Research

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14 pages, 2522 KiB

Open AccessFeature PaperArticle

Verification Analysis of Volume Flow Measured by a Direct Method and by Two Indirect CO₂ Balance Methods

by David Janke, Diliara Willink, Christian Ammon, El-Hadj Moustapha Doumbia, Anke Römer, Barbara Amon, Thomas Amon and Sabrina Hempel

Appl. Sci. 2022, 12(10), 5203; https://0-doi-org.brum.beds.ac.uk/10.3390/app12105203 - 20 May 2022

Cited by 2 | Viewed by 1465

Abstract

Ammonia and greenhouse gases have a negative impact on the environment. The most important agricultural sources of ammonia are dairy cattle housing systems, which are mainly naturally ventilated. Estimating emissions for naturally ventilated barns (NVB) is challenging due to the large number of [...] Read more.

Ammonia and greenhouse gases have a negative impact on the environment. The most important agricultural sources of ammonia are dairy cattle housing systems, which are mainly naturally ventilated. Estimating emissions for naturally ventilated barns (NVB) is challenging due to the large number of influencing factors. Most notably, the direct coupling of the inside flow regime with ambient and turbulent weather conditions causes difficulties in measuring ventilation rates, gas concentrations and emissions; thus, different methods are available. In this study, we compared the outputs of total volume flow obtained by two indirect methods (CO

_{2}

mass balance) to the direct method. The latter we assume in this study as the reference method since it is a fundamental approach that estimates airflow on the inlet. In the context of mass balancing, we compared wind related (sampling method 1) and non-wind related (sampling method 2) approaches for measuring CO

_{2}

concentrations. The total volume flow calculations were based on hourly measurements of CO

_{2}

concentrations obtained by Fourier transform infrared (FTIR) spectrometer. Data were collected over a period of six months. The values of the total volume flow were filtered for prevailing southern winds (90

^{\circ}

angle). The wind related method (sampling method 1) in stable cross-inflow conditions produces more accurate and realistic values in terms of the general representation of the values in comparison with direct method and can be considered further for measurements of volume flow in the NVBs. Full article

(This article belongs to the Special Issue Novel Approaches for Assessment and Control of Gaseous Emission Levels at Animal Production Facilities)

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21 pages, 3072 KiB

Open AccessArticle

Supervised Machine Learning to Assess Methane Emissions of a Dairy Building with Natural Ventilation

by Sabrina Hempel, Julian Adolphs, Niels Landwehr, Dilya Willink, David Janke and Thomas Amon

Appl. Sci. 2020, 10(19), 6938; https://0-doi-org.brum.beds.ac.uk/10.3390/app10196938 - 03 Oct 2020

Cited by 13 | Viewed by 2841

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Novel Approaches for Assessment and Control of Gaseous Emission Levels at Animal Production Facilities)

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12 pages, 1619 KiB

Open AccessArticle

Concentrations and Emissions of Ammonia from Different Laying Hen Production Systems of Conventional Cage, Aviary and Natural Mating Colony Cage in North China Plain

by Yu Liu, Guoqiang Zhang, Li Rong, Zongyang Li, Shaojie Wang and Chaoyuan Wang

Appl. Sci. 2020, 10(19), 6820; https://0-doi-org.brum.beds.ac.uk/10.3390/app10196820 - 29 Sep 2020

Cited by 2 | Viewed by 1759

Abstract

Ammonia (NH₃) concentrations in summer were continuously monitored from three typical laying hen houses of CC (conventional cage), AV (aviary), and NM (natural mating colony cage) with manure belt systems in North China Plain to quantify their emission levels, to characterize [...] Read more.

Ammonia (NH₃) concentrations in summer were continuously monitored from three typical laying hen houses of CC (conventional cage), AV (aviary), and NM (natural mating colony cage) with manure belt systems in North China Plain to quantify their emission levels, to characterize the diurnal variations, and to investigate the impact of environmental factors. Diurnal profiles were acquired by hourly measurements, and the effect of environmental factors on NH₃ emissions was presented by correlation analysis. The results showed that house-level NH₃ emissions in summer were the highest in the NM at 27.16 ± 13.12 mg/h·hen, followed by the AV at 4.08 ± 3.23 mg/h·hen and the CC at 3.43 ± 1.46 mg/h·hen within a complete manure removal cycle, which were significantly affected by manure accumulation inside the houses. After manure removal, NH₃ concentrations were reduced by 64.29%, 28.57%, and 35.71% in CC, AV, and NM, and consequently their emissions were lowered by 67.12%, 71.36%, and 55.69%, respectively. It was suggested that the manure should not be stored on the belt for more than 4 days in NM. A positive impact of indoor and outdoor temperature and ventilation rate on NH₃ emissions from AV and NM were found, while indoor and outdoor relative humidity had a negative effect. However, the above five factors did not significantly affect the emissions from CC. Full article

(This article belongs to the Special Issue Novel Approaches for Assessment and Control of Gaseous Emission Levels at Animal Production Facilities)

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17 pages, 5320 KiB

Open AccessArticle

Opening Size Effects on Airflow Pattern and Airflow Rate of a Naturally Ventilated Dairy Building—A CFD Study

by Chayan Kumer Saha, Qianying Yi, David Janke, Sabrina Hempel, Barbara Amon and Thomas Amon

