Modelling lumped-parameter sorption kinetics and diffusion dynamics of odour-causing VOCs to dust particles

An analytical algorithm is presented for fast simulation of the adsorption kinetics and diffusion dynamics of odour-causing volatile organic compounds (VOC-odour) which originate in the stored swine manure to airborne dust pa rticles in a ventilated airspace. The model is an extension to the well-kno wn lumped-parameter model (LPM) that incorporates a Langmuir-Hinshelwood (L H) kinetic concept dependent on VOC-odour concentration with diffusion limi tation. The basic idea behind the model implementation is to couple the cal culations of the two major processes in the VOC-odour/dust particle system: VOC-odour diffusion based on the homogeneous surface diffusion model (HSDM ) and surface reaction based on the LH kinetics in an LPM scheme. The LPM e mploys Laplace transforms and gamma distributions of the rate coefficient t o produce a lumped-parameter gamma model (LPCM) for kinetic equation of VOC -odour adsorption to airborne dust particles, whereas the HSDM incorporates the age and size distributions of airborne dust for evaluating the dust-bo rne VOC-odour dynamics. The integrate assessment of VOC-odour sorption kine tics and diffusion dynamics allows to relate the adsorption rate coefficien t, reaction order, and surface effective diffusivity in a complex VOC-odour /dust particle system. The LPCM fitted well with the data obtained numerica lly from HSDM and successfully determined the adsorption rate coefficient a nd reaction order for each sorption process. (C) 2001 Elsevier Science Inc. All rights reserved.