Numerical Simulations Of Heat And Mass Transfer In Biofilter

There was heat and mass transfer in the biofilter media, as a result of microorganism metabolism activity, the properties of air flow and those of packing material, which made the system run unstable. The aim of this research was to develop a model for heat and mass transfer in a biofilter, and to investigate the migration of temperature and moisture under one-dimensional condition with an emphasis on factors affecting the moisture migration, so as to provide adequate data for the design and operation of a full-scale biofilter system.Firstly, a heat and mass transfer model was set up based on porous media volume-averaging model and three-parameter model. The operator splitting algorithms and the finite element method developed by Galerkin were adopted to deduce the discrete equations. The numerical values of one-dimensional model for heat and mass transfer of media in a biofilter system for the treatment of hydrogen sulfide were in good agreement with the experimental data, and all of the correlation coefficients are above 0.9.Secondly, the effects of air flow properties on moisture migration were investigated numerically. The results confirmed that the rate of moisture transportion was in proportion to the logarithm of gas velocity, exponential of temperature and concentration, and negative power of relative humidity, and in the relative order of gas velocity＞temperature＞concentration＞relative humidity.Finally, the effect of moisture on removal efficiency was calculated based on the model, whose result showed that hydrogen sulfide concentration decreased along the biofilter, while increased as time passed. Both the removal efficiency and elimination capacity decreased as moisture of the media decreased. The microbiological relative activity, calculated as the maximum decomposition rate equal to one, increased as moisture of the media increased, and it tended to be one when the moisture was 60%.