| 摘要 |
Apparatus (1) for generating acknowledged flow (Q), comprising a first passage (2) which is adapted for air flow through the first passage (2) at least partly in essentially vertical direction, i.e. direction aligned with the direction of the force of gravity, a discharge electrode (5) disposed in the first passage (2) for generating airborne unipolar ions (8) in the passage, means for heating (6) or means for cooling (7), adapted to generate a temperature difference within the first passage (2), thereby generating airflow (Q) through the first passage (2), sensing element (12,13), the output of which is a function of the concentration of the airborne electric charge, means (17) for switching or modulating a parameter which affects the output of the sensing element (12,13) and means for determining the volumetric flow (Q) on the basis of the time response which switching or modulation by means (17) for switching or modulating creates to the sensing element (12,13) output. Use of apparatus (1) for determining ultrafine particle concentration. Process for generating acknowledged flow |
