If the relative humidity and temperature of the air inside a granular mass of stored grain exceeds a certain threshold value, microorganism activity is likely to increase. Lower relative humidity and temperature, when uniformly distributed inside the grain mass, prevent moisture migration and an increase in microorganism activity. To cool down or maintain the temperature of the grain mass below a threshold value, forced ventilation with an appropriate airflow can be used to remove excess moisture or heat generated by grain or microorganism respiration. The objective of this work was to solve the equations that describe the conservation of heat, mass, and momentum in order to predict heat and mass transfer processes in the environment inside a grain mass of maize, stored in a flat bin. Three-dimensional computational fluid dynamics was used to solve the equations. The analysis of heat and mass transfer was performed considering the geometry of a two-ton-capacity bin prototype using a hexahedral mesh for the finite volume analysis. The numerical grid was defined to discretize the physical flow domain of interest to calculate velocity, temperature, and moisture distribution in the bulk of stored grain. The predicted results were compared with experimental data, and the agreement between them was very good.

This study was conducted with the aim of monitoring NH3 emissions from a mechanically and a naturally ventilated broiler house (MVB and NVB, respectively) and calculate their ammonia emission factors (fNH3). Bird stocking density was 13.5 and 11.1 birds m-2 for the MVB and NVB, respectively. The marketing age was 43 days and bedding consisted of dried coffee husks in its first time of use. Ventilation rates were calculated with the metabolic carbon dioxide mass balance method. Values of fNH3 were 0.32 ± 0.10 and 0.27 ± 0.07 g bird-1 d-1 for the MVB and NVB, respectively, and are in agreement to what was presented in other studies performed under similar conditions. The fNH3 estimated on yearly basis was 58 g bird-place-1 year-1. It was concluded that the different types of ventilation system between the studied broiler barns did not significantly affect emissions in the modeling process. The results obtained help providing reliable methodology for the determination of a solid database on NH3 emission factors for tropical conditions that can be used for future inventories, when performed in a sufficient number of barns that is representative for the Brazilian scenario.

The objective of this research was to evaluate the internal thermal environment of two broiler barns featuring different ventilation systems representative of Brazilian and South American poultry production industry: (a) a negative-pressure tunnel and (b) a positive-pressure lateral ventilation system. Environmental parameters such as dry bulb temperature, relative humidity and temperature-humidity index were assessed; temperature maps for day and night average conditions were determined for the first three weeks of life. Better uniformity of the thermal environment and comfort conditions inside the negative-pressure tunnel were found.

The aim of this study was to use computational fluids dynamics (CFD) to evaluate hygiene and comfort conditions in function of temperature level and ammonia (NH₃) concentration during the night in commercial poultry houses used in Brazil and countries with tropical and subtropical climates. Four models with different curtain heights and different air inlet and outlet positions were used, adopting the open building typology without thermal insulation. The validated CFD model did not present statistical differences from the experimental data, making it possible to use this model to predict the behavior in the four proposed cases. This model can be used to improve the internal conditions of the poultry facilities during the night and could be an important tool to reduce energy consumption and generate better conditions for animal production of chicks over 21 days old.

En las regiones de climas tropicales y subtropicales cálidos, los altos valores de temperatura del aire, especialmente en épocas secas, pueden afectar negativamente el confort térmico dentro de los locales utilizados para la producción pecuaria y agrícola, dando lugar a una reducción significativa en su producción. Con el fin de promover la disminución de la temperatura en de las instalaciones y mejorar el ambiente interno de estas, se han utilizado los sistemas de resfriamiento evaporativo del aire que se introduce en el ambiente, abriéndose paso a través de diferentes placas porosas humedecidas. Sin embargo, dificultades en la experimentación práctica a limitado drásticamente informaciones relativas a nuevos materiales porosos posibles de ser empleados en sustitución al material convencional (Material celulósico) patentado, de elevado costo y de baja durabilidad. Debido a lo anterior, este estudio tuvo como objetivo validar un modelo computacional en dinámica de fluidos computacionales (CFD) para predecir la eficiencia del resfriamiento (h) en placas porosas de arcilla expandidas humedecidas. Los resultados numéricos obtenidos por el modelo propuesto mostraron una buena correlación con los datos experimentales (81%), lo que indica su aptitud para predecir el comportamiento de este tipo de sistemas, y de otros materiales porosos.