ASABE Technical Library - Abstract

Abstract. Closed chamber is a potential method for determining gaseous emission flux from fully open animal operations, while its measuring accuracy is theoretically affected by several key factors. This study evaluated the effects of the wind speeds (0.00, 0.25, 0.50, 0.75, 1.00, 1.50 and 2.00 m s^-1) at the emission surface and deployment duration (1, 1.5 and 2.0 hr) on the measurement accuracy of a closed chamber with its configuration of 300 mm (diameter) x 400 mm (height) by using sulfur hexafluoride (SF₆) as a reference gas. Results showed measured emission rates with chamber technique were overall in agreement with, while generally underestimated the reference flux under the laboratory condition. No statistical difference was found among various wind speeds (P˃0.05), revealing measurement accuracy was not affected by wind speeds under 2.0 m s^-1 when measuring the gas emissions from open sources using closed chamber technique. Measured fluxes were averagely 11.98 %, 1.75 %, 2.71 % and 5.25 % lower than reference fluxes under the development durations of 0.5 hr, 1.0 hr, 1.5 hr and 2.0 hr, respectively. It is concluded that the development duration significantly impacts the measurement accuracy of the non-steady state through-flow chamber (P<0.05), while the wind speed of the emission surface does not (P>0.05). The closed chamber with a deployment duration of 1 hr is recommended to measure the GHGs and other gaseous emissions from the open animal operations under relatively low surface wind speeds.