando en consideración algunas configuraciones geométricas en la apertura de ventanas, en pos de mejorar las condiciones de secado natural al interior de la estructura. El modelo se simuló con datos experimentales en un secador solar típico en Colombia con Ansys CFX®. Los resultados mostraron que la geometría con una apertura del 25 % en la ventana para la salida del aire aumentó la temperatura sobre la capa de café hasta 4,2 °C con respecto a la temperatura ambiente, lo cual garantiza uniformidad en el secado, mientras la geometría típica con una apertura del 100 % aumentó la temperatura hasta 3,6 °C, no obstante, con ambas aperturas se aumentó la humedad relativa sobre la capa de café hasta 0,7 % con respecto a la humedad relativa ambiental. Con la apertura máxima de las ventanas disminuyó la humedad relativa del aire.

<p>En países con climas tropicales, como Brasil, las altas temperaturas asociadas con altas humedades relativas en el verano contribuyen como un factor de estrés en la producción animal. El calor excesivo dentro de una instalación avícola causa una reducción en el consumo de alimento y en la producción, y aumento en la mortalidad de las aves. Conociendo que el 75% de la carga de calor radiante dentro de una instalación viene desde el techo, es necesario estudiar alternativas que pueden minimizar esta radiación. El objetivo del presente trabajo fue analizar el ambiente térmico dentro de los modelos físicos de instalaciones de pollos de engorde construidos a escala reducida (1:10), donde el confort térmico se evaluó por el índice de humedad y de globo negro (BGHI) y la carga de calor radiante (RHL). Cinco modelos construidos fueron evaluados con diferentes materiales para techos. Basados en los resultados, se puede concluir que los techos construidos con tejas de cerámica (TB30), placas de fibra natural pintadas de blanco con en el lado externo (TFVP15) y placas de fabricadas con envases larga vida reciclado (TLV15), proporcionan los mejores ambientes térmicos.</p>