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Computational Fluid Dynamics Analysis of a Micro-scale Chamber for Measuring Organic Chemical Emission Parameters
Citation:
Edwards, J., C. Huang, AND X. Liu. Computational Fluid Dynamics Analysis of a Micro-scale Chamber for Measuring Organic Chemical Emission Parameters. JOURNAL OF HAZARDOUS MATERIALS. Elsevier Science Ltd, New York, NY, , 0, (2024).
Impact/Purpose:
Material/air partition coefficient, material diffusion coefficient, and convective mass transfer coefficient are critical parameters for controlling emissions of volatile and semivolatile organic compounds from building materials and consumer products in the indoor environment. This study developed and evaluated a new micro chamber test method and a mass transfer model to determine these key parameters. Our study provides a methodology for systematically measuring key emission parameters as part of exposure model inputs. The data generated using this method will reduce the uncertainties in exposure estimation and improve our understanding of critical sources and pathways of human and ecological exposures.
Description:
Computational fluid dynamics simulations are used to model the velocity field and the transport of a passive scalar within a micro-scale chamber used to measure diffusional transport through various building materials. Comparisons of solutions obtained using a steady, laminar flow assumption with velocity measurements obtained from hot-wire anemometry show some discrepancies at lower volumetric flow rates and for smooth test materials. The results improve for higher flow rates and for carpeted test materials, modeled as a porous resistive layer. Calculations involving scalar transport within the upper chamber of the sampling device are performed for different flow rates and Schmidt numbers. The results are used to develop a model for the convective mass transfer coefficient, correlated as a function of the Reynolds and Schmidt numbers as well as the porosity of the carpet. This model is integrated into a steady-state mass transport model for predicting the diffusion of gaseous formaldehyde through various test materials. Predictions of diffusion and partition coefficients for vinyl flooring, gypsum wall board, and carpet are compared with literature data. The results indicate that a perfectly mixed upper part of the sampling device is an adequate assumption.
