Best Practice for Energy Efficient Cleanrooms:Minienvironments

摘要

Cleanroom air-recirculation systems typically account for a significant portion of the HVAC energy use in cleanrooms. High electric power density is normally required for fans to deliver large volume of airflows that were designed, supplied, recirculated, and exhausted within a given time. With the increasing demand for specific contamination control, it is important to optimize design of clean spaces. Best practice in cleanroom air system design includes right-sizing the systems in cleanrooms and adopting minienvironments. Implementing and integrating minienvironments in cleanrooms can improve contamination control and save significant energy. A minienvironment is a localized environment created by an enclosure to isolate a product or process from the surrounding environment. The advantages in using minienvironments include the following: (1) Minienvironments may create better contamination control and process integration. (2) Minienvironments may maintain better contamination control by better control of pressure difference or through use of unidirectional airflows, e.g., cleanliness-class upgrade required for certain process. (3) Minienvironments may potentially reduce energy costs. The use of fan-filter units (FFU) in minienvironments is common. The energy efficiency of such air-delivery systems can vary significantly because of the difference in energy performance, airflow paths, and operating conditions. Simply adding minienvironments with fan-filter units in an existing cleanroom will increase power density and energy intensity for delivering airflow in the space served, if everything else is unchanged. However, by considering contamination control requirements in the various spaces minienvironments can be integrated with the surrounding cleanroom to optimize the overall electric power demand for the facility and to achieve specific cleanliness in each area. In addition, selecting energy efficient minienvironment systems will further improve the overall energy efficiency of the clean spaces.