Modeling particle fate in ventilation system—Part II: Case study

Abstract

In this paper the particle filter group model, which was presented in the first part of this series of study, is employed to predict particle fate in a typical ventilation system. The model simultaneously takes into account the interactions between particle transport in ventilation ducts and rooms and particle spatial distribution. It has been proven that an entire ventilation system, including filters, ducts and rooms, can be regarded as a serial of filters in steady-state cases, hence the name “particle filter group model”. With this model, the particle concentration and quantity of deposited particles in each part of the ventilation system can be easily calculated. The four possible fates of particles in a ventilation systems are as follows: (i) filtered/captured by a filter, (ii) exhausted via exhaust, (iii) deposited in ventilation ducts and (iv) deposited in the ventilation room. Each of these particle fates is analyzed. Four factors that may affect particle fates within the ventilation system are the fresh air rate, efficiency of the filter, type of ventilation duct (roughness) and ventilation modes. These are also analyzed. Results indicate that the fates of particles from outdoor air and indoor particle sources differ significantly. It was found that particle sizes were an important determinant in particles’ fates within a ventilation system.