This page has only limited features, please log in for full access.
With an increasing number of naturally ventilated dairy barns (NVDBs), the emission of ammonia and greenhouse gases into the surrounding environment is expected to increase as well. It is very challenging to accurately determine the amount of gases released from a NVDB on-farm. Moreover, control options for the micro-climate to increase animal welfare are limited in an NVDB at present. Both issues are due to the complexity of the NVDB micro-environment, which is subject to temporal (such as wind direction and temperature) and spatial (such as openings and animals acting as airflow obstacles) fluctuations. The air exchange rate (AER) is one of the most valuable evaluation entities, since it is directly related to the gas emission rate and animal welfare. In this context, our study determined the general and local AERs of NVDBs of different shapes under diverse airflow conditions. Previous works identified main influencing parameters for the general AER and mathematically linked them together to predict the AER of the barn as a whole. The present research study is a continuation and extension of previous studies about the determination of AER. It provides new insights into the influence of convection flow regimes. In addition, it goes further in precision by determining the local AERs, depending on the position of the considered volume inside the barn. After running several computational fluid dynamics (CFD) simulations, we used the statistical tool of general linear modeling in order to identify quantitative relationships between the AER and the following five influencing parameters, the length/width ratio of the barn, the side opening configuration, the airflow temperature, magnitude and incoming direction. The work succeeded in taking the temperature into account as a further influencing parameter in the model and, thus, for the first time, in analysing the effect of the different types of flow convection in this context. The resulting equations predict the barn AER with an
E. Doumbia; David Janke; Qianying Yi; Alexander Prinz; Thomas Amon; Martin Kriegel; Sabrina Hempel. A Parametric Model for Local Air Exchange Rate of Naturally Ventilated Barns. Agronomy 2021, 11, 1585 .
AMA StyleE. Doumbia, David Janke, Qianying Yi, Alexander Prinz, Thomas Amon, Martin Kriegel, Sabrina Hempel. A Parametric Model for Local Air Exchange Rate of Naturally Ventilated Barns. Agronomy. 2021; 11 (8):1585.
Chicago/Turabian StyleE. Doumbia; David Janke; Qianying Yi; Alexander Prinz; Thomas Amon; Martin Kriegel; Sabrina Hempel. 2021. "A Parametric Model for Local Air Exchange Rate of Naturally Ventilated Barns." Agronomy 11, no. 8: 1585.
The tracer gas method is one of the common ways to evaluate the air exchange rate in a naturally ventilated barn. One crucial condition for the accuracy of the method is that both considered gases (pollutant and tracer) are perfectly mixed at the points where the measurements are done. In the present study, by means of computational fluids dynamics (CFD), the mixing ratio NH
E. Doumbia; David Janke; Qianying Yi; Guoqiang Zhang; Thomas Amon; Martin Kriegel; Sabrina Hempel. On Finding the Right Sampling Line Height through a Parametric Study of Gas Dispersion in a NVB. Applied Sciences 2021, 11, 4560 .
AMA StyleE. Doumbia, David Janke, Qianying Yi, Guoqiang Zhang, Thomas Amon, Martin Kriegel, Sabrina Hempel. On Finding the Right Sampling Line Height through a Parametric Study of Gas Dispersion in a NVB. Applied Sciences. 2021; 11 (10):4560.
Chicago/Turabian StyleE. Doumbia; David Janke; Qianying Yi; Guoqiang Zhang; Thomas Amon; Martin Kriegel; Sabrina Hempel. 2021. "On Finding the Right Sampling Line Height through a Parametric Study of Gas Dispersion in a NVB." Applied Sciences 11, no. 10: 4560.
Ammonia emissions from naturally ventilated livestock buildings (NVLBs) pose a serious environmental problem. However, the mechanisms that control these emissions are still not fully understood. One promising method for understanding these mechanisms is physical modelling in wind tunnels. This paper reviews studies that have used this method to investigate flow or pollutant dispersion within or from NVLBs. The review indicates the importance of wind tunnels for understanding the flow and pollutant dispersion processes within and from NVLBs. However, most studies have investigated the flow, while only few studies have focused on pollutant dispersion. Furthermore, only few studies have simulated all the essential parameters of the approaching boundary layer. Therefore, this paper discusses these shortcomings and provides tips and recommendations for further research in this respect.
