A comprehensive Guide for Selection of Air Washer System for Cooling Efficiency in Factories, Warehouses, Manufacturing Plants March 25, 2025 sazenviro Post in Uncategorized What is an Air Washer?Contents1 What is an Air Washer?2 Technical Components of an Air Washer3 Performance Metrics4 Efficiency Factors – Internal & External4.1 Internal Factors4.2 External/Environmental Factors4.3 Degradation of Efficiency – Examples5 Efficiency Enhancements & Best Practices6 Air Washers Without Condenser or Refrigeration System7 How Do Air Washers Without Condenser Work?8 Operating Conditions & Cooling Range9 Wet Bulb Temperature (WBT) – Theoretical Cooling Limit9.1 Example:10 Applications – Where Non-Refrigerated Air Washers Work Well11 Limitations of Non-Refrigerated Air Washers12 Efficiency Comparison – With vs Without Refrigeration13 Efficiency Optimization Tips (For Non-Refrigerated Air Washers)13.1 13.2 Air Washer System Comparison Chart13.3 References & Sources An air washer is a hybrid air purification and humidification system used in industrial HVAC systems, Warehouses, Factories and Manufacturing Plants to clean and condition air for a pleasant and comfortable working temperature inside the premises. It removes dust, pollen, smoke, and gases, while also cooling and humidifying the air through evaporative cooling. In this post we will discuss about Air Washer System Selection Guide based on Cooling Efficiency, Cost, and Suitability. Technical Components of an Air Washer Component Description Casing Typically made of galvanized iron, stainless steel, or FRP. Designed to be corrosion-resistant. Nozzles/Spray System High-pressure spray nozzles atomize water into fine droplets to wash air. Eliminators/Droplet Separators Remove moisture droplets from air to avoid water carryover. Water Circulation Pump Recirculates water from the sump to the spray nozzles. Cooling Pads (in some models) In cellulose or synthetic form; increase surface area for evaporation. Sump/Water Tank Holds the recirculated water; may include a level sensor and float valve. Air Filter (Optional) Primary air filters (pre-filters) to reduce particulate load. Fan/Blower Draws external air through the washer and supplies to the space. Control System Regulates spray, pump, and fan speed (optional PLC/IoT enabled). Performance Metrics Parameter Typical Range Air Flow Rate 500 CFM to 1,00,000+ CFM Filtration Efficiency 60–95% for particles ≥10 microns Cooling Efficiency 70–90% (evaporative cooling) Pressure Drop 20–100 Pa Humidification Increases RH by 20–60% Water Consumption Varies based on humidity and air flow, typically 5–15 L/min Efficiency Factors – Internal & External Internal Factors Factor Impact Water Quality Poor water quality (high TDS, scaling agents) can clog nozzles and reduce spray efficiency. Nozzle Condition Worn or clogged nozzles reduce atomization, reducing cleaning and cooling. Fan Performance Inefficient or poorly maintained fans reduce airflow and pressure. Pump Pressure Insufficient pressure leads to larger water droplets, reducing surface contact with air. Air Filter Condition Dirty filters increase pressure drop and reduce overall air throughput. Recirculation Water Temp Higher temperatures reduce evaporative cooling efficiency. Maintenance Practices Scale build-up, biofilm, or algae growth reduces thermal exchange and hygiene. External/Environmental Factors Factor Impact Ambient Temperature Higher temperatures increase cooling efficiency due to increased evaporation potential. Relative Humidity (RH) High RH (>60%) reduces the potential for evaporative cooling. Dust/Particulate Load High ambient dust levels increase loading on water and filters, reducing long-term efficiency. Air Velocity & Pressure Incorrect inlet air velocity leads to uneven washing or carryover. Make-up Water Temperature Cooler make-up water improves evaporative cooling and cleaning. Location (Indoor/Outdoor) Outdoor units exposed to sunlight or contaminants need additional protection. Altitude At high altitudes, air density decreases, affecting fan performance and water