Empirically based techniques have now been used for many years in calculating the required air flow rate to achieve a certain standard of cleanliness class or to compensate heat loads within the space. Over the years, however, the figures thus calculated have had margin upon margin added to them with the result being that many systems are over-designed with capital and operating costs far in excess of what they would have been for a more optimized design. This paper outlines a method for the optimization of cleanroom design using airflow modeling techniques called computational fluid dynamics (CFD). To a large extent, these techniques, dispense with these historical calculations and allow each new design to be treated as just that without having to rely entirely on experiences from the past or mock-ups of the space being designed. The work presented in this paper is based on an actual project. In the first instance a cleanroom was modeled using air flow rates determined through empirical techniques based on heat loads to the space from machinery and occupants. A sensitivity study was then carried out to assess the effect of optimizing air flow strategy to and from the space.

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