Štěpán Nosek; Zbyněk Jaňour; David Janke; Qianying Yi; André Aarnink; Salvador Calvet; Mélynda Hassouna; Michala Jakubcová; Peter Demeyer; Guoqiang Zhang. Review of Wind Tunnel Modelling of Flow and Pollutant Dispersion within and from Naturally Ventilated Livestock Buildings. Applied Sciences 2021, 11, 3783 .
AMA StyleŠtěpán Nosek, Zbyněk Jaňour, David Janke, Qianying Yi, André Aarnink, Salvador Calvet, Mélynda Hassouna, Michala Jakubcová, Peter Demeyer, Guoqiang Zhang. Review of Wind Tunnel Modelling of Flow and Pollutant Dispersion within and from Naturally Ventilated Livestock Buildings. Applied Sciences. 2021; 11 (9):3783.
Chicago/Turabian StyleŠtěpán Nosek; Zbyněk Jaňour; David Janke; Qianying Yi; André Aarnink; Salvador Calvet; Mélynda Hassouna; Michala Jakubcová; Peter Demeyer; Guoqiang Zhang. 2021. "Review of Wind Tunnel Modelling of Flow and Pollutant Dispersion within and from Naturally Ventilated Livestock Buildings." Applied Sciences 11, no. 9: 3783.
Ammonia emissions damage the environment and have negative consequences for human and animal health. In the German livestock sector, most ammonia emissions come from naturally ventilated dairy barns. To reduce emissions, Germany has signed the EU Directive 2016/2284 to achieve a stepwise decrease in the ammonia emissions ceiling. The aim of this study was to investigate the seasonal mitigation effect of a urease inhibitor under practical conditions and provide information relating to two theoretical application scenarios in order to estimate an annual application scenario. The experimental design was conducted according to the requirements of the Verification of Environmental Technologies for Agricultural Production test protocol using the CO2 balance method to obtain the emissions. In a manual process, the inhibitor was applied to the floor surfaces of two dairy farms. The application took place once a day over three days during summer, winter and the transition period (spring/autumn). The ready-to-use liquid formulation of 1% inhibitor K dissolved in pyrrolidone was mixed with water resulting in 2.5 mg m−2 application rate of inhibitor and 50 ml m−2 water. The ammonia emissions on Farm A and Farm B were reduced by 40% and 53% in summer, 65% and 68% in winter and 64% and 54% in transition period, respectively. Thus, an annual reduction of 58% on Farm A and 57% on Farm B was observed. In a theoretical scenario where no inhibitor was applied during winter, up to 41% of the annual reduction was observed.
Anna B. Bobrowski; Diliara Willink; David Janke; Thomas Amon; Frauke Hagenkamp-Korth; Mario Hasler; Eberhard Hartung. Reduction of ammonia emissions by applying a urease inhibitor in naturally ventilated dairy barns. Biosystems Engineering 2021, 204, 104 -114.
AMA StyleAnna B. Bobrowski, Diliara Willink, David Janke, Thomas Amon, Frauke Hagenkamp-Korth, Mario Hasler, Eberhard Hartung. Reduction of ammonia emissions by applying a urease inhibitor in naturally ventilated dairy barns. Biosystems Engineering. 2021; 204 ():104-114.
Chicago/Turabian StyleAnna B. Bobrowski; Diliara Willink; David Janke; Thomas Amon; Frauke Hagenkamp-Korth; Mario Hasler; Eberhard Hartung. 2021. "Reduction of ammonia emissions by applying a urease inhibitor in naturally ventilated dairy barns." Biosystems Engineering 204, no. : 104-114.
