An industrial evaporative cooler lowers supply air temperature by 4 to 12°C through water evaporation, using only 1.5 to 5 kW of fan and pump power to move 10,000 to 60,000 m³/h of cooled air, making it the lowest-cost cooling option for hot, dry spaces such as factories, warehouses, and workshops. It works by passing warm outside air through water-saturated pads, where evaporation absorbs heat, so the delivered air is cooler and refreshed without refrigerants or compressors.
How an Evaporative Cooler Works
The unit draws outside air with a centrifugal or axial fan and pushes it through cellulose or aspen pads kept wet by a water pump and distribution system. As air crosses the wet surface, water evaporates and the latent heat of vaporization removes energy from the air, dropping its dry-bulb temperature while raising humidity. The cooled air is then ducted or discharged directly into the space. Because no refrigerant cycle is involved, the electrical load is only the fan and pump, typically 1.5 to 5 kW for a 30,000 m³/h unit, versus 30 to 60 kW for a comparable compressor system.
Direct vs Indirect Evaporative Cooling
A direct cooler adds moisture to the supply air, which is fine for spaces where higher humidity is acceptable. An indirect cooler uses a heat exchanger so the air is cooled without gaining moisture, better for comfort where humidity must stay low. Indirect types reach 5 to 10°C of cooling with slightly higher power, while direct types reach 4 to 12°C but raise RH by 20 to 40 percentage points. Two-stage or indirect-direct systems combine both for up to 15°C drop in very dry air.
Evaporative Cooler Comparison
| Type | Temperature drop | Humidity added | Typical power (30k m³/h) |
|---|---|---|---|
| Direct (pad) | 4 to 12°C | Yes, +20 to 40 RH | 1.5 to 5 kW |
| Indirect (plate) | 5 to 10°C | No | 2 to 7 kW |
| Two-stage | up to 15°C | Low | 3 to 9 kW |
The table shows the trade between cooling depth, moisture, and power, guiding the choice by climate and comfort need.
Sizing Guide and Key Numbers
Three numbers drive selection. First, airflow: workshops need 20 to 60 air changes per hour, so a 2,000 m³ hall at 30 ACH requires about 60,000 m³/h. Second, pad face velocity: keep it at 1.5 to 2.5 m/s so water saturates the air without excessive pressure drop of 50 to 150 Pa. Third, water use: a 30,000 m³/h direct unit evaporates 30 to 120 liters per hour depending on temperature and RH. Effectiveness, or saturation efficiency, typically runs 75 to 90 percent for quality cellulose pads.
When to Choose Evaporative Cooling
- Choose a direct evaporative cooler for hot, dry climates where RH stays below 40 to 50 percent and moisture is acceptable.
- Choose an indirect or two-stage unit when you must cool without raising indoor humidity.
- Choose evaporative cooling for large open workshops where refrigerant cost per m³ is prohibitive.
- Choose a compressor or chiller system instead when RH exceeds 60 percent and the drop falls below 4°C.
- Choose a packaged roof-mounted unit for single-zone buildings and a ducted system for zoned control.
Installation and Maintenance
Mount the cooler where it draws clean outside air, not recirculated exhaust, and size duct to keep velocity at 4 to 8 m/s. Provide a water supply of 30 to 120 L/h and a drain for bleed-off to control mineral buildup, which can cut pad life from 3 to 5 years to under 1 year if ignored. Clean pads and the sump each season, descale the distributor, and protect the fan from dust. With care, the unit runs 10 to 15 years and cuts cooling energy by 70 to 80 percent versus refrigerant systems in arid regions.
Keruite manufactures this equipment at an 80,000 m² facility in Dezhou, China, with an in-house AMCA-210-style test laboratory; every unit is balanced to G2.5 and performance-tested before shipment.
Pads, Water, and Saturation
The cooling pad sets both performance and cost. Cellulose pads 100 to 300 mm thick give saturation efficiency of 75 to 90 percent at a face velocity of 1.5 to 2.5 m/s, while aspen wood pads are cheaper but last only 1 to 2 years versus 3 to 5 years for cellulose. Water is distributed by a pump at 30 to 120 L/h for a 30,000 m³/h unit and must be bled off at 5 to 10 percent of flow to stop mineral scaling that can cut pad life from 5 years to under 1. The sump holds 20 to 200 liters depending on size, and a float valve keeps level steady. In very dry air the wet-bulb depression is large, so the 4 to 12°C drop is easy to reach; as RH climbs above 60 percent the drop falls to 2 to 4°C and the added moisture becomes a downside.
System Layout and Operating Cost
Direct discharge units suit open workshops where 20 to 60 air changes per hour flush heat and fumes, while ducted roof units serve zoned buildings with 4 to 8 m/s supply velocity. Because there is no compressor, running cost is 1.5 to 5 kW of fan and pump versus 30 to 60 kW for refrigerant cooling of equal airflow, a 70 to 80 percent saving in arid regions. A 2,000 m³ factory at 30 air changes needs about 60,000 m³/h and uses 60 to 240 L/h of water, which is negligible next to the energy saved. Maintain by cleaning pads each season, descaling the distributor, and winterizing the sump; with care the unit runs 10 to 15 years and stays the cheapest cooling per m³ wherever the climate is hot and dry.
Water Quality and Scaling
Make-up water hardness drives scaling on pads and distributor; above 200 ppm hardness, bleed-off and periodic acid cleaning protect the 3 to 5 year pad life. Softened or recirculated water lowers scaling and can extend life toward 5 years, while hard untreated water can clog a 100 mm pad within a single season and drop saturation efficiency from 85 to below 60 percent.
FAQ
How does an industrial evaporative cooler lower temperature?
It pulls warm outside air through wetted pads where water evaporates, absorbing heat and dropping the air temperature by 4 to 12°C while raising humidity. The cooled air is then delivered by a fan at 10,000 to 60,000 m³/h, providing low-cost cooling wherever the air is dry enough for evaporation to work.
What climate is best for evaporative cooling?
Evaporative cooling works best in hot, dry climates where relative humidity stays below about 40 to 50 percent, such as desert and arid industrial regions. In humid areas above 60 percent RH the temperature drop shrinks to 2 to 4°C and the added moisture can feel uncomfortable, so it is less effective there.
How much water and power does an evaporative cooler use?
A direct unit moving 30,000 m³/h may use 30 to 120 liters per hour of water for evaporation and 1.5 to 5 kW of fan and pump power. That is a fraction of the 30 to 60 kW a refrigerant system would draw for similar cooling, which is why running cost is 70 to 80 percent lower in suitable climates.
What size evaporative cooler do I need?
Size from the space volume and desired air changes, typically 20 to 60 air changes per hour for workshops. A 2,000 m³ factory at 30 ACH needs about 60,000 m³/h. Then confirm the pad area gives a face velocity of 1.5 to 2.5 m/s for full saturation without excess pressure drop.