Portable particle spectrometer

摘要

Methods and systems for characterizing particles in an aerosol are disclosed. A system includes a collection container that utilizes the principles of elutriation to collect particles of selected aerodynamic diameter ranges within a measurement region. A particle detector is used to detect and characterize particles that have settled into the measurement region.

主权项

1. A system for characterizing particles in an aerosol, based at least in part on an aerodynamic diameter of each of the particles, the aerodynamic diameter of a particular particle comprising a diameter of a sphere of unit density and having the same settling velocity as the particular particle, the system comprising:
a collection container comprising: a first end having an opening; a second end, wherein the collection container is configured to be oriented such that an axis of symmetry extending from the first end to the second end is oriented substantially in a direction of gravitational settling of the particles; and a collection container wall extending between the first end and the second end, the collection container wall having an inner surface defining a collection chamber; a first flow device coupled to the second end and configured to provide a first fluid flow from the second end toward the first end, wherein the first fluid flow is configured such that particles having a first aerodynamic diameter settle into a measurement region of the collection tube; a particle detector operatively coupled to the collection container, wherein the particle detector is configured to detect at least one particle within the measurement region of the collection chamber; a housing, wherein at least a portion of the collection container is disposed within the housing, the housing comprising: a first housing end having a cap disposed above, and spaced apart from, the first end of the collection container, the cap having an inlet aperture defined therein; a second housing end; and a housing wall extending downward from the first housing end such that at least a portion of the housing wall is positioned external to, and spaced apart from, the collection container wall, thereby forming a gap between an outside surface of the collection container wall and an inside surface of the housing wall; and a second flow device operatively coupled to the housing and configured to provide a second fluid flow, within the gap, away from the first housing end, thereby creating a fluid stagnation region above the first end of the collection container, wherein the stagnation region comprises a region in which there is no net fluid flow along a direction parallel to the axis of symmetry.