Air Cooler (Unit Cooler): The indoor unit that circulates cold air in a refrigerated space. Contains an evaporator coil, fans, and a casing. Mounted on the ceiling or wall of a cold room, freezer room, or processing area.

Evaporator (Process): A heat exchanger where liquid refrigerant evaporates, absorbing heat from the process fluid (air, water, glycol, or product).

Condenser: Rejects system heat to the ambient environment. Air-cooled condensers use ambient air; evaporative condensers use water evaporation for more efficient heat rejection.

Fin spacing is the critical design parameter for low-temperature air coolers:

• Low temperature (−25 to −40°C, high frost): 6–12 mm fin spacing
• Medium temperature (−5 to −25°C, moderate frost): 4–6 mm
• High temperature (+2 to +15°C, minimal frost): 2–4 mm
• Variable spacing: wider at air entry (heaviest frost), tighter toward exit

Standard: Copper tube, aluminium fin, galvanized casing. For general cold storage.

Food processing: SS304 casing, epoxy-coated aluminium fins. For washdown areas.

Coastal/marine: SS316 casing, epoxy-coated or copper fins. For salt-water environments.

Maximum hygiene: Full SS316 construction. For pharmaceutical or high-acid environments.

EC (Electronically Commutated) motors: 20–30% more efficient than AC. Speed controllable 10–100%. 2–3 year payback through energy savings.

AC shaded-pole motors: Simple, robust, lower capital cost. Fixed speed. Efficiency 50–60%. Budget-constrained applications.

Centrifugal fans: For applications requiring higher static pressure — ducted systems, long air throws.

For low-temperature air coolers, defrost is essential:

• Electric defrost: Heating elements in coil and drain pan. Simple, independent of refrigeration system.
• Hot gas defrost: Hot refrigerant gas directed through evaporator coil. Uses waste heat from refrigeration cycle. Lower operating cost.
• Water defrost: Warm water sprayed over coil. Fast — 8–15 minutes. Requires water infrastructure.