DEPOSITION OF AEROSOL-PARTICLES IN DUCTWORK

Many ventilating systems do not function properly due to the fouling o f ducts and components, There is a need to study a wide range of diffe rent duct systems, in order to reduce the deposition I ate in absolute terms, thus arriving at a more efficient system. A preliminary study is conducted in the laboratory to determine the flow behaviour of aero sol particles in relation to the airflow for ducts of various aspect r atios. A constant-injection tracer-gas technique is used to determine the airflow rate in the ductwork. SF6 tracer gas and smoke particles w ere injected at a constant rate into the inlet of each duct and their tracer-gas concentrations in ppm and smoke-particle concentration in m g m(-3) were monitored at various points downstream. Algorithms were e stablished for the deposition rate of smoke particles in various ducts , The results showed that the deposition rate of smoke particles was s trongly influenced by the airflow rate and size of the duct. (C) 1997 Published by Elsevier Science Ltd.