The influence of alternative layouts for air-circulation on airflow patterns in the processing area of a cleanroom

The particle-free conditions provided by cleanrooms are essential for many modern manufacturing industries. Cleanrooms have to be first designed, constructed, and then on-site tested to ensure they achieve their performance specification. The on-site testing needs to be continued repeatedly even at the fully operational stage. In this study, field-testing of cleanrooms looking at parameters such as: airborne particle counts, airflow volume, turbulence intensity, temperature and pressure difference, were carried out under different occupational states in a newly constructed cleanroom. It was found that improved contamination control was needed due to the high particle counts at specific sampling locations. Consequently, a computational fluid dynamics simulation was conducted to investigate airflow characteristics based on the existing field-test results. Improvement strategies with less expenditure were proposed and have been assessed comprehensively. The results from computer simulation showed that an improvement of airflow could be achieved, not only by increasing the number of fan-filter units, but also by better arrangement of the return air grilles at both sides of the cleanroom.