How Are Evaporative Condensers Sized for Ammonia Refrigeration?

The capacity basis is the total heat of rejection: the sum of the evaporator loads plus the heat of compression at the design operating conditions — a materially larger number than the refrigeration tonnage alone. The design wet-bulb comes from climate data for the site, selected at a percentile the owner accepts for the few hottest hours, and the condenser selection is checked at both the design point and the part-load points where the plant spends most hours. Multiple smaller units beat one large one for redundancy and for turndown, and the layout provides the clearances the airflow needs — a condenser starved for air by a wall or a neighboring unit never meets its rating.

The recirculating water concentrates dissolved solids as pure water evaporates, so the design provides automated bleed, makeup metering, and chemical treatment for scale and corrosion — specified against the actual makeup water analysis, not a generic program. Biological control addresses the legionella risk inherent in warm aerosol-generating equipment: drift eliminators limit the aerosol, treatment keeps the biology suppressed, and the basin and fill are accessible for the cleaning the maintenance plan requires. The design documents the water and chemical consumption so the owner sees the true operating cost before committing.

An evaporative condenser serves the plant for decades when it is sized for the real heat load and the water is managed as carefully as the refrigeration. The cheapest condenser to buy is rarely the cheapest to own. • Capacity based on total heat of rejection at the site's design wet-bulb • Redundancy and turndown: multiple units with fan staging or variable speed • Water treatment specified from the actual makeup water analysis • Automated bleed and makeup metering holding the chemistry in range • Freeze protection: basin heat or remote sump with a designed winter sequence • Legionella management: drift eliminators, treatment, and cleaning access