The Paradox of Mixing in Industrial Ventilation

Details

• Personal Author:
  Bennett J ; Feigley C ; Khan J ; Lee E
• Description:
  Deviations of dilution ventilation equations often assume that a workroom is well-mixed. A flow rate requirement computed using one of these equations is then multiplied by a safety factor, the portion of which accounting for deviations from complete mixing has been called the mixing factor (Km). Here the scale (S) and intensity of mixing (I) were determined for full-scale experiments at 2 Reynolds numbers and 2 Archimedes numbers, and for computational fluid dynamic simulations of workrooms of various configurations and 5 Reynolds numbers under steady, isothermal conditions. The relationships among Km S, and I were explored. In general, the Km required decreased with increased mixing. A cursory consideration of these results suggests increasing mixing to reduce the Km value, and thus the required flow rate. However, this is isadvisable if increasing room air movement might interfere with other exposure control methods that rely on keeping incoming clean air and source emissions segregated. [Description provided by NIOSH]
• Subjects:
  Air Movements Air Pollutants, Occupational Occupational Health Safety Ventilation Workplace
• Keywords:
  Air-flow Air-purification Exhaust-ventilation Industrial-ventilation Models Simulation-methods Ventilation-systems Work-environment
• Publisher:
  American Industrial Hygiene Association
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• Place as Subject:
  California ; Ohio ; OSHA Region 4 ; OSHA Region 5 ; OSHA Region 9 ; South Carolina
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  DART - Division of Applied Research and Technology
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  24
• NIOSHTIC Number:
  nn:20022362
• Citation:
  American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California. Fairfax, VA: American Industrial Hygiene Association, 2002 Jun; :24
• Federal Fiscal Year:
  2002
• Performing Organization:
  University of South Carolina at Columbia, Columbia, South Carolina
• Peer Reviewed:
  False
• Start Date:
  20010901
• Source Full Name:
  American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California
• End Date:
  20050831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:61b20ca01648572ef73d9876fca3981b20e0eb9a73f039526147a3562250cfcffc623650de48425f05f19f8d49d20d312d798cc9b65786fb97dd5c14ff3246df
• Download URL:
  https://stacks.cdc.gov/view/cdc/199166/cdc_199166_DS1.pdf
• File Type:
  [PDF - 501.10 KB ]