Paper No: 200000 - International Conference of Agricultural ...

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Figure 2. Configuration of the test facility for the cleaning of poultry exhaust air (1: raw gas;2: filter fleece; 3: scrubber wall 1; 4: scrubber wall 2; 5: clean gas; 6: fleece exhaustion; 7: watertank 1; 8: water tank 2; 9: dust removal; 10: elutriation water tank 1; 11: elutriation water tank 2;12: fresh water supply; 13: sulfuric acid supply).ResultsMeasurementsIn the layer keepings ammonia concentrations could be determined between 1 ppm and 30 ppminside the stables. Dust fraction PM4 is found from < 0.1 mg/m³ during the night up to 8 mg/m³at day time mainly affected by the activity of the birds. Specific events raised the production ofairborne pollutants. Manure removal in keepings with manure belts lowered the ammoniaconcentration inside the stable significantly. An example is given in figure 3 for a German smallgroup housing system.Figure 3. Daily course of ammonia concentration in a German small group housing system.4
The composition of the exhaust air from a chicken house showed considerable fluctuations.High ammonia concentrations up to 30 ppm in maximum were observed in March and fromOctober to December. In the period between July and September the average daily values werenearly constant below 5 ppm. As detected in a layer keeping the ammonia emissions showed anoticeable correlation with the weekly dung removal intervals. After dung removal the NH 3emission was very low but increased significantly till the next dung removal. The relativehumidity and temperature varied from 33.5 to 78.2 % and from 18.4 °C to 33.7 °C, respectively.While methane and total organic carbon concentrations below 3 ppm in average, the carbondioxide concentrations were 1,055 ppm in mean and 3,227 ppm in maximum, which is slightlyover the German limit for animals of 3,000 ppm. The hydrogen sulfide concentration was 1.0ppm in average.Computational fluid dynamicsThe calculation results of cases 3b and 4b (cf. figure 1) are visualized in figure 4. Themovement of massless particles (purple) and the concentration distribution at 0.5 m height isshown. The air movement in the centre of the stable is diminished by installation of the aviaries.The internal stable emissions rise in case 4b due to the increase in turbulence.Figure 4. Flow patterns and ammonia distributions of ventilation setups 3b and 4b.In dependency on the arrangements (1a to 4a without aviary frames and 3b to 4b with aviaryframes) the emission factors shown in figure 5 are in the upper part with regard to the animalnumber (red) resp. with regard to the emission area (green). In the lower part the meanconcentration 0.2 m above the internal emission areas of the stable is shown. The stables withlowest emissions are those ones with line sources and sinks.The numerical simulation showed the emission reduction potential with simultaneousconsideration of stable air quality by using smart ventilation systems.Technical meansMeasurements after exhaust air treatment showed a mean particle separation efficiency of atleast 57 % for the 2.0 – 2.5 µm and 98% for the 6.5 – 7.5 µm particle fraction at filter loadingrates from 1,800 to 3,600 m³/(m² h). The nitrogen balance showed a separation efficiency of72 %.5
Page 1 and 2: An ASABE Conference PresentationPap
Page 3: Computational fluid dynamicsIn the

Paper No: 200000 - International Conference of Agricultural ...

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