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NCT 109

Crossflow vs. Counterflow Comparison

ParameterCross FlowCounter Flow
Air/Water FlowPerpendicular (90°)Opposite (parallel but opposite)
FootprintLarger for same capacityMore compact
Pump HeadLower (gravity distribution at lower height)Higher (water pumped to top)
Air Pressure DropLowerHigher
MaintenanceEasier (accessible basins/fills)Harder (nozzles/fills enclosed)
Freeze ProtectionBetter (peripheral exposure)Requires careful design
Water QualityTolerates dirtier waterRequires cleaner water
Typical UseHVAC, medium industrialHigh-efficiency industrial, space-constrained

Applications

  • Commercial & institutional HVAC systems
  • Medium-capacity industrial cooling
  • Power plant auxiliary cooling
  • Geothermal plants
  • Situations where water treatment is limited

Efficiency Factors

  1. Fill Media Type: Splash fills (common) vs. film fills (higher efficiency but prone to fouling).
  2. Air Inlet Design: Louver design affects uniform airflow distribution.
  3. Basin Design: Ensures even water loading across fill.
  4. Approach Temperature: Difference between cold water temperature and wet-bulb temperature (typically 4-6°C).

Key Design Considerations

  • Uniform Air Distribution: Critical to prevent “hot spots” in fills.
  • Wind Effects: External wind can disrupt airflow; wind walls may be needed.
  • Water Load Variations: Distribution basins must handle flow variations.
  • Material Selection: PVC fills, GRP basins, and corrosion-resistant metals.