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Samer M.,Leibniz Institute for Agricultural Engineering | Samer M.,Cairo University | Ammon C.,Leibniz Institute for Agricultural Engineering | Loebsin C.,State Institute for Agriculture and Fishery MV | And 4 more authors.
Building and Environment | Year: 2012

Experiments were performed to study the ventilation rates in a naturally ventilated animal building through four summer seasons and three winter seasons. The ventilation rates were determined using moisture (H 2O) balance, tracer gas technique (TGT) and CO 2-balance. The statistical analyses were correlation analysis, regression model and t-test. Continuous measurements of gaseous concentrations (NH 3, CH 4, CO 2 and N 2O), temperature and relative humidity inside and outside the building were performed. The H 2O-balance showed reliable results through winter seasons and acceptable results to some extent through summer seasons. The CO 2-balance showed unexpected high differences to the other methods in some cases. The TGT showed reliable results compared to H 2O-balance and CO 2-balance. The air exchange rates (AERs) were 37.2, 61.6 and 63 h -1 through summer seasons, and 40.3, 38.9 and 60.5 h -1 through winter seasons subject to H 2O-balance, TGT and CO 2-balance, respectively. The emission rates through summer seasons, subject to TGT, were 191, 855, 73,877 and 45.6 g d -1 AU -1; and through winter seasons were 88, 463, 55,976 and 47.3 g d -1 AU -1, for NH 3, CH 4, CO 2 and N 2O, respectively. © 2011 Elsevier Ltd.


Samer M.,Leibniz Institute for Agricultural Engineering | Samer M.,Cairo University | Loebsin C.,State Institute for Agriculture and Fishery MV | Fiedler M.,Leibniz Institute for Agricultural Engineering | And 4 more authors.
Energy and Buildings | Year: 2011

Experiments were performed to study the airflow rates (AFRs) in a naturally ventilated building through four summer seasons and three winter seasons. The AFRs were determined using heat balance (HB), tracer gas technique (TGT) and CO 2-balance as averages of the values of all experiments carried out through the different seasons. The statistical analyses were correlation analysis, regression model and t-test. Continuous measurements of gaseous concentrations (NH 3, CH 4, CO 2 and N 2O) and temperatures inside and outside the building were performed. The HB showed slightly acceptable results through summer seasons and unsatisfactory results through winter seasons. The CO 2-balance showed unexpected high differences to the other methods in some cases. The TGT showed reliable results compared to HB and CO 2-balance. The AFRs, subject to TGT, were 0.12 m 3 s -1 m -2, 1.15 m 3 s -1 cow -1, 0.88 m 3 s -1 LU -1, 56 h -1, 395 m 3 s -1 and 470 kg s -1 through summer seasons, and 0.08 m 3 s -1 m -2, 0.83 m 3 s -1 cow -1, 0.64 m 3 s -1 LU -1 39 h -1, 275 m 3 s -1 and 328 kg s -1 through winter seasons. The AFRs are not independent values, rather they were estimated for specific reference values, which are: area, cow and LU as well as rates. The emission rates through summer seasons, subject to TGT, were 9.4, 40, 3538 and 2.3 g h -1 cow -1; and through winter seasons were 4.8, 19, 2332 and 2.6 g h -1 cow -1, for NH 3, CH 4, CO 2 and N 2O, respectively. © 2011 Elsevier B.V.


Samer M.,Leibniz Institute for Agricultural Engineering | Samer M.,Cairo University | Fiedler M.,Leibniz Institute for Agricultural Engineering | Muller H.-J.,Leibniz Institute for Agricultural Engineering | And 5 more authors.
Applied Engineering in Agriculture | Year: 2011

