Experimental investigation of particle dispersion in cleanrooms of electronic industry under different area ratios and speeds of fan filter units

Abstract Ventilation and air distribution systems for cleanrooms in electronic industry have been overdesigned. Reducing the air supply volume of fan filter units (FFUs) is considered an energy saving measure. However, little is known about the particle removal performances after reduction in air supply volume. In this study, experiments were conducted in a chamber to investigate the effects of reducing air supply volume on the characteristic of particle distribution. The experiments were based on three FFU speed ratios (80%, 50%, and 40%) and four particle source locations (source in the subzone with and without an FFU at the heights of 1.5 m and 1.0 m) at two FFU area ratios (50% and 25%). The results were analyzed using the dimensionless particle concentrations (with respect to ideal mixing condition) in sixteen subzones within the experimental region. It was concluded that (1) the containment effect of air distribution on particle lateral dispersion was weakened with the decrease of air supply volume for FFU area ratios of both 50% and 25%; (2) most subzones have been well protected at an FFU area ratio of 50% (with dimensionless concentrations far below 0.2) regardless of the source location, and at an FFU area ratio of 25% (with dimensionless concentrations far below 0.5) for the particle source under an FFU supply airflow. However, the containment effect has been poor at an FFU area ratio of 25% for the particle source not under an FFU supply airflow regardless of the air supply volume; (3) the working face at a height of 1.0 m was slightly more affected for a source height of 1.5 m compared with a source height of 1.0 m at an FFU area ratio of 50%, while there was no significant difference in the particle removal for both source heights at an FFU area ratio of 25%; and (4) the air supply volume could be reduced by 46.7% (0.2 as the critical value) and 43.8% (0.5 as the critical value), respectively for FFU area ratios of 50% and 25% from the perspective of air distribution effectiveness. This study improves the understanding of characteristics of reduced airflow in cleanrooms.