The direct measurement of emissions from naturally ventilated dairy barns is challenging due to their large openings and the turbulent and unsteady airflow at the inlets and outlets. The aim of this study was to quantify the impacts of the number and positions of sensors on the estimation of volume flow rate and emissions. High resolution measurements of a naturally ventilated scaled building model in an atmospheric boundary layer wind tunnel were done. Tracer gas was released inside the model and measured at the outlet area, using a fast flame ionization detector (FFID). Additionally, the normal velocity on the area was measured using laser Doppler anemometry (LDA). In total, for a matrix of 65 × 4 sensor positions, the mean normal velocities and the mean concentrations were measured and used to calculate the volume flow rate and the emissions. This dataset was used as a reference to assess the accuracy while systematically reducing the number of sensors and varying the positions of them. The results showed systematic errors in the emission estimation up to + 97%, when measurements of concentration and velocity were done at one constant height. This error could be lowered under 5%, when the concentrations were measured as a vertical composite sample.
David Janke; Qianying Yi; Lars Thormann; Sabrina Hempel; Barbara Amon; Štěpán Nosek; Philippe Van Van Overbeke; Thomas Amon. Direct Measurements of the Volume Flow Rate and Emissions in a Large Naturally Ventilated Building. Sensors 2020, 20, 6223 .
AMA StyleDavid Janke, Qianying Yi, Lars Thormann, Sabrina Hempel, Barbara Amon, Štěpán Nosek, Philippe Van Van Overbeke, Thomas Amon. Direct Measurements of the Volume Flow Rate and Emissions in a Large Naturally Ventilated Building. Sensors. 2020; 20 (21):6223.
Chicago/Turabian StyleDavid Janke; Qianying Yi; Lars Thormann; Sabrina Hempel; Barbara Amon; Štěpán Nosek; Philippe Van Van Overbeke; Thomas Amon. 2020. "Direct Measurements of the Volume Flow Rate and Emissions in a Large Naturally Ventilated Building." Sensors 20, no. 21: 6223.
A reliable quantification of greenhouse gas emissions is a basis for the development of adequate mitigation measures. Protocols for emission measurements and data analysis approaches to extrapolate to accurate annual emission values are a substantial prerequisite in this context. We systematically analyzed the benefit of supervised machine learning methods to project methane emissions from a naturally ventilated cattle building with a concrete solid floor and manure scraper located in Northern Germany. We took into account approximately 40 weeks of hourly emission measurements and compared model predictions using eight regression approaches, 27 different sampling scenarios and four measures of model accuracy. Data normalization was applied based on median and quartile range. A correlation analysis was performed to evaluate the influence of individual features. This indicated only a very weak linear relation between the methane emission and features that are typically used to predict methane emission values of naturally ventilated barns. It further highlighted the added value of including day-time and squared ambient temperature as features. The error of the predicted emission values was in general below 10%. The results from Gaussian processes, ordinary multilinear regression and neural networks were least robust. More robust results were obtained with multilinear regression with regularization, support vector machines and particularly the ensemble methods gradient boosting and random forest. The latter had the added value to be rather insensitive against the normalization procedure. In the case of multilinear regression, also the removal of not significantly linearly related variables (i.e., keeping only the day-time component) led to robust modeling results. We concluded that measurement protocols with 7 days and six measurement periods can be considered sufficient to model methane emissions from the dairy barn with solid floor with manure scraper, particularly when periods are distributed over the year with a preference for transition periods. Features should be normalized according to median and quartile range and must be carefully selected depending on the modeling approach.
Sabrina Hempel; Julian Adolphs; Niels Landwehr; Dilya Willink; David Janke; Thomas Amon. Supervised Machine Learning to Assess Methane Emissions of a Dairy Building with Natural Ventilation. Applied Sciences 2020, 10, 6938 .
AMA StyleSabrina Hempel, Julian Adolphs, Niels Landwehr, Dilya Willink, David Janke, Thomas Amon. Supervised Machine Learning to Assess Methane Emissions of a Dairy Building with Natural Ventilation. Applied Sciences. 2020; 10 (19):6938.
Chicago/Turabian StyleSabrina Hempel; Julian Adolphs; Niels Landwehr; Dilya Willink; David Janke; Thomas Amon. 2020. "Supervised Machine Learning to Assess Methane Emissions of a Dairy Building with Natural Ventilation." Applied Sciences 10, no. 19: 6938.
