Air Change Rate Analysis for a Minienvironment Cleanroom

ASHRAE Journal, August 2017

Author:

Kishor Khankari

Abstract:

Mini-environment cleanrooms are commonly employed in the semi-conductor and pharmaceutical industries to create isolated spaces within a cleanroom to provide better control on the cleanliness and operation of the processes. Mini-environments isolate products and operators from each other to avoid any cross contamination. The required airflow to maintain certain level of cleanliness for mini-environment is much less than that of an equivalent large cleanroom. This paper with the help of a virtual cleanroom setup developed using Computational Fluid Dynamics (CFD) simulations describes the impact of reduced supply airflow rates and the location of supply diffuser on the airflow patterns and resulting distribution of particle concentration in the mini-environment cleanroom. These analyses provide valuable insights into the operation of the mini-environment cleanroom and indicate that reduced airflow rates have a little impact on the airflow patterns and particle distribution within the mini-environment chamber. Reduced airflow rates can make the surrounding room dirtier, however, the location of supply air diffusers in the room can significantly affect the airflow patterns and resulting particle distribution in the room. This study demonstrates CFD analysis can be a valuable tool in gaining insights into the design and operation of the mini-environment cleanrooms.