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United States Department of Agriculture

Agricultural Research Service

Title: LARGE ENVIRONMENTAL CHAMBER: AMMONIA RECOVERY CALIBRATION

Author
item Lefcourt, Alan

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 2001
Publication Date: N/A

Interpretive Summary: Ammonia emissions from farms adversely impact the environment and, when combined with sulfur emissions from cars and power plants, result in the formation of particulates in the air that cause health problems. Accurate measurements of ammonia emissions from on-farm buildings and manure processing technologies are critical for establishing equitable regulations sand for effective evaluation of mitigation techniques. However, quantifyin these ammonia losses has proved to be a difficult task. Ammonia losses are normally estimated by measuring the concentration of ammonia in air and multiplying that value times a representative air flow. Inaccuracies in ammonia measurements can result from variations in ammonia concentrations in the air and inaccurate measurement technologies. The corresponding air flow is also difficult to measure. Two environmental factors that have a great impact on ammonia losses are ambient temperature and air flow. To address these issues, a large environmental chamber was constructed where ambient temperature and mass air flow could be precisely measured and independently controlled, and where ammonia can be measured accurately. To validate the use of this chamber for ammonia studies, known quantities of ammonia were released in the chamber from three locations at three air flows. The amount of ammonia that could be recovered was determined by multiplying the average increase in ammonia concentration in the exhaust plenum by the duration of the increase by the air flow. The recovery of released ammonia over 86 trials averaged 105% +/- 1%. Results from this study indicate that the chamber can serve as a valuable tool for quantifying ammonia release from barns and manure processing technologies.

Technical Abstract: The ability to accurately measure ammonia emissions from farms is an important issue both in terms of establishing emissions regulations and for effective evaluation of mitigation techniques. To address this issue, experimental trials were carried out to determine the ability to quantitatively recover ammonia released within a large environmental chamber designed to house six dairy cows or manure processing technologies Ammonia was released over 30 min periods at a range of values (0.1 to 0.7 g/min) from three positions within the chamber. Chamber temperature was maintained at 22.2 deg C. Air flow was maintained at one of three setpoints; 11.25, 15.00, or 22.50 air exchanges per h. The recoveries over 86 trials averaged 105.1 +/- 0.8%. Small increases in measured recoveries were associated with increased air flow and increased amounts of ammonia released. Results from this study indicate that increases in ammonia within the chamber, including short-term increases, can be quantitatively recovered.

Last Modified: 9/1/2014