Airflow inside naturally ventilated dairy (NVD) buildings is highly variable and difficult to understand due to the lack of precious measuring techniques with the existing methods. Computational fluid dynamics (CFD) was applied to investigate the effect of different seasonal opening combinations of an NVD building on airflow patterns and airflow rate inside the NVD building as an alternative to full scale and scale model experiments. ANSYS 2019R2 was used for creating model geometry, meshing, and simulation. Eight ventilation opening combinations and 10 different reference air velocities were used for the series of simulation. The data measured in a large boundary layer wind tunnel using a 1:100 scale model of the NVD building was used for CFD model validation. The results show that CFD using standard k-ε turbulence model was capable of simulating airflow in and outside of the NVD building. Airflow patterns were different for different opening scenarios at the same external wind speed, which may affect cow comfort and gaseous emissions. Guiding inlet air by controlling openings may ensure animal comfort and minimize emissions. Non-isothermal and transient simulations of NVD buildings should be carried out for better understanding of airflow patterns.
Chayan Kumer Saha; Qianying Yi; David Janke; Sabrina Hempel; Barbara Amon; Thomas Amon. Opening Size Effects on Airflow Pattern and Airflow Rate of a Naturally Ventilated Dairy Building—A CFD Study. Applied Sciences 2020, 10, 6054 .
AMA StyleChayan Kumer Saha, Qianying Yi, David Janke, Sabrina Hempel, Barbara Amon, Thomas Amon. Opening Size Effects on Airflow Pattern and Airflow Rate of a Naturally Ventilated Dairy Building—A CFD Study. Applied Sciences. 2020; 10 (17):6054.
Chicago/Turabian StyleChayan Kumer Saha; Qianying Yi; David Janke; Sabrina Hempel; Barbara Amon; Thomas Amon. 2020. "Opening Size Effects on Airflow Pattern and Airflow Rate of a Naturally Ventilated Dairy Building—A CFD Study." Applied Sciences 10, no. 17: 6054.
Emissions and ventilation rates (VRs) in naturally ventilated dairy barns (NVDBs) are usually measured using indirect methods, where the choice of inside and outside sampling locations (i.e. sampling strategy) is crucial. The goal of this study was to quantify the influence of the sampling strategy on the estimation of emissions and VRs. We equipped a NVDB in northern Germany with an extensive measuring setup capable of measuring emissions under all wind conditions. Ammonia (NH3) and carbon dioxide (CO2) concentrations were measured with two Fourier-transform infrared spectrometers. Hourly values for ventilation rates and emissions for ammonia over a period of nearly a year were derived using the CO2 balance method and five different sampling strategies for the acquisition of indoor and outdoor concentrations were applied. When comparing the strategy estimating the highest emission level to the strategy estimating the lowest, the differences in NH3 emissions in winter, transition, and summer season were +26%, +19% and +11%, respectively. For the ventilation rates, the differences were +80%, +94%, and 63% for the winter, transition and summer season, respectively. By accommodating inside/outside concentration measurements around the entire perimeter of the barn instead of a reduced part of the perimeter (aligned to a presumed main wind direction), the amount of available data substantially increased for around 210% for the same monitoring period.
David Janke; Dylia Willink; Christian Ammon; Sabrina Hempel; Sabine Schrade; Peter Demeyer; Eberhard Hartung; Barbara Amon; Nico Ogink; Thomas Amon. Calculation of ventilation rates and ammonia emissions: Comparison of sampling strategies for a naturally ventilated dairy barn. Biosystems Engineering 2020, 198, 15 -30.
AMA StyleDavid Janke, Dylia Willink, Christian Ammon, Sabrina Hempel, Sabine Schrade, Peter Demeyer, Eberhard Hartung, Barbara Amon, Nico Ogink, Thomas Amon. Calculation of ventilation rates and ammonia emissions: Comparison of sampling strategies for a naturally ventilated dairy barn. Biosystems Engineering. 2020; 198 ():15-30.
Chicago/Turabian StyleDavid Janke; Dylia Willink; Christian Ammon; Sabrina Hempel; Sabine Schrade; Peter Demeyer; Eberhard Hartung; Barbara Amon; Nico Ogink; Thomas Amon. 2020. "Calculation of ventilation rates and ammonia emissions: Comparison of sampling strategies for a naturally ventilated dairy barn." Biosystems Engineering 198, no. : 15-30.
