Keller Sullivan Oliveira Rocha

Three-Dimensional Modeling and Simulation of Heat and Mass Transfer Processes in Porous Media: An Application for Maize Stored in a Flat Bin

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.

A new computational method for hepatic fat microvesicles counting in histological study in rats.

Liver steatosis was once believed to be a benign condition, with rare progression to chronic liver disease. Thus, in both clinical and experimental practice, it is fundamental to have a reliable and objective method for its precise quantification. An image analysis algorithm was developed and validated for automatically and rapidly quantifying hepatic fat microvesicles. The image processing algorithms automatically segmented interstitial steatosis areas and analyzed the threshold region. Automatic quantifications did not significantly differ from manual evaluations of means of the same areas. Comparison of our image analysis quantifications with staging of histologic evaluations of liver steatosis presented significant correlations that are based on the distribution patterns and on the area quantity of steatosis, respectively. The use of algorithms for analysis and image processing is a sensitive, precise, objective and reproducible method of quantifying hepatic fat microvesicles, which complements semi-quantitative histologic evaluation systems.

3D-CFD modeling of a typical uninsulated and internal misting tunnel ventilated Brazilian poultry house

In order to control the thermal environment inside the poultry building and minimize heat stress during the warmest seasons and hottest hours of the day, nearly the entire modern poultry industry around the world (both tropical and temperate climates) is using negative pressure tunnel ventilation with evaporative cooling system, provided by internal misting and/or a cellulosic cooling pad. Computational Fluid Dynamics (CFD) modeling has been used in some studies to evaluate the thermal environment in insulated poultry houses located in temperate climates (Blanes et al. 2008; Norton et al. 2007; Norton et al. 2009). However, there is no information on the use of CFD in uninsulated poultry housing such as those encountered in tropical climates like that of Brazil. The aim of this study was to develop and use a CFD model to analyze the distribution of the air temperature and velocity inside a typical uninsulated commercial Brazilian poultry housing equipped with negative pressure ventilation and an evaporative cooling pad system. The distribution of air velocity and temperature inside the facility showed good statistical correlation with the experimental data. Therefore the CFD model can be used to predict real time thermal environment behavior.

Remote environmental monitoring and management of data systems.

As instrumentation and measurement system technology develop, the demand for faster and more reliable data transfer increases. At the same time, data collection in field research is becoming more expensive given the necessity of the researcher’s on-site presence. This requires that researchers invest significant amounts of time on the acquisition of data, especially when points of collection are geographically stratified. The utilization of communication networks in instrumentation systems enables remote analysis of data in real-time, allowing researchers to explore more diverse uses for the data. Such systems can be easily utilized by multiple users, regardless of their location. The objective of this project was to develop a system for remote management of data transmission over diverse communication interfaces. This goal was achieved by developing a protocol system that allows remote storage, access, and transmission of data. In this case, the data used was obtained from previously implemented projects. With a standardized method of data storage, collected data takes a consistent form. Databanks created facilitate the inclusion and recuperation of information in an unequivocal format, allowing researchers to integrate the information efficiently in their research projects. Project activities can be easily and reliably managed, making possible a more organized execution of field studies and eliminating problematic manual registers.

Modeling and Simulation of the Transient Response of Temperature and Relative Humidity Sensors with and without Protective Housing

Based on the necessity for enclosure protection of temperature and relative humidity sensors installed in a hostile environment, a wind tunnel was used to quantify the time that the sensors take to reach equilibrium in the environmental conditions to which they are exposed. Two treatments were used: (1) sensors with polyvinyl chloride (PVC) enclosure protection, and (2) sensors with no enclosure protection. The primary objective of this study was to develop and validate a 3-D computational fluid dynamics (CFD) model for analyzing the temperature and relative humidity distribution in a wind tunnel using sensors with PVC enclosure protection and sensors with no enclosure protection. A CFD simulation model was developed to describe the temperature distribution and the physics of mass transfer related to the airflow relative humidity. The first results demonstrate the applicability of the simulation. For verification, a sensor device was successfully assembled and tested in an environment that was optimized to ensure fast change conditions. The quantification setup presented in this paper is thus considered to be adequate for testing different materials and morphologies for enclosure protection. The results show that the boundary layer flow regime has a significant impact on the heat flux distribution. The results indicate that the CFD technique is a powerful tool which provides a detailed description of the flow and temperature fields as well as the time that the relative humidity takes to reach equilibrium with the environment in which the sensors are inserted.

ASPERSÃO DE ÁGUA DE CHUVA ARMAZENADA SOBRE A COBERTURA DE AVIÁRIOS COM TELHAS DE AÇO NA REGIÃO CENTRO OESTE DO BRASIL

Objetivou-se com este trabalho estudar os principais efeitos da aspersao de agua de chuva armazenada sobre a cobertura de telhas de aco de instalacoes comerciais para producao de frangos de corte, na regiao centro-oeste do Brasil. Foram avaliados variaveis climaticas, temperatura da superficie inferior das telhas, indices zootecnicos e indices de conforto termico. Adicionalmente, foram avaliados o tempo de funcionamento, o consumo de agua e o consumo de energia pelo sistema de resfriamento. O delineamento experimental foi inteiramente casualizado com dois tratamentos e tres repeticoes: Tratamento um - tres aviarios equipados com sistema de resfriamento interno, modo tunel com pressao negativa, e aspersao de agua de chuva armazenada sobre a cobertura de telhas de aco (CA); Tratamento dois - tres aviarios identicos aos do tratamento 1 embora, sem aspersao de agua sobre a cobertura (SA). O tratamento CA, em media, proporcionou a reducao de 19,5°C na temperatura media da superficie interna das telhas no horario mais critico do dia as 15:00h e reduziu a temperatura media do ambiente ao nivel das aves em 1,9 °C. Ademais, os indices de conforto termico no tratamento CA apresentaram valores inferiores durante todo periodo experimental, houve reducao no tempo de funcionamento do segundo grupo de exaustor em 4,8 %, no terceiro grupo em 7,5 % e na bomba de nebulizacao interna em 9,6 %, reduzindo assim o consumo de energia eletrica, reducao na mortalidade, melhoria na conversao alimentar e aumento no ganho de massa corporal media das aves ao abate

Mapping thermal environment inside broiler barns for the diagnosis of cold stress at bird initial growing stage.

