Evaluation of a heating system in poultry houses using a cfd model / evaluación de un sistema de calefacción en galpones avicolas usando un modelo en cfd

Abstract.. The objective of this study was to adapt and validate a computer model using the Computational Fluid Dinamics (CFD), in the prediction of temperature and air speed in a duct distribution system coupled to a heating furnace that is used in typical poultry houses in tropical and subtropical countries. The validation of the model with experimental data was satisfactory, presentingnormalized mean square error NMSE values of 0.25 and 0.02 for air temperature and air speed, respectively. The results evidenced that the proposed model is adequate for predicting the air speed and temperature for this type of system, and could be used to improve the efficiency of the distribution of heat inside and around air ducts using different air speeds, types of materials and dimensions. / Resumen. El objetivo de este estudio fue adaptar y validar un modelo computacional haciendo uso de la dinámica de fluidos computacional (CFD) para predecir la temperatura y la velocidad del aire en un sistema de distribución de ductos acoplado a un sitema de calefacción que es utilizado en las instalaciones avícola en los países tropicales y subtropicales. La validación del modelo con los datos experimentales fue satisfactoria, presentando valores medios normalizados del error cuadrado NMSE de 0,25 y 0,02 para la temperatura y velocidad del aire respectivamente. Los resultados muestran que el modelo propuesto es adecuado para predecir la velocidad del aire y la temperatura alrededor de este tipo de sistema, y podría ser utilizado para mejorar la eficiencia la distribución de calor en el interior y alrededor de los conductos, usando diferentes velocidades, tipos de materiales y dimensiones

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Evaluation of means to measure emissions and air flows Through naturally ventilated livestock buildings