The application of naturally ventilated pig buildings (NVPBs) with outdoor exercise yards is on the rise mainly due to animal welfare considerations, while the issue of emissions from the buildings to the surrounding environment is important. Since air pollutants are mainly transported by airflow, the knowledge on the airflow characteristics downwind the building is required. The objective of this research was to investigate airflow properties downwind of a NVPB with a roofed outdoor exercise yard for roof slopes of 5°, 15°, and 25°. Air velocities downwind a 1:50 scaled NVPB model were measured using a Laser Doppler Anemometer in a large boundary layer wind tunnel. A region with reduced mean air velocities was found along the downwind side of the building with a distance up to 0.5 m (i.e., 3.8 times building height), in which the emission concentration might be high. Additional air pollutant treatment technologies applied in this region might contribute to emission mitigation effectively. Furthermore, a wake zone with air recirculation was observed in this area. A smaller roof slope (i.e., 5° slope) resulted in a higher and shorter wake zone and thus a shorter air pollutant dispersion distance.
Qianying Yi; David Janke; Lars Thormann; Guoqiang Zhang; Barbara Amon; Sabrina Hempel; Štěpán Nosek; Eberhard Hartung; Thomas Amon. Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution. Applied Sciences 2020, 10, 4931 .
AMA StyleQianying Yi, David Janke, Lars Thormann, Guoqiang Zhang, Barbara Amon, Sabrina Hempel, Štěpán Nosek, Eberhard Hartung, Thomas Amon. Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution. Applied Sciences. 2020; 10 (14):4931.
Chicago/Turabian StyleQianying Yi; David Janke; Lars Thormann; Guoqiang Zhang; Barbara Amon; Sabrina Hempel; Štěpán Nosek; Eberhard Hartung; Thomas Amon. 2020. "Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution." Applied Sciences 10, no. 14: 4931.
The application of naturally ventilated pig buildings (NVPBs) with outdoor exercise yards is on the rise mainly due to animal welfare considerations, while the issue of emissions from the buildings to the surrounding environment is important. Since air pollutants are mainly transported by airflow, the knowledge on the airflow characteristics downwind the building is required. The objective of this research was to investigate airflow properties downwind of a NVPB with a roofed outdoor exercise yard for roof slopes of 5°, 15°, and 25°. Air velocities downwind a 1:50 scaled NVPB model were measured using a Laser Doppler Anemometer in a large boundary layer wind tunnel. A region with reduced mean air velocities was found along the downwind side of the building with a distance up to 0.5 m (i.e. 3.8 times building height), in which the emission concentration might be high. It was found that a smaller roof slope (i.e. 5° slope) resulted in a higher and shorter wake zone and thus a shorter air pollutant dispersion distance. It was concluded that a smaller roof slope could contribute to the dilution of air pollutants and a lower air pollutant concentration near the ground.
Qianying Yi; David Janke; Lars Thormann; Guoqiang Zhang; Barbara Amon; Sabrina Hempel; Štěpán Nosek; Eberhard Hartung; Thomas Amon. Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution. 2020, 1 .
AMA StyleQianying Yi, David Janke, Lars Thormann, Guoqiang Zhang, Barbara Amon, Sabrina Hempel, Štěpán Nosek, Eberhard Hartung, Thomas Amon. Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution. . 2020; ():1.
Chicago/Turabian StyleQianying Yi; David Janke; Lars Thormann; Guoqiang Zhang; Barbara Amon; Sabrina Hempel; Štěpán Nosek; Eberhard Hartung; Thomas Amon. 2020. "Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution." , no. : 1.
