Influence of Crosswind on Evaporation Mass Transfer and Heat Exchange in High-Level Water-Collecting Natural-Draft Wet Cooling Towers

High-level water-collecting natural-draft wet cooling towers (HNDWCTs) are commonly employed in super-large thermal and nuclear power units. However, research on the effects of crosswinds is still in the exploratory stage. This paper focuses on the fill packing zone and investigates the influence of various crosswind speeds (ranging from 1 m/s to 18 m/s) on convective and evaporation heat transfer processes in the cooling tower. The results indicate that evaporation heat transfer contributes 90% of the total, asserting a predominant role in the thermal performance of the cooling towers. Therefore, this study examines the impact of crosswinds on evaporation mass transfer in HNDWCTs. It has been observed that the "self-reflux" in high humidity region under low wind speeds is the root cause of generating low mass transfer driving force region. As wind speed exceeds 9 m/s, the "high-humidity reflux" transitions to "low-humidity reflux", which makes the local mass transfer driving force rise back up, and helps to promote the evaporation mass transfer process. This transition mitigates the negative impact of crosswinds, resulting in the stabilization of the evaporation mass transfer and heat exchange reduction at approximately 60%.