A transfer function model to describe odor causing VOCs transport in a ventilated airspace with mixing/adsorption heterogeneity

The ability of a transfer function modeling technique is evaluated to expla in the odor causing VOCs (VOC-odor) transport processes influenced by heter ogeneity of adsorption surface of ambient aerosol and air mixing pattern in a ventilated airspace. An advection-reaction impulse/step response functio n is used to generalize the dynamic transport of VOC-odor in heterogeneous mixing/adsorption ventilated airspace. The system process presented by an e nsemble transfer function is solved analytically in the Laplace domain. The model requires the specification of probability density function (pdf) for residence time of airflow and for both equilibrium linear partitioning and first-order mass transfer rate parameters of gas/solid phase to quantify t he specific air mixing pattern and transport processes. The model predicts the ensemble mean VOC-odor concentrations for a variety of adsorption kinet ics and mixing pattern combinations as a function of the boundary impulse/s tep response inputs as well as residence time and adsorption rate statistic s. The general behavior of output VOC-odor profiles is analyzed through the effects of mean adsorption rate coefficient, mean linear partitioning cons tant, mixing efficiency, mean residence time and coefficient of variations of both linear partitioning and rate coefficients. This study indicates tha t when mixing/adsorption heterogeneity exists, simple complete mixing assum ption and simple distribution of rate constant are inherently not sufficien t to represent a more generally distributed mixing/adsorption process of VO C-odor transport in a ventilated airspace. (C) 2001 Elsevier Science Inc. A ll rights reserved.