Homogeneous Ternary H2SO4-NH3-H2O Nucleation and Diesel Exhaust: a Classical Approach

Abstract

The classical nucleation theory was used to model ternary nucleation at temperatures and concentrations observed in diluting diesel exhaust. The nucleation rate does not markedly depend on the NH3 concentration below the level of 0.8 ppb, with the binary H2O–H2SO4 mechanism dominating. This rules out the effect of dilution air ammonia levels on nucleation mode formation in most cases. On the other hand, with high NH3 concentration in the case of SCR (Selective Catalytic Reduction) technology, we predict a dependence between the ammonia slip and the nucleation mode concentration.