Appl. Sci. 2020, 10(17), 6054; https://0-doi-org.brum.beds.ac.uk/10.3390/app10176054 - 01 Sep 2020

Cited by 10 | Viewed by 3372

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Novel Approaches for Assessment and Control of Gaseous Emission Levels at Animal Production Facilities)

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13 pages, 464 KiB

Open AccessArticle

Validation of Five Gas Analysers for Application in Ammonia Emission Measurements at Livestock Houses According to the VERA Test Protocol

by Shaojie Zhuang, Eva Brusselman, Bart Sonck and Peter Demeyer

Appl. Sci. 2020, 10(15), 5034; https://0-doi-org.brum.beds.ac.uk/10.3390/app10155034 - 22 Jul 2020

Cited by 9 | Viewed by 2799

Abstract

Ammonia emissions are an important issue in livestock production. Many mitigation measures have been proposed in order to reduce the environmental impact of livestock farms, and reliable field measurements are required to evaluate the amount of released or reduced ammonia while applying these [...] Read more.

Ammonia emissions are an important issue in livestock production. Many mitigation measures have been proposed in order to reduce the environmental impact of livestock farms, and reliable field measurements are required to evaluate the amount of released or reduced ammonia while applying these measures. Following the guideline of the Verification of Environmental Technologies for Agricultural Production test protocol, five commercially available gas analysers, i.e., INNOVA 1314, Picarro G2103, Rosemount CT5100, Gasmet CX4000, and Axetris LGD F200-A, were validated as alternative methods to the wet-chemistry method (reference method) for measuring ammonia in livestock houses. High correlations (

r > 0.99

) were found between the analysers and the reference method. The measurement errors of the tested analysers were below 2 ppm_v or 10%. Equivalence to the wet-chemistry method was demonstrated for the INNOVA and Rosemount analysers without a recalibration and for the Picarro and Axetris analysers with a recalibration. The Gasmet analyser was seemingly subjected to an interference from carbon-dioxide and, after compensating for the cross-sensitivity, the equivalence to the wet-chemistry method could also be demonstrated. Calibration curves that were based on a certified gas cylinder were inconsistent with that based on wet-chemistry measurements, which suggested that field calibration might be necessary for optimal measurement accuracy. Full article

(This article belongs to the Special Issue Novel Approaches for Assessment and Control of Gaseous Emission Levels at Animal Production Facilities)

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19 pages, 42970 KiB

Open AccessArticle

Airflow Characteristics Downwind a Naturally Ventilated Pig Building with a Roofed Outdoor Exercise Yard and Implications on Pollutant Distribution

by Qianying Yi, David Janke, Lars Thormann, Guoqiang Zhang, Barbara Amon, Sabrina Hempel, Štěpán Nosek, Eberhard Hartung and Thomas Amon

Appl. Sci. 2020, 10(14), 4931; https://0-doi-org.brum.beds.ac.uk/10.3390/app10144931 - 17 Jul 2020

Cited by 8 | Viewed by 2630

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Novel Approaches for Assessment and Control of Gaseous Emission Levels at Animal Production Facilities)

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Review

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15 pages, 1190 KiB

Open AccessReview

On Finding the Right Sampling Line Height through a Parametric Study of Gas Dispersion in a NVB

by E. Moustapha Doumbia, David Janke, Qianying Yi, Guoqiang Zhang, Thomas Amon, Martin Kriegel and Sabrina Hempel

Appl. Sci. 2021, 11(10), 4560; https://0-doi-org.brum.beds.ac.uk/10.3390/app11104560 - 17 May 2021

Cited by 6 | Viewed by 1591

Abstract

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 [...] Read more.

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

_{3}

/CO

_{2}

is evaluated inside a barn in order to assess under which flow conditions the common height recommendation guidelines for sampling points (sampling line and sampling net) of the tracer gas method are most valuable. Our CFD model considered a barn with a rectangular layout and four animal-occupied zones modeled as a porous medium representing pressure drop and heat entry from lying and standing cows. We studied three inflow angles and six combinations of air inlet wind speed and temperatures gradients covering the three types of convection, i.e., natural, mixed, and forced. Our results showed that few cases corresponded to a nearly perfect gas mixing ratio at the currently common recommendation of at least a 3 m measurement height, while the best height in fact lied between 1.5 m and 2.5 m for most cases. Full article

(This article belongs to the Special Issue Novel Approaches for Assessment and Control of Gaseous Emission Levels at Animal Production Facilities)

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16 pages, 1414 KiB

Open AccessReview

Review of Wind Tunnel Modelling of Flow and Pollutant Dispersion within and from Naturally Ventilated Livestock Buildings

by Štěpán Nosek, Zbyněk Jaňour, David Janke, Qianying Yi, André Aarnink, Salvador Calvet, Mélynda Hassouna, Michala Jakubcová, Peter Demeyer and Guoqiang Zhang

Appl. Sci. 2021, 11(9), 3783; https://0-doi-org.brum.beds.ac.uk/10.3390/app11093783 - 22 Apr 2021

Cited by 2 | Viewed by 2361

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Novel Approaches for Assessment and Control of Gaseous Emission Levels at Animal Production Facilities)

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