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Implementation of Radioactive tracer 85 Kr for Ventilation Rate Measurements in Dairy Barns. 2011 ASABE Annual Meeting M. Samer, W. Berg, M. Fiedler, H.-J. Müller, M. Gläser, C. Ammon, C. Loebsin, O. Tober, P. Sanftleben, R. Brunsch. Introduction.
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Implementation of Radioactive tracer 85Kr for Ventilation Rate Measurements in Dairy Barns 2011 ASABE Annual Meeting M. Samer, W. Berg, M. Fiedler, H.-J. Müller, M. Gläser, C. Ammon, C. Loebsin, O. Tober, P. Sanftleben, R. Brunsch
Introduction • Investigation of emissions from livestock buildings is important as these pollutants affect the health of farmers and the surrounding environment • Emission monitoring enables judgments on the effectiveness of mitigation strategies and controls on emission targets • Quantifying gaseous emissions from naturally ventilated animal buildings is a particularly difficult task and associated with large uncertainties • One aspect is to measure the ventilation rate and then to quantify the gaseous emissions
Methodology • The ventilation rates were determined by two methods: tracer gas technique and CO2-balance • Fifteen field experiments were carried out to study the ventilation rate in a naturally ventilated dairy barn located in North Germany during 3 consecutive winter seasons • During each field experiment, continuous measurements of gaseous concentrations (NH3, CO2, CH4, and N2O) were carried out • Microclimatic and climatic conditions were measured and recorded
Side view of the investigated barn The investigated dairy barn Plan view of the investigated barn
Methodology • The following factors were tested: 85Kr line release source vs. 85Kr point release source, average α-values vs. sum impulses, selected radiation counters vs. all radiation counters • 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
Results The results showed that the best factor combinations were: • Line release source considering the impulses recorded by selected radiation counters and implementing the sum method of all impulses, where high R2 value of 0.82 and reliable parameter estimate of 1.00±0.19 were found • Point release source considering the impulses recorded by all radiation counters and implementing the sum method of all impulses, where high R2 value of 0.91 and reliable parameter estimate of 1.19±0.15 were found
Difference to Reference (h-1) a1b1c2 a1b1c1 a2b1c2 a2b1c1 a1b2c2 a1b2c1 a2b2c2 a2b2c1 Factor Combinations Differences of air exchange rates of the eight factor combinations to the reference method
Results • The average hourly 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 NH3, CH4, CO2, and N2O, respectively • The average daily gaseous emissions were 70, 347, 42853, and 37.5 g d-1 AU-1 for NH3, CH4, CO2, and N2O, respectively
Conclusions • Sum of impulses lead to better results than the average α-values • Considering all readings of the radiation counters is more representative for air movement • Point release source shows better results than the line release source during winter measurements