Design and Calibration of improved chambers for measurement of gas emissions from tie-stall dairy barns

摘要

Emissions from livestock, such as ammonia and methane gas, are known to contribute significantly to the greenhouse effect. As demand for dairy products increase due to the growing world population, quantifying this effect and developing mitigation strategies becomes increasingly important. Emission of these gasses is highly dependent on cow diet, manure management strategies, barn design and dairy operation. The methodological difficulties of conducting multiple experiments concurrently make this a difficult topic to study experimentally. These difficulties could be overcome if computational models were used to simulate generation and dispersion of chemical species under a number of environmental, design, and experimental treatment parameters. Thisstudy presents a CFD model of ammonia and methane transport within a forced-ventilation tie-stall dairy barn. The model was benchmarked with data collected from four enclosed emission chambers at the USDA-ARS Dairy Forage Research Center in Prairie du Sac, Wisconsin. Experimental data of velocity magnitude and direction were collected along four planes within a representative chamber using an ultrasonic anemometer. Concentration of ammonia and methane were measured after pulse injections using an FTIR gas analyzer in each chamber. Results of this model can be used to explore of the effect of temperature, ventilation, and barn design on gas concentrations.