Operational Strategy of Nonuniform Air Supply in Cleanrooms

To ensure that cleanroom cleanliness requirements are met, the current design and operation of cleanrooms generally necessitate the fan filter unit (FFU) to open. However, deploying an excessive number of FFUs may lead to an air volume redundancy problem, which can reduce air volume. Conversely, reducing FFUs and their airflow might also increase the risk of uneven indoor airflow distribution and particle concentration. This study analyzes the influence of the nonuniform operational strategy of FFUs (including the opening rate, arrangement position, and air velocity of FFUs) on the distribution of airborne particulate matter concentration in the cleanroom using CFD simulation technology. Results showed that opening only the top part of the source FFU can significantly reduce the indoor particulate concentration in the cleanroom and maintain the cleanliness that meets the requirements of cleanrooms. In the case of the same number of air exchanges, increasing the air velocity of the upper FFU of the indoor airborne particulate pollution source has a significant effect on the purification of indoor particulate matter in the cleanroom. These results show that the nonuniform air supply from the upper FFU of the source has good purification performance for airborne particles in a typical cleanroom.