This thesis was prepared as an attempt to cover a number of questions and concerns regarding the current available means to measure emissions and air flows from naturally ventilated (NV) livestock buildings. Five were the main objectives that led to the preparation of this thesis: (1) to assess the operation performance of a low cost carbon dioxide (CO2) measuring device and to compare it to two other standard methods; (2) to evaluate the distribution of mixing ratios of the pollutant ammonia (NH3) and the tracer gases sulfur-hexafluoride (SF6) and CO2 in a NV dairy cow barn; (3) to develop a CFD model of a NV dairy cow barn implemented with the CIGR CO2 production model; (4) to develop and test a protocol for measuring NH3 emissions from a Brazilian NV broiler house; and (5) to calculate NH3 emission factors from a Brazilian NV and a mechanically ventilated (MV) broiler barns. Five papers were prepared to answer the five objectives of this thesis, which include a variety of factors and implications related to a NV dairy cow barn in the Netherlands and a NV broiler barn in Brazil. The first paper dealt with the comparison between two CO2 concentration measuring devices that are commonly used for emission studies in MV barns with one low cost sensor that is new to research purposes and might be more suitable for NV livestock buildings. In the second paper, we compared mixing ratios calculated with NH3 and two different tracers, the CO2 which is naturally produced in livestock houses and the artificially injected SF6 with the aim of identifying the region within the barn ventilated airspace where mixing ratios are approximately constant, from which representative estimates of emission rates through the tracer gas method can be made. In paper number three, a Computational Fluid Dynamics (CFD) model of a NV dairy cow barn was developed and implemented with the CIGR CO2 production equations in order to reveal the flow patterns of air and CO2 within the ventilated airspace. The model was validated with CO2 concentration data actually measured at multiple points within the barn. The fourth paper was about finding a more adequate algorithm for determining flow rates across a NV broiler barn in Brazil. The tested sampling strategies combined two different sampling schemes for gaseous concentrations and two different strategies to xi 13 predict CO2 production from the birds. The fifth and last paper was a follow up of paper number four, and dealt with calculation of actual NH3 emission factors ( NH3 f ) of a NV and a MV broiler barns in Brazil. The method used to estimate the emission factors in both barns was based on a tracer gas, using the CO2 naturally produced by the birds as the tracer. The calculated NH3 f were then compared to those found in the literature for Brazilian conditions and those found in other parts of the world. Overall, this thesis proves that despite the complications related to monitoring air and gaseous pollutant flows through NV buildings, emission factors can be obtained which are comparable to those of MV buildings. In general, the number of points in which gaseous concentrations are being monitored within the barn ventilated airspace with properly calibrated devices is more important than using highly accurate and expensive measurement methods. When the tracer gas method is to be used, focus should be given to accurate determination of the tracer injection rate or rate of production of CO2. It is important that the mixing ratio between pollutant and tracer gases be determined in multiple points outside the animal occupied zone, but above it.Esta tese foi preparada como uma tentativa de abordar uma série de questões importantes sobre os atuais meios disponíveis para medir emissões gasosas e os fluxos de ar em alojamentos animais com ventilação natural (VN). Cinco foram os principais objetivos que levaram à elaboração desta tese: (1) avaliar o desempenho operacional de um dispositivo de baixo custo para monitoramento de concentrações de dióxido de carbono (CO2) e compará-lo com dois outros métodos padrões; (2) avaliar o perfil de distribuição das razões de mistura entre o poluente amônia (NH3) e os gases marcadores hexafluoreto de enxofre (SF6) e CO2 em um galpão para vacas leiteiras com VN; (3) desenvolver um modelo CFD de um galpão de vaca leiteira com VN implementado com o modelo de produção de CO2 do CIGR; (4) desenvolver e testar um protocolo para medição das emissões de NH3 de um galpão brasileiro de frangos de corte com VN, e (5) calcular fatores de emissão de NH3 de dois galpões brasileiros com VN e ventilação mecânica (VM) para frangos de corte. Cinco artigos foram preparados para responder aos cinco objetivos desta tese, os quais incluem uma variedade de fatores e implicações relacionados a um galpão de vaca leiteiras com VN na Holanda e um galpão de frangos de corte com VN no Brasil. O primeiro trabalho versou sobre a comparação de dois métodos de monitoramento de concentrações de CO2 que são comumente usados para estudos de emissões em alojamentos animais com ventilação mecânica (VM) com um sensor de CO2 de baixo custo, e que é novo para fins de pesquisa, podendo ser mais adequado para uso galpões com VN. No segundo artigo, razões de mistura foram calculadas entre o gás NH3 e um dos dois gases marcadores distintos, o CO2 naturalmente liberado pelos animais e esterco, e o SF6 que foi artificialmente injetado no galpão. O objetivo maior deste artigo foi identificar a região dentro do galpão onde as razões de mistura possuem valores estimados aproximadamente constantes, de modo que taxas de emissão representativas para o galpão possam ser estimadas por meio do método do gás marcador. No artigo número três, um modelo em “Computational Fluid Dynamics” (CFD) de um galpão para vacas leiteiras com VN foi desenvolvido e ix 11 implementado com as equações de produção CO2 publicadas pelo CIGR, a fim de revelar os padrões de fluxo de ar e CO2 no espaço interno ventilado. O modelo foi validado com dados de concentração de CO2 medidos experimentalmente em vários pontos dentro do galpão. O quarto artigo versou sobre a determinação do algoritmo mais adequado para estimar as taxas de fluxo de ar e gases através de um galpão de frangos de corte com VN, localizado no Brasil. As estratégias de amostragem testadas consistiram de combinações de dois esquemas diferentes de monitoramento das concentrações gasosas e de duas estratégias de predição da produção de CO2 das aves. O quinto e último trabalho foi uma continuação do quarto artigo, e tratou do cálculo dos fatores de emissões de NH3 ( NH3 f ) de galpões com VN e VM para frangos de corte no Brasil. O método utilizado para calcular os fatores de emissão em ambos os galpões foi o do gás marcador, utilizando-se CO2 naturalmente produzido pelas aves. Os NH3 f calculados foram comparáveis com aqueles encontrados na literatura para as condições do Brasil e em outras partes do mundo. No geral, esta tese demonstra que, apesar das complicações relacionadas ao monitoramento dos fluxos de ar poluentes gasosos através de galpões animais com VN, os fatores de emissão obtidos podem ser comparáveis àqueles relativos a galpões animais com VM. Em síntese, o número de pontos no galpão em que as concentrações de gases serão monitoradas é mais relevante do que a utilização de métodos de medição de alta precisão e dispendiosos. Quando o método de gás marcador é utilizado, atenção deverá ser dada a determinação precisa da taxa de injeção do gás marcador ou a taxa de produção de CO2. É importante também que a razão de mistura entre os gases poluente e marcador seja determinada em vários pontos fora da zona ocupada pelos animais, porém acima dela

