STUDY ON UNIDIRECTIONAL DOWNFLOW PATTERN WITH CEILING FFUS AND SIDEWALLS RETURNS AND UPPER OUTLETS SEPARATED BY PLASTIC CURTAIN

摘要

Based on the standard k-ε two-equation model, Gambit and Fluent are used to establish and simulate two models with ceiling FFUs and different return configurations to study the downflow pattern in unidirectional cleanroom. Firstly, considering the effect of air-borne particles generated by process equipment, lamps, and operators, the models include the factors and therefore are close to actually operational cleanroom. According to multi-group numerical experiments, returning air from both sidewalls with the coverage higher than 90% and u0 larger than 0.50m/s are necessary for ISO class 1~4. It was found that the measured section of velocity in unidirectional downflow cleanroom should be raised to 0.3m above the separating face from 0.2m, based on the requirement in National Standard GB50591-2010. Furthermore, two formulas between v/v0 and x/r where separating face exists were suggested. Finally, field test in a local unidirectional cleanroom were conducted to verify the simulation results.