Using a combined power law and log-normal distribution model to simulate particle formation and growth in a mobile aerosol chamber

摘要

We present the combined power law and log-normal distribution(PL+LN) model, a computationally efficient model to be used in simulationswhere the particle size distribution cannot be accurately represented bylog-normal distributions, such as in simulations involving the initial stepsof aerosol formation, where new particle formation and growth occursimultaneously, or in the case of inverse modeling. The model was evaluatedagainst highly accurate sectional models using input parameter values thatreflect conditions typical to particle formation occurring in the atmosphereand in vehicle exhaust. The model was tested in the simulation of a particle formationevent performed in a mobile aerosol chamber at Mäkelänkatu street canyonmeasurement site in Helsinki, Finland. The number, surface area, and massconcentrations in the chamber simulation were conserved with the relativeerrors lower than 2 % using the PL+LN model, whereas amoment-based log-normal model and sectional models with the same computingtime as with the PL+LN model caused relative errors up to 17 and79 %, respectively.