Two transient open source solvers, OpenFOAM and ParMooN, and the commercial solver Ansys Fluent are assessed with respect to the simulation of the turbulent air flow inside and around a dairy barn. For this purpose, data were obtained in an experimental campaign at a 1:100 scaled wind tunnel model. All solvers used different meshes, discretization schemes, and turbulence models. The experimental data and numerical results agree well for time-averaged stream-wise and vertical-wise velocities. In particular, the air exchange was predicted with high accuracy by both open source solvers with relative differences less than 4% and by the commercial solver with a relative difference of 9% compared to the experimental results. With respect to the turbulent quantities, good agreements at the second (downwind) half of the barn inside and especially outside the barn could be achieved, where all codes accurately predicted the flow separation and, in many cases, the root-mean-square velocities. Deviations between simulations and experimental results regarding turbulent quantities could be observed in the first part of the barn. These deviations can be attributed to the utilization of roughness elements between inlet and barn in the experiment that were not modeled in the numerical simulations. Both open source solvers proved to be promising tools for the accurate prediction of time-dependent phenomena in an agricultural context, e.g., like the transport of particulate matter or pathogen-laden aerosols in and around agricultural buildings.
David Janke; Alfonso Caiazzo; Naveed Ahmed; Najib Alia; Oswald Knoth; Baptiste Moreau; Ulrich Wilbrandt; Dilya Willink; Thomas Amon; Volker John. On the feasibility of using open source solvers for the simulation of a turbulent air flow in a dairy barn. Computers and Electronics in Agriculture 2020, 175, 105546 .
AMA StyleDavid Janke, Alfonso Caiazzo, Naveed Ahmed, Najib Alia, Oswald Knoth, Baptiste Moreau, Ulrich Wilbrandt, Dilya Willink, Thomas Amon, Volker John. On the feasibility of using open source solvers for the simulation of a turbulent air flow in a dairy barn. Computers and Electronics in Agriculture. 2020; 175 ():105546.
Chicago/Turabian StyleDavid Janke; Alfonso Caiazzo; Naveed Ahmed; Najib Alia; Oswald Knoth; Baptiste Moreau; Ulrich Wilbrandt; Dilya Willink; Thomas Amon; Volker John. 2020. "On the feasibility of using open source solvers for the simulation of a turbulent air flow in a dairy barn." Computers and Electronics in Agriculture 175, no. : 105546.
The mandate to limit global temperature rise calls for a reliable quantification of gaseous pollutant emissions as a basis for effective mitigation. Methane emissions from ruminant fermentation are of particular relevance in the context of greenhouse gas mitigation. The emission dynamics are so far insufficiently understood. We analyzed hourly methane emission data collected during contrasting seasons from two naturally ventilated dairy cattle buildings with concrete floor and performed a second order polynomial regression. We found a parabolic temperature dependence of the methane emissions irrespective of the measurement site and setup. The position of the parabola vertex varied when considering different hours of the day. The circadian rhythm of methane emissions was represented by the pattern of the fitted values of the constant term of the polynomial and could be well explained by feeding management and air flow conditions. We found barn specific emission minima at ambient temperatures around 10 °C to 15 °C. As this identified temperature optimum coincides with the welfare temperature of dairy cows, we concluded that temperature regulation of dairy cow buildings with concrete floor should be considered and further investigated as an emission mitigation measure. Our results further indicated that empirical modeling of methane emissions from the considered type of buildings with a second order polynomial for the independent variable air temperature can increase the accuracy of predicted long-term emission values for regions with pronounced seasonal temperature fluctuations.
Sabrina Hempel; Diliara Willink; David Janke; Christian Ammon; Barbara Amon; Thomas Amon. Methane Emission Characteristics of Naturally Ventilated Cattle Buildings. Sustainability 2020, 12, 4314 .
AMA StyleSabrina Hempel, Diliara Willink, David Janke, Christian Ammon, Barbara Amon, Thomas Amon. Methane Emission Characteristics of Naturally Ventilated Cattle Buildings. Sustainability. 2020; 12 (10):4314.
Chicago/Turabian StyleSabrina Hempel; Diliara Willink; David Janke; Christian Ammon; Barbara Amon; Thomas Amon. 2020. "Methane Emission Characteristics of Naturally Ventilated Cattle Buildings." Sustainability 12, no. 10: 4314.