Measuring the ventilation rates and then quantifying the gaseous emissions from naturally ventilated barns is a particularly difficult task and associated with large uncertainties; where no accurate, reliable, and online method is available for ventilation rate measurements. Therefore, the objective of this study was to develop further the tracer gas technique (TG) for ventilation rate measurements through winter seasons. Fifteen field experiments were carried out to study the ventilation rates in a naturally ventilated dairy barn located in North Germany through three consecutive winter seasons. During each field experiment, continuous measurements of gaseous concentrations (NH3, CO 2, CH 4, and N 2O) inside and outside the barn and tracer gas experiments were carried out. Meanwhile, the microclimatic and climatic conditions were measured and recorded. The air exchange rates (AERs) and then the ventilation rates were estimated by the TG and the CO 2-balance which was set as reference method, in this study, for the purpose of statistical analysis. Three factors with two levels each were tested and they are: 85Kr point release source versus 85Kr line release source, average a-values versus sum impulses, selected radiation counters versus all radiation counters; resulting in eight factor combinations. The results were compared with each other by developing a linear regression model and carrying out Pearson correlation analysis. The differences between the reference method and the eight factor combinations were tested using the ANOVA model. The results showed that the best factor combinations were: (1) line release source considering the impulses recorded by selected radiation counters and implementing the sum method of all impulses where high R-square value of 0.82 and reliable parameter estimate of 1.00±0.19 were found for this combination, and (2) point release source considering the impulses recorded by all radiation counters and implementing the sum method of all impulses where high R-square value of 0.91 and reliable parameter estimate of 1.19±0.15 were found for this combination. The average gaseous emissions through the different winter seasons, subject to the reference method, were 2.9, 14.5, 1785, and 1.6 g h -1 AU -1 for NH 3, CH 4, CO 2, and N 2O, respectively. © 2011 American Society of Agricultural and Biological Engineers.


Fiedler M.,Leibniz Institute for Agricultural Engineering | Berg W.,Leibniz Institute for Agricultural Engineering | Ammon C.,Leibniz Institute for Agricultural Engineering | Loebsin C.,State Institute for Agriculture and Fishery MV | And 5 more authors.
Biosystems Engineering | Year: 2013

Air velocity measurements were collected from one horizontal plane across the entire animal occupied zone (AOZ) floor area of a dairy barn. Data recorded from the undisturbed approaching airflow (25° deviation from normal to the sidewall of the building) and an approach flow disturbed by obstacles (surrounding buildings) in front of the barn (at an incident angle of 20° from normal to the building facade) were analysed. The 96.2m long, 34.2m wide and 10.7m high (ridge) building had open sidewalls, wind protecting nets and large openings in both gable walls. The barn, with a loose housing system with freestalls, accommodated 364 dairy cows. The outside temperatures were between 10 and 20°C, and the outside wind speeds were between 0.7 and 3.9ms-1. The air speed in the AOZ varied from 0.2 to 1.4ms-1. Differences between single areas inside the barn were large and led to different climatic conditions for different animal groups. The undisturbed approaching airflow (at an incident angle of 25° from normal) resulted in a heterogeneous airflow pattern inside the barn with no defined outlet. This airflow pattern was probably influenced by the surrounding buildings on the leeward. In contrast, the disturbed approaching airflow (with obstacles at the windward side) resulted in a homogeneous flow pattern with a lower airflow. A linear model showed that only the interaction between the outside wind speed and the outside wind direction significantly influenced the inside air velocity. Long term measurements at or above the AOZ are needed to complement existing data. © 2012 IAgrE.


Saha C.K.,Leibniz Institute for Agricultural Engineering | Saha C.K.,Bangladesh Agricultural University | Ammon C.,Leibniz Institute for Agricultural Engineering | Berg W.,Leibniz Institute for Agricultural Engineering | And 4 more authors.
Biosystems Engineering | Year: 2013

Natural ventilation (NV) of buildings refers to the exchange of indoor air with outdoor air due to pressure differences caused by wind and/or buoyancy. Increased knowledge of the factors that affect NV and emissions from naturally ventilated dairy (NVD) buildings may lead to a better understanding of indoor air quality, an improvement of emission abatement technologies and a refinement of emission models. The influence of external wind speed and direction on point concentration, air change rate, ammonia (NH3) and methane (CH4) emissions was evaluated in an NVD building located in northern Germany. The measured data were classified according to four wind direction groups: 0°-10° (N), 85°-95° (E), 175°-185° (S), and 265°-275° (W), with consideration for similar wind frequencies and representation of each major side for further analyses and comparisons. The results showed that wind speed and wind direction had significant influence on air change per hour (ACH) (P < 0.05) both individually and when interacting. In contrast, only wind speed and interactions of external wind speed and direction significantly affected NH3 and CH4 emissions (P < 0.05). The surrounding obstacles, other climate parameters (temperature and relative humidity) and other emission sources should be taken into account when interpreting the effects of wind direction on ACH and emissions. Empirical models for ACH, NH3 and CH4 emissions were developed. Intensive experiments in the lab (e.g. scale model in boundary layer wind tunnel) and long-term measurement including all seasons at full scale are required to establish a good empirical model. © 2012 IAgrE.


