Brehme, Gunnar: Quantifizierung des Luftvolumenstromes in frei gelüfteten Rinderställen mit Hilfe der Kompartimentalisierungsmethode zur Bestimmung umweltrelevanter Emissionsmassenströme

Dissertation (PDF (.pdf), 6679 KB)

Schlüsselwörter
compartment, natural ventilation, air flow calculation and simulation

Sachgruppe der DNB
39 Landwirtschaft, Garten
Basisklassifikation
50.03, 50.33, 43.61
Göttinger Online Klassifikation
YA 000

Dissertation zur Erlangung des Doktortitels, angenommen von: Georg-August-Universität Göttingen, Fakultät für Agrarwissenschaften, 2000-11-23

Abstract

The assessment of airflow volume becomes increasingly important in estimating the environmental impact of airborne stable emissions. In contrast to mechanically ventilated stables the amount of air exchange is irregular in open stables and depends on the natural variables windspeed and wind direction. Statistics on the emission mass flow of natural ventilated stables are not available. An etablished method for the calculation of airflow is based on the measurement of the decay of radioactively marked tracer particles (Krypton 85) in the stable atmosphere at different points. In general the decay behavior can be judged by the air change rate and further by the air flow. The main disadvantage of this method is that the airflow is calculated by averaging the average air change rate of the measured values. But this only holds true if the averaged air change rate is averaged over equal time periods. A condition that is not garanteed. In addition this method assumes that the wind direction is constant during the whole measuring time - a condition that is not valid in practice. To overcome these disadvantages a new calculation method is designed to improve the quality of the results of air flow determination. By dividing the open stable into different compartments it is possible to develop a set of equations describing the complete mass flow. An equation is derived for each virtual compartment in relation to its neighboring compartments. The equations of all compartments are taken for one period of time comprise one time step. The air change between the compartments and the surrounding is described by transfer coefficients. In addition for each time step a local flow pattern is generated for the interior of the stable. The flow pattern chart changes during each time step according to the wind velocities and wind direction.

Niedersächsische Staats- und Universitätsbibliothek Göttingen
37070 Göttingen

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