A direct method of measuring gaseous emissions from naturally ventilated dairy barns

摘要: Abstract Air pollutant emission rates from mechanically ventilated (MV) dairy barns are determined the product of differences in concentrations pollutants air at inlet and exhaust points corresponding ventilation rates. In contrast to well defined entry exit MV barns, large area inlets or outlets characterize naturally (NV) freestall barns. Complicating this scenario even more, pertinent airflow characteristics (velocity direction) necessary for determining vary continuously, both temporally spatially. This paper describes implementation a direct method, generally equivalent approach used NV Ultrasonic anemometers (sonics) located salient barn openings mapped inflow outflow velocities calculate Pollutant entering leaving during given period were measured sampling next anemometers. The were, general, higher than but diurnal profiles similar. observed consistent with prevailing wind directions. inflows predominantly windward barn, while outflows mainly barn's leeward openings. Results indicated that either: (i) average (averaging approach), (ii) (inflow-only approach) credible representations also revealed use an on-site weather station one sonic mounted middle each wall as possible suggested interpolating missing intermittent gas measurements could potentially increase integrity significantly lower capital investment operational costs.