How do you evaluate cooling tower performance?

Key performance metrics: Range (water temperature drop = inlet - outlet), Approach (outlet water temperature - wet bulb temperature), and cooling capacity (heat rejected = flow x Cp x range). Tower capability curves show achievable approach at various wet bulb conditions. Performance is evaluated using KaV/L (Merkel number) from test data. Degradation causes: fill fouling/damage, poor water distribution, fan issues, and scaling. Performance improvement: clean/replace fill, optimize water distribution, maintain proper flow rate, and ensure adequate air flow.