Naturally ventilated livestock buildings (NVLB) represent one of the most significant sources of ammonia emissions. However, even the dispersion of passive gas in an NVLB is still not well understood. In this paper, we present a detailed investigation of passive pollutant dispersion in a model of a cattle barn using the wind tunnel experiment method. We simulated the pollution of the barn by a ground-level planar source. We used the time-resolved particle image velocimetry (TR-PIV) and the fast flame ionisation detector (FFID) to study the flow and dispersion processes at high spatial and temporal resolution. We employed the Proper Orthogonal Decomposition (POD) and Oscillating Patterns Decomposition (OPD) methods to detect the coherent structures of the flow. The results show that the type of atmospheric boundary layer (ABL) and sidewall opening height have a significant impact on the pollutant dispersion in the barn, while the presence of animals and doors openings are insignificant under conditions of winds perpendicular to the sidewall openings. We found that the dynamic coherent structures, developed by the Kelvin-Helmholtz instability, contribute to the pollutant transport in the barn. We demonstrate that in any of the studied cases the pollutant was not well mixed within the barn and that a significant underestimation (up to by a factor 3) of the barn ventilation might be obtained using, e.g. tracer gas method.
Štěpán Nosek; Zuzana Kluková; Michala Jakubcová; Qianying Yi; David Janke; Peter Demeyer; Zbyněk Jaňour. The impact of atmospheric boundary layer, opening configuration and presence of animals on the ventilation of a cattle barn. Journal of Wind Engineering and Industrial Aerodynamics 2020, 201, 104185 .
AMA StyleŠtěpán Nosek, Zuzana Kluková, Michala Jakubcová, Qianying Yi, David Janke, Peter Demeyer, Zbyněk Jaňour. The impact of atmospheric boundary layer, opening configuration and presence of animals on the ventilation of a cattle barn. Journal of Wind Engineering and Industrial Aerodynamics. 2020; 201 ():104185.
Chicago/Turabian StyleŠtěpán Nosek; Zuzana Kluková; Michala Jakubcová; Qianying Yi; David Janke; Peter Demeyer; Zbyněk Jaňour. 2020. "The impact of atmospheric boundary layer, opening configuration and presence of animals on the ventilation of a cattle barn." Journal of Wind Engineering and Industrial Aerodynamics 201, no. : 104185.
Environmental protection efforts can only be effective in the long term with a reliable quantification of pollutant gas emissions as a first step to mitigation. Measurement and analysis strategies must permit the accurate extrapolation of emission values. We systematically analyzed the added value of applying modern machine learning methods in the process of monitoring emissions from naturally ventilated livestock buildings to the atmosphere. We considered almost 40 weeks of hourly emission values from a naturally ventilated dairy cattle barn in Northern Germany. We compared model predictions using 27 different scenarios of temporal sampling, multiple measures of model accuracy, and eight different regression approaches. The error of the predicted emission values with the tested measurement protocols was, on average, well below 20%. The sensitivity of the prediction to the selected training dataset was worse for the ordinary multilinear regression. Gradient boosting and random forests provided the most accurate and robust emission value predictions, accompanied by the second-smallest model errors. Most of the highly ranked scenarios involved six measurement periods, while the scenario with the best overall performance was: One measurement period in summer and three in the transition periods, each lasting for 14 days.
Sabrina Hempel; Julian Adolphs; Niels Landwehr; David Janke; Thomas Amon. How the Selection of Training Data and Modeling Approach Affects the Estimation of Ammonia Emissions from a Naturally Ventilated Dairy Barn—Classical Statistics versus Machine Learning. Sustainability 2020, 12, 1030 .
AMA StyleSabrina Hempel, Julian Adolphs, Niels Landwehr, David Janke, Thomas Amon. How the Selection of Training Data and Modeling Approach Affects the Estimation of Ammonia Emissions from a Naturally Ventilated Dairy Barn—Classical Statistics versus Machine Learning. Sustainability. 2020; 12 (3):1030.
Chicago/Turabian StyleSabrina Hempel; Julian Adolphs; Niels Landwehr; David Janke; Thomas Amon. 2020. "How the Selection of Training Data and Modeling Approach Affects the Estimation of Ammonia Emissions from a Naturally Ventilated Dairy Barn—Classical Statistics versus Machine Learning." Sustainability 12, no. 3: 1030.