Evaluation of multi-channel annular denuders for a newly developed ultrafine particles (UFPs) sampling system

摘要

Laboratory studies evaluated the gas collection efficiency and particle transmission efficiency for multi-channel annular denuders (1, 3, 5, 8-channel) under simulated atmospheric condition to combine with an annular denuder-filter pack (AD-FP) system for a newly developed inertial classification. The multi-channel denuders having large surface area were considered for the AD-FP system since the inertial classification system required having a flow rate of 40 L/min. Gas collection efficiency was measured with phosphorous acid coated denuders targeted on ammonia gas for each denuder. Particle transmission efficiency was determined for ammonium sulfate particles ranging from 0.02 to 0.3 Hm generated by atomizer. Gas collection efficiencies for 1, 3, 5, 8-channel denuders were 96.3%, 98.6%, 98.2%, 98.3% (lch < 3ch < 5ch < 8ch) respectively. The extraction efficiency was over 96% for all denuders except for 8-channel denuder (92%). And the gas collection efficiency was nearly equivalent to the predicted gas collection efficiency and also there was no breakthrough for 6-hour sampling duration. Particle transmission efficiency for 1, 3, 5, 8-channel denuders at 40 L/min were 97.3%, 97.4%, 94.7%, 93.4% (8ch < 5ch < lch and 3ch) respectively. These results indicated that 1 or 3-channel denuders can be effectively applied for the AD-FP system.