| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 90 === ABSTRACT
In this thesis we study the moisture purge/dry-down process in a heated curved pipe. Curved pipes constitute a substantial part in gas control modules that are widely used in the semiconductor industry. The purge/dry-down process is essential since semiconductor fabrication processes strictly demand high purity (in particular, low humidity) of the process gases. Also, one of the central issues here is to shorten the purge/dry-down time required to reduce the moisture content of the process gas to a satisfactory level, so as to reduce the equipment warm-up time after regular or accidental maintenance, thereby increasing the average productivity of the equipment.
Here we successfully combine theories of fluid mechanics, heat and mass transfer, and moisture adsorption/desorption dynamics on metals, to develop a complete model for the moisture purge/dry-down process. On the basis of the theoretical model, we carry out systematic numerical simulations of the purge/dry-down process. For a particularly chosen pipe geometry, the effects of wall heat flux and flow rate on the purge/dry-down time are investigated. The numerical results indicate that increasing the wall heat flux would shorten the purge/dry-down time, as it raises the average wall temperature. Meanwhile, for a particular wall heat flux, increasing the flow rate would shorten the time required for the moisture content of the exit gas to reduce to a preset low level. However, since increasing the gas flow rate also has the side effect of cooling down the pipe wall, the time required to completely purge the moisture preexistent in the pipe would actually become longer. These findings are expected to be useful for purge/dry-down process optimization.
|
|---|
