Development of a Sampling Probe with a Small Non-Isokinetic Sampling Error in Variable Flow Velocity Environments

The flow velocity of exhaust gas from an industrial stack varies from facility to facility and can easily change over time, even in a stack. To accurately measure the concentration of fine particles such as PM 10 or PM 2.5 emitted in such environments, the conditions for isokinetic sampling must be satisfied. In this study, a novel sampling probe that generates a small error in particle concentration in variable flow velocity environments was developed, even though isokinetic sampling was not performed. The mass distributions obtained by isokinetic sampling using a conventional sampling probe at a flow velocity of 0–6 m/s were compared with those measured using the developed probe to verify the performance of the proposed probe. It was confirmed that the two mass distributions are similar within an error of 5% under all flow velocity conditions. The mass concentrations estimated through theoretical correction considering sampling loss or gain in non-isokinetic environments were also compared, and the distributions were quite similar within approximately 5%. This verifies that the proposed sampling probe can perform nearly perfect sampling of fine particles without changing the sampling flow rates, with minimal particle under- or overestimation caused by non-isokinetic sampling for variable flow velocity conditions