Ammonia emissions, feeding and defecation dynamics of W36 pullets and laying hens as affected by stocking density and manure accumulation time

A great deal of effort has been given through intensive research toward studying the sources of gaseous emissions from animal feeding operations (AFOs) and their influencing factors. Ammonia (NH3) is the most predominant noxious gas released from poultry production facilities and it is mainly affected by diet composition, manure temperature, moisture content and stacking configuration and manure surface area exposed to ambient air. However, current literature lacks information on bird age effects on NH3 emissions, even though changes in diet composition with bird age are expected to affect the emissions. Also, some producers have been using different bird stocking densities (SD) as an attempt to improve bird welfare. Nevertheless the effects of different bird SD regimens on NH3 emissions remain unknown. Moreover, it has been shown that different housing styles can have significant impacts on the magnitude of NH3 emissions from laying-hen facilities in that the high rise (HR) systems (typical of US egg production) emit 61 to 71 % more ammonia than the manure-belt (MB) systems (gaining more popularity in the US). The impact of manure accumulation time on the belts in MB systems on NH3 emissions needs to be quantified. Hence, a research study was conducted in a laboratory setting that resembled a commercial MB system for laying hens. The results of the study are presented in this thesis. Chapter 2 describes the effect of different SD regimens (155 to 619 cm2 bird-1 or 24 to 96 in2 bird-1) and manure accumulation time (MAT, 1 to 6 d) of pullets (hens < 18 weeks of age) and laying hens on NH3emissions. Results showed that daily NH3 emission rate (ER) for pullets and laying hens increased exponentially with bird age and MAT, while SD effect on NH3 ER was more pronounced for MAT ≥ 3d (P<0.0001). In general, higher SD led to higher ER. Specifically, for the laying hens, NH3 emissions from the 3rd to 6th d MAT ranged from 41 to 251 mg/hen-d for the high density (HD) and from 29 to 160 mg/hen-d for the low density (LD). This outcome supports the current egg industry practice of removing manure at 1- to 3-d MAT for the MB house systems. Chapter 3 assesses the dynamics of feeding, defecation and NH3 emissions of pullets and laying hens under different SDs (as used in the trials described in Chapter 2), MAT (1 to 6 d) during light and dark periods of the day. Results indicate that SD did not adversely affect feed disappearance or fresh manure production (P = 0.17 – 0.81) at any of the tested ages. For each gram of feed use, the fresh manure produced varied from 0.58 to 1.15 g bird-1 (P < 0.0001) varying according to bird age. The light and dark partitioning of feed disappearance was 92% to 8%, respectively, while the partitioning for fresh manure production was 80% to 20%. Results also revealed that 37% of the total daily NH3 emission occurred during the dark period vs. 63% during the light hours

Ammonia emission and performance of laying hens as affected by different dosages of Yucca schidigera in the diet

A laboratory-scale study was conducted to determine the effect of feeding laying hens astandard commercial diet supplemented with different dosages of Yucca schidigera powder onNh3 emission rate and production performance. a total of 72 W36 laying hens at 25 wk of agewere used during the 12-wk study. the birds were equally divided into 4 groups and randomlyallocated among 4 diets containing, respectively, 0, 50, 100, and 200 ppm (by weight) yuccapowder. the hens were reared in an environment of 24 ± 1°C and a concomitant Rh of 45 to65%. Measurement of Nh3 emission rate was done with a Gaseous emission Vessels System.the Y. schidigera powder in the laying-hen diet at a dosage of 50, 100, or 200 ppm did not affectthe production performance of laying hens when compared with the 0-ppm dosage. the100-ppm dosage significantly (P < 0.05) reduced Nh3 emission by 44 and 28%, respectively,for the first and second day of manure storage when compared with the other dosages. On thethird day, Nh3 reduction was 14% but was not significantly different from the other treatments.adding 50 or 200 ppm of yucca in the diet did not reduce Nh3 emission. hence, adding 100ppm of yucca in the laying-hen diet coupled with frequent manure removal (once every 1 to 2d) would be conducive to reducing Nh3 generation and emission in laying-hen barns