Saha C.K.,Leibniz Institute for Agricultural Engineering | Saha C.K.,Bangladesh Agricultural University | Ammon C.,Leibniz Institute for Agricultural Engineering | Berg W.,Leibniz Institute for Agricultural Engineering | And 5 more authors.
Science of the Total Environment | Year: 2013

Understanding seasonal and diel variations of ammonia (NH3) and methane (CH4) emissions from a naturally ventilated dairy (NVD) building may lead to develop successful control strategies for reducing emissions throughout the year. The main objective of this study was to quantify seasonal and diel variations of NH3 and CH4 emissions together with associated factors influencing emissions. Measurements were carried out with identical experimental set-up to cover three winter, spring and summer seasons, and two autumn seasons in the years 2010, 2011, and 2012. The data from 2010 and 2011 were used for developing emission prediction models and the data from 2012 were used for model validation. The results showed that NH3 emission varied seasonally following outside temperature whereas CH4 emission did not show clear seasonal trend. Diel variation of CH4 emission was less pronounced than NH3. The average NH3 and CH4 emissions between 6a.m. and 6p.m. were 66% and 33% higher than the average NH3 and CH4 emissions between 6p.m. and 6a.m., respectively for all seasons. The significant relationships (P<0.0001) between NH3 and influencing factors were found including outside temperature, humidity, wind speed and direction, hour of the day and day of the year. The significant effect (P<0.0001) of climate factors, hours of the day and days of the year on CH4 emission might be directly related to activities of the cows. © 2013 Elsevier B.V.


Fiedler M.,Leibniz Institute for Agricultural Engineering | Saha C.K.,Leibniz Institute for Agricultural Engineering | Ammon C.,Leibniz Institute for Agricultural Engineering | Berg W.,Leibniz Institute for Agricultural Engineering | And 4 more authors.
Environmental Engineering and Management Journal | Year: 2014

Air flow measurements as well as concentration measurements within a naturally ventilated dairy barn (NVD) were carried out during one summer season of 2012. Air flow measurements were performed using ultrasonic anemometers (UA), either as short duration (20 min duration) measurements with a higher spatial distribution (using up to 9 UAs at the same time) or as long period (roughly 2 weeks) measurements with a lower spatial resolution (3 to 5 UAs). Measurements were conducted at two heights, at 1.5 m within the animal occupied zone (AOZ) and at 2.6 m height above the AOZ for understanding the distribution of airflow within the building. The three wind components (u, v and w) were measured either as lateral profile or evenly distributed at the ground area of the building. The results showed that wind speeds measured at the height 2.6 m were generally smaller than wind speeds measured at the height 1.5 m. The analysis of the lateral profile showed that only the first third of the wind facing side seem to benefit from the approaching wind. The long term measurements (duration 2 weeks) showed a high variability in the data and a correlation analysis showed lower CO2 concentrations for higher wind speeds. However, the linear correlation was weak (p= -0.7), which implies that the relationship cannot be described simply by a linear correlation. © 2014, (publisher). All rights reserved.


Samer M.,Leibniz Institute for Agricultural Engineering | Samer M.,Cairo University | Muller H.-J.,Leibniz Institute for Agricultural Engineering | Fiedler M.,Leibniz Institute for Agricultural Engineering | And 5 more authors.
Biosystems Engineering | Year: 2011

Experiments were performed to study air exchange rates (AER) occurring in naturally ventilated dairy buildings during summer seasons 2006 to 2010. A tracer gas technique (TG) for AER measurements was developed. The AERs were determined by decay of radioactive tracer Krypton-85, and CO2-balance used as the reference method (RM). During each experiment, continuous measurements of gaseous concentrations (NH3, CO2, CH4 and N2O) inside and outside the building and 85Kr tracer gas experiments were performed. The combined factors investigated were release over feeding table (a1) or over the manure alley (a2), average α-values (b1) or the sum of impulses (b2), selected radiation counts (c1) or all radiation counts (c2). The results were compared using Pearson correlation analysis, developing a linear regression model, and testing the differences between the factor combinations and the RM using an ANOVA model. There were differences between impulses (Pr > |t| = 0.0013), where the sum of impulses showed better results than the average α-values. Although there was no difference (Pr > |t| = 0.344) between the readings of the radiation counts, it was considered that by using all the readings of the radiation counters it was more representative and easier to calculate the AER. The best factor combinations, having the highest coefficient of determination values R2, and the most reliable parameter estimates, were: a1b2c2 (R2 = 0.94; 1.63 ± 0.14); and a1b1c1 (R2 = 0.97; 2.03 ± 0.11). The gaseous emissions, subject to the RM, were 3.9, 19, 1656, and 0.96 g h-1 AU-1 (AU is animal unit of 500 kg) for NH3, CH4, CO2 and N2O respectively. © 2011 IAgrE.


