Evaluation of the Influence of Transitional Slot Reynolds Numbers on Ventilation Efficiency in Mechanically Ventilated Enclosures

摘要

We investigated the influence of a set of transitional inlet slot Reynolds numbers (rangingfrom 790 to 4000) on ventilation efficiency for an indoor ventilated enclosure. These slotReynolds numbers are directly related with supplied ventilation rates, corresponding to AirChange per Hour (ACH) 4 to 20. The low-Re-number k– ε model is applied for RANSsimulation in the current study. The maximal local volume-averaged concentration andrecirculation rate are employed to represent ventilation efficiency. We found that whenincreasing inlet velocities, i.e., increasing slot Reynolds numbers, the impact on turbulencelevels and pollutant concentration distributions is considerable. The larger the inlet slotReynolds number is, the smaller the pollutant concentration magnitude will become. Theresults also indicated that pollutant concentration ceases to decrease with the increase of slotReynolds numbers. Moreover, it will be less dependent on the larger range of slot Reynoldsnumbers (for the current study, i.e. Re_s≥ 3000) and will finally tend to show an asymptoticbehavior. These findings will play an important role for the design of energy-efficientventilation systems.