Particle deposition in ventilation ducts: Connectors, bends anddeveloping flow

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In ventilation duct flow the turbulent flow profile is commonly disturbed or not fully developed and these conditions are likely to influence particle deposition to duct surfaces. Particle deposition rates at eight S-connectors, in two 90{sup o} duct bends and in two ducts where the turbulent flow profile was not fully developed were measured in a laboratory duct system with both galvanized steel and internally insulated ducts with hydraulic diameters of 15.2 cm. In the steel duct system, experiments with nominal particle diameters of 1, 3, 5, 9 and 16 {micro}m were conducted at each of three nominal air speeds: ... continued below

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Sippola, Mark R. & Nazaroff, William W. March 1, 2004.

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In ventilation duct flow the turbulent flow profile is commonly disturbed or not fully developed and these conditions are likely to influence particle deposition to duct surfaces. Particle deposition rates at eight S-connectors, in two 90{sup o} duct bends and in two ducts where the turbulent flow profile was not fully developed were measured in a laboratory duct system with both galvanized steel and internally insulated ducts with hydraulic diameters of 15.2 cm. In the steel duct system, experiments with nominal particle diameters of 1, 3, 5, 9 and 16 {micro}m were conducted at each of three nominal air speeds: 2.2, 5.3 and 9.0 m/s. In the insulated duct system, deposition of particles with nominal diameters of 1, 3, 5, 8 and 13 {micro}m was measured at nominal air speeds of 2.2, 5.3 and 8.8 m/s. Fluorescent techniques were used to directly measure the deposition velocities of monodisperse fluorescent particles to duct surfaces. Deposition at S-connectors, in bends and in straight ducts with developing turbulence was often greater than deposition in straight ducts with fully developed turbulence for equal particle sizes, air speeds and duct surface orientations. Deposition rates at all locations were found to increase with an increase in particle size or air speed. High deposition rates at S-connectors resulted from impaction and these rates were nearly independent of the orientation of the S-connector. Deposition rates in the two 90{sup o} bends differed by more than an order of magnitude in some cases, probably because of the difference in turbulence conditions at the bend inlets. In straight steel ducts where the turbulent flow profile was developing, the deposition enhancement relative to fully developed turbulence generally increased with air speed and decreased with downstream distance from the duct inlet. This enhancement was greater at the duct ceiling and wall than at the duct floor. In insulated ducts, deposition enhancement was less pronounced overall than in steel ducts. Trends that were observed in steel ducts were present, but weaker, in insulated ducts.

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  • Journal Name: Aerosol Science and Technology; Journal Volume: 39; Journal Issue: 2; Related Information: Journal Publication Date: 02/2005

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  • Report No.: LBNL--54843
  • Grant Number: DE-AC02-05CH11231
  • Office of Scientific & Technical Information Report Number: 861228
  • Archival Resource Key: ark:/67531/metadc780625

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Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • March 1, 2004

Added to The UNT Digital Library

  • Dec. 3, 2015, 9:30 a.m.

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  • April 1, 2016, 8:17 p.m.

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Sippola, Mark R. & Nazaroff, William W. Particle deposition in ventilation ducts: Connectors, bends anddeveloping flow, article, March 1, 2004; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc780625/: accessed October 19, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.