Samer M.,Leibniz Institute for Agricultural Engineering | Samer M.,Cairo University | Berg W.,Leibniz Institute for Agricultural Engineering | Muller H.-J.,Leibniz Institute for Agricultural Engineering | And 5 more authors.
Transactions of the ASABE | Year: 2011

Animal housing is a major source of gaseous emissions, such as ammonia (NH 3), methane (CH 4), nitrous oxide (N 2O), and carbon dioxide (CO 2). Ammonia is an atmospheric pollutant and responsible for eutrophication and soil acidification, while CO 2, CH 4, and N 2O are greenhouse gases (GHG) that contribute to global warming. The quantification of gaseous emissions from livestock buildings with natural ventilation systems is a particularly difficult task and is associated with uncertainties that are largely unknown. One key issue is to measure the ventilation rate and then to quantify the gaseous emissions. Therefore, in this study, the ventilation rate was determined by three different methods simultaneously. Field experiments were carried out to study the ventilation rate in a naturally ventilated dairy barn located in northern Germany during the summer seasons from 2006 to 2010. The air exchange rates (AER) as well as the ventilation rates were determined by the decay of the radioactive tracer krypton-85, the carbon dioxide (CO 2) balance, which was used as the reference method in this study, and the combined effects of wind pressure and temperature difference forces (WT method). Subsequently, the results were compared with each other by carrying out Pearson correlation analysis and developing a regression model. During each field experiment, continuous measurements of gas concentrations (NH 3, CO 2, CH 4, and N 2O) inside and outside the building and 85Kr tracer gas experiments were carried out. Meanwhile, the temperature was measured and recorded inside and outside the barn. Furthermore, the wind velocity was measured. Although the WT method showed minor overestimation by about 1.11 (p < 0.05) times the reference method, it is not reliable because it showed no linear correlation (0.05; p = 0.88) with the reference method. This was due to large fluctuations in the wind velocity (direction and speed), which negatively affected the WT method, which is basically dependent on wind velocity. In contrast, the 85Kr tracer gas technique showed a good linear correlation (0.82; p < 0.05) with the reference method, which accentuates that the 85Kr tracer gas technique is a promising method. However, this technique overestimated the air exchange rate by about 2.05 (p < 0.05) times the reference method. Therefore, the 85Kr tracer gas technique should be further developed to produce values consistent with those estimated by the reference method. The emissions factors, subject to the reference method, were 32, 157.7, 13736, and 7.9 kg year -1 AU -1 for NH 3, CH 4, CO 2, and N 2O, respectively. © 2011 American Society of Agricultural and Biological Engineers.


Samer M.,Leibniz Institute for Agricultural Engineering | Samer M.,Cairo University | Loebsin C.,State Institute for Agriculture and Fishery MV | von Bobrutzki K.,Leibniz Institute for Agricultural Engineering | And 5 more authors.
Computers and Electronics in Agriculture | Year: 2011

Ultrasonic anemometers (USAs) are widely implemented in animal housing to measure the air velocity in different measuring points throughout the whole barn, which ultimately leads to determine the velocity fields and the air flow patterns drawing a clear vision of aerodynamics inside animal buildings. The problem is the timely inconsistent data transmission from the different USAs leading to varied data recording, which makes the comparison between the recorded velocities in different points timely inappropriate. One key issue is to monitor and control the USAs, meanwhile, debug and record the data. Therefore, LabVIEW 8.5, which is a platform and development environment for a visual programming language, was used to configure a computer program to monitor and control the USAs. The principal functions of the system are represented in a main block diagram which consists of 39 sub-diagrams. Five versions of the program were consecutively developed, and then each version was validated and further developed to get the next enhanced version, and so on till Version 5.0. The evaluation and data recording are carried out simultaneously, where the data are transferred from the USAs to the program which detects accidental errors that may have been introduced during data transmission or storage using a checksum algorithm. The developed computer program has been implemented successfully for monitoring and controlling USAs used for carrying out air velocity measurements in livestock housing. Three measurements campaigns were performed to investigate the air profile inside a dairy barn under two conditions, which are "ceiling fans on" and "ceiling fans off", where the average air velocities were 0.98 and 0.59ms -1, respectively. © 2011 Elsevier B.V.

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