Average temperature for the whole air volume within a broiler house may not be representative and in some cases it could mask thermal discomfort situations for broilers, especially in their growing period. At this stage, chicks are susceptible to cold stress, which might lead to developmental disorders that will compromise their overall performance. This study was conducted with the aim of mapping the dry-bulb temperature within the bird influence zone for a negative pressure barn (NPB) and a naturally ventilated barn (NVB), both for broilers, during the first three weeks of age, the investigated barns have an architecture that is usually adopted in warm climate conditions, such as Brazil, i.e. non-insulated and occasionally open by lowering the curtains. The mapping results suggested that the insulation capacity of the NVB was poorer as compared to the NPB, while average temperature during the night period was below thermoneutrality for both barns during most of the time, suggesting that both heating systems were undersized. Temperature maps also suggested that heated air was poorly mixed in the NVB during the first two weeks of age being that during the night period the cold air temperature (also in both cases) exposed the chicks to cold stress situations.

CFD modeling of air quality inside naturally ventilated broiler barns as a function of barn spatial arrangement

One of the most effective ways to improve air quality inside high density poultry barns comes still during the conception of the farm project, such as adopting a minimum distance between naturally ventilated barns that will prevent, at least partially, the exhaust air from one barn to enter the next one downwind. The aim of this study was to use CFD (Computational Fluid Dynamics) to model ammonia (NH3) concentrations inside naturally ventilated broiler houses and to assess the influence of the surrounding of four poultry houses G1, G2, G3 and G4, all identical with the dimensions 13.5m W x 100m L x 3.5m H, under three typical house spatial arrangements. The different topologies were modeled: In arrangement A1, distances between barns will be as in A2 but the front wall of G2 will be translated 25 m to the axial direction as compared to the G1, and B3 25 m to the same axial direction as compared to G2.. For the second arrangement (A2), four poultry barns are positioned side by side with a distance of 35m (side-wall to side wall). For the one another arrangement (A3), the barn G2 will be located 35m from the G1 (downwind) but G3 will be positioned 100m downwind G2. Climatic conditions were being those of a typical summer day in a tropical region like Brazil. Ammonia concentration data was validated, and showed good agreement with experimental data, and the simulations indicated that the arrangement A1 reduced the cumulative effect of the upwind barns, presenting the best results.

Use of CFD modeling for determination of ammonia emission in non-insulated poultry houses with natural ventilation

The understanding of distribution of gases such as ammonia (NH3) in agricultural installations is of growing importance due to its effect on health and productivity of animals and workers. There are methodologies available for determination of NH3 emissions in poultry houses by continuous monitoring like the portable monitoring unit (PMU) and mobile air emissions monitoring unit (MAEMU) methods, tracer gas ratio method and Model-based approach of mass balance. However all methods require long experimentation periods. Computational Fluid Dynamics (CFD) is a powerful and efficient tool which allows for prediction of this distribution of gases in real time, which allows for a reduction of the number of experiments. Based on these facts, the aim of this study was to use CFD to develop and validate a model to determine NH3 emissions in a non-insulated broiler house installation with natural ventilation, typical to subtropical and tropical countries. It was found that the proposed model showed a good statistical correlation with the experimental data that were based in the methodologies used by Wheeler et al. (2006) and Osorio (2011). Therefore this CFD model could be used to predict behavior of NH3 emissions in real time generated by poultry facilities.

Evaluation of Different Minimum Ventilation Systems on Air Quality and Performance of Broilers in the Period of Fifteen to Twenty-One Days of Housing

The objective of this work was to evaluate the efficiency of different minimal ventilation systems (controlled by timing devices) including positive pressure ventilation (SVMP), negative pressure ventilation (SVMN) and natural ventilation (SVMNat), associated to the thermal comfort environment, air quality and the influence of these factors on the productive performance of broiler chicken during the finishing stage of heating. The study was developed in a commercial poultry house integrated during the winter in the Minas Gerais State. Three points along the length of the building, as well as two points along the height of the building for verification of different environmental variables, air temperature, black globe temperature, relative humidity and air velocity at the level of bird and worker respiration. Ammonia, carbon monoxide and oxygen concentrations were verified at the times of 3, 9 15 and 21 h. No statistical difference (P<0.05) was observed for the variable bulb globe temperature index (ITGU). Average ITGU were below comfort levels for the birds, exposing them to cold stress in the majority of the time for the three minimal ventilation systems, indicating probable deficiencies in the heating systems and/or the insulation system for hatchlings in their initial growth phase. Average pollutant gas measurements did not surpass tolerable levels for the three minimal ventilation systems evaluated at the level of the broilers and workers. However, minimal ventilation systems were adequately dimensioned in terms of minimal air renewal, presenting no negative influences in relation to ventilation rates applied for the systems SVMN and SVMP.