Evaluation of a proposed area equation for improved exothermic process control.
McKernan-JL; Ellenbecker-MJ; Holcroft-CA; Petersen-MR
Ann Occup Hyg 2007 Nov; 51(8):725-738
Our understanding of heat transfer and meteorological theories and their applications for engineering control design have been refined since the collective work in ventilation engineering for manufacturing process was published by Hemeon in 1955. These refined theories were reviewed and used to develop a newly proposed equation to estimate buoyant plume area (A). The area is a key parameter in estimating the plume volumetric flow (Q = A) required for exothermic process control. Subsequent to developing a theoretical equation for plume area (A), plume velocity and area data were collected in the laboratory using a thermal anemometer and a scale-model exothermic process. Laboratory results were compared to solutions provided by the proposed, American Conference of Governmental Industrial Hygienists (ACGIH) and Hemeon plume area equations to determine which equation most closely matched the laboratory data. To make this determination, either t-tests or Wilcoxon signed-rank tests were conducted (based on examination of data normality) to determine the difference between collected data and solutions from the proposed, ACGIH and Hemeon equations. Median differences and P-values from Wilcoxon signed-rank tests (non-parametric) indicate that the ACGIH and Hemeon plume area equations provide significantly lower values than the laboratory data. However, the proposed equation provided solutions that were not significantly different from the collected data. Results indicate that the plume area equations currently recommended by the ACGIH and Hemeon are not as accurate as the proposed equation over the range of parameters investigated.
Control-technology; Controlled-atmospheres; Controlled-environment; Engineering-controls; Ventilation; Ventilation-equipment; Ventilation-systems; Air-conditioning; Air-filters; Air-quality-control; Air-treatment; Volumetric-analysis; Laboratory-equipment; Laboratory-testing; Statistical-analysis; Qualitative-analysis; Quality-control; Heat; Heat-regulation; Heating-equipment; Combustion-chambers;
Author Keywords: engineering controls; heat and cold; hot processes; local exhaust; ventilation
John L. McKernan, Division of Surveillance, Hazard Evaluation and Field Studies, National Institute for Occupational Safety and Health, 4676 Columbia Parkway, MS-R14, Cincinnati, OH 45226
Annals of Occupational Hygiene