Validation of ammonia emissions from dairy cow manure estimated with a non-steady-state, recirculation flux chamber with whole-building emissions

A non-steady-state flux chamber with recirculation airflow was constructed and coupled with a portable photoacoustic multi-gas analyzer to determine ammonia emissions from dairy manure. The objective of this work was to validate this flux chamber system by performing a comparison between the flux chamber emission rates and whole-building emission rates calculated from an ammonia balance in a mechanically ventilated experimental test room. It was found that flux chamber emission estimates were greatly improved with the addition of internal air recirculation to provide air velocity over the enclosed manure surface. Validation tests of the recirculation flux chamber showed a 9% to 37% underestimation of the emissions calculated from the ammonia balance (R ² = 0.72). The non-steady-state, recirculation flux chamber method can be used to estimate ammonia emissions in naturally ventilated buildings with an accuracy comparable to other available methods. However, the validation tests showed high variability in the results, which is thought to be associated with the different consistency of the manure used in the experiments and the airflow dynamics over the enclosed manure surface.