What are the critical operating parameters for a falling film evaporator?

Critical parameters include: liquid distribution (uniform film formation across all tubes prevents dry spots), feed flow rate (minimum wetting rate prevents film breakdown - typically 0.5-2 kg/m per tube circumference), heating medium temperature (limited by product degradation), vacuum level (lower pressure reduces boiling point for heat-sensitive products), concentration ratio per pass (avoid over-concentration causing viscosity issues), and recirculation ratio (if used, to maintain wetting). Poor liquid distribution is the most common cause of operational problems.