Because some designers of aerosol transport systems use the assumption that aerosol penetration through a system is maximized if the flow Reynolds number is 2,800, we have conducted tests to determine if such an assumption is appropriate. Although we do not believe that optimal performance of an aerosol sample transport system can be presented solely in terms of the Reynolds number, we have presented our results in terms of that parameter to compare our work with the results of an earlier study. Two types of experiments were performed. First, the penetration of liquid aerosol particles through horizontal tubes was experimentally investigated for a range of design and operational conditions. For a particle size of 10 microm aerodynamic diameter, the maximum penetration through a 6.7 mm diameter tube was associated with a Reynolds number of approximately 2,000; the maximum penetration through a tube of 15.9 mm occurred at a Reynolds number of about 3,000; and the maximum penetration through a 26.7 mm diameter tube occurred at about 4,000. It was also experimentally demonstrated that for a fixed flow rate through a horizontal tube, there is an optimum tube diameter for which the aerosol penetration is a maximum. An early study dealing with aerosol particle penetration through a 16.8 mm inside diameter loop of tubing (two vertical tubes, two horizontal tubes and three 90 degrees bends) suggested there was a fixed Reynolds number for optimal aerosol penetration independent of particle size. Those experiments were repeated here and the agreement with those tests is excellent; namely, the maximum penetration through a loop of 15.9 mm diameter tube occurs at a Reynolds number of approximately 2,800, independent of particle size. However, when the tube diameter of the transport system layout was changed to 26.7 mm, the Reynolds number associated with maximum penetration varied for different particle sizes, occurring at Reynolds numbers of approximately 5,600 for 8 microm AD particles, 3,800 for 10 microm particles and 3,000 for 15 microm particles.
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