Models for nearly every occasion: Part II - Two box models.

Area of Science:

• Industrial Hygiene
• Environmental Engineering
• Occupational Health

Background:

• Traditional "well-mixed room" two-box models are limited to scenarios without local exhaust controls.
• Predicting contaminant concentrations is crucial for workplace safety and exposure assessment.

Purpose of the Study:

• To present new two-box models that incorporate local exhaust controls, including outside exhaust and filtered air recirculation.
• To develop models for both steady-state and transient conditions, accommodating cyclic and irregular emission patterns.
• To introduce a structured calibration procedure for model validation in diverse work scenarios.

Main Methods:

• Development of new two-box models incorporating local exhaust and filtered air recirculation.
• Inclusion of an emission fraction factor for cyclic and irregular emission patterns.
• Introduction of variables for local control capture efficiency and filtration efficiency.
• Presentation of a structured model calibration procedure.

Main Results:

• New models accurately predict near and far-field concentrations with local controls.
• Models accommodate scenarios with filtered exhaust returned to the workspace.
• The emission fraction factor simplifies calculations for intermittent contaminant release.
• Calibration procedure estimates unknown variables like generation rate and effective near-field flowrate.

Conclusions:

• The developed two-box models offer enhanced prediction capabilities for workplace contaminant concentrations.
• These models are applicable to scenarios with local exhaust, filtered recirculation, and intermittent emissions.
• The structured calibration procedure ensures model adaptability and accuracy for practical industrial hygiene applications.