Constructing a reasonable reaction kinetic model for Cr-containing waste incineration is of high significance to study the effect of various factors,such as temperature,Cl,on its hexavalent chromium compounds.In this paper,a primary Cr/H/Air/Cl reaction kinetic model is built and studied by Gaussian 03 code with quantum chemistry theory.Numerical results show that there are two overall reactions in the model,each of the two overall reactions consists of their respective two elementary reactions.So the two overall reactions should be omitted from the model.Instead,the four elementary reactions should be added in the Cr/H/Air/Cl reaction kinetic model.The activation energies of the four elementary reactions are also calculated.
The collision frequency function for aerosol particles has already been calculated for the free molecule regime and for the continuum range. The present work, taking into account the influence of internal force fields such as magnetic force, electric force and molecular forces, created by particles themselves, recalculated the collision frequency in the case of particles much smaller than the mean free path of the gas （free molecule regime）. Attractive forces increase naturally the collision frequency, while repulsive forces decrease it. The calculation was performed for all types of central forces deriving from a potential, including Coulomb forces and Van der Waals forces.
In a laminar pipe flow, thermophoretic deposition occurs when the temperature of the pipe wall is less than the temperature of the fluid. For a horizontal pipe, gravity has a significant effect on the deposition of aerosol. Due to the laminar flow of gas fluid, a lift force is imposed on the particle and could affect the deposition of aerosol. In the present work, we considered the influences of various factors on the deposition of aerosol, including diffusion and convection, thermophoresis, gravi- tational settling and the lift force effect. The revised semi-implicit method for pressure-linked (SIMPLER) was employed to solve the aerosol transport equation. The deposition efficiency of aerosol in a pipe was obtained and the concentration distribution of aerosol at an arbitrary cross-section of pipe was given. The results reveal that when gravitational settling was considered the deposition efficiency had a minimum, corresponding to the penetration efficiency having a maximum. For large particles, the deposition of aerosol was dominated by external forces, and the critical particle trajectory method (CPTM) was used to analyze the deposition of aerosol with the action of thermophoretic force and gravity. The result from CPTM coincided very well with the result from SIMPLER.
The deposition of particles in turbulent pipe flow was investigated in terms of two mechanisms, turbulent and thermophoretic. A general equation incorporating these two mechanisms was formulated to calculate the deposition efficiency of aerosol particles in turbulent pipe flow together with thermophoretic deposition. The validity of the equation was confirmed by good agreement between calculated and measured results.