evaporation rate. Degradation of Efficiency – Examples Issue Efficiency Impact Nozzle clogging due to hard water Reduces spray pattern coverage, lowers air-washing effect High humidity in summer Reduces evaporation, lowers cooling by 20–30% Poor fan maintenance Reduces airflow and increases energy usage Biological growth in sump Blocks nozzles, affects hygiene, introduces foul smell Algae on eliminators Increases pressure drop, reduces air throughput Efficiency Enhancements & Best Practices Use softened or treated water to avoid scaling and nozzle clogging. Install VFDs for blower and pump to optimize energy based on demand. Use corrosion-resistant materials like FRP or stainless steel in harsh environments. Implement regular cleaning schedules (weekly/monthly) for filters, eliminators, and sump. Incorporate automatic TDS controllers and water level sensors. Add UV sterilization or biocide dosing to prevent microbial growth. Use dual-stage filtration: dry pre-filters + wet washing for better efficiency. Air Washers Without Condenser or Refrigeration System These are non-refrigerated air washers, which rely solely on evaporative cooling and air scrubbing using water. They do not include components like: Compressor Condenser coil Refrigerant circuit Expansion valves Instead, they work purely through adiabatic (evaporative) cooling. How Do Air Washers Without Condenser Work? Ambient hot air enters the unit. Water is sprayed or passed through wetted pads using high-pressure nozzles or circulation pumps. As air passes over the water droplets or wet surfaces, it absorbs moisture and loses sensible heat. Cooled, humidified air exits and enters the building/room/duct. No phase change of refrigerant is involved—only water evaporation provides the cooling effect. Operating Conditions & Cooling Range Parameter Range/Condition Ambient Dry Bulb Temp 30°C to 48°C (ideal for dry/hot climates) Ambient Relative Humidity (RH) Less than 55% RH for best performance Cooling Effect (Temp Drop) Up to 8°C to 15°C below ambient DBT Typical Supply Air Temp 18°C to 30°C (depends on RH) Dew Point Cooling Not achieved (unlike refrigerated systems) Best Efficiency In hot & dry conditions (e.g., desert or inland climates) In high humidity conditions (RH > 60%), effectiveness drops significantly—cooling might be only 2–5°C. Wet Bulb Temperature (WBT) – Theoretical Cooling Limit The maximum cooling achievable by a non-refrigerated air washer is limited by the wet bulb temperature of the incoming air. Example: Ambient Air: 42°C DBT, 20% RH WBT: ~22°C Max Cooling: ~20°C drop → Supply air ≈ 22°C Efficiency: Up to 90–95% of the DBT-WBT difference Applications – Where Non-Refrigerated Air Washers Work Well Suitable Application Reason Industrial Shops & Warehouses Large air volumes; low cost cooling Paint Booths Humidified and dust-free air is critical Textile Mills Require humid air for yarn quality Food Storage (Non-refrigerated) Controlled humidity; low-energy cooling Greenhouses Evaporative cooling + humidity control Dry Climates (Desert, Semi-Arid) High dry bulb, low humidity—ideal for evaporation Limitations of Non-Refrigerated Air Washers Limitation Description No Temperature Control Precision Cannot cool below WBT; supply temp varies with ambient Not Suitable for Humid Climates Efficiency drops drastically in coastal or monsoon regions Cannot Dehumidify Instead, it adds moisture to air (raises RH) Dependent on Water Quality Poor water affects efficiency and hygiene Seasonal Performance Works better in summer; limited use in monsoon/winter Efficiency Comparison – With vs Without Refrigeration Parameter Air Washer (No Refrigeration) With Refrigeration (DX/Chiller) Cooling Temp Range ~8–15°C below DBT (up to WBT) Can go below WBT; ~10–20°C chilled air Humidity Control Increases RH Can decrease RH (dehumidification) Power Consumption Low (only pump + fan) High (compressor power) Initial Cost Low to moderate High Best Use Dry & hot areas Precise temp/RH control needed Efficiency Optimization Tips (For Non-Refrigerated Air Washers) Use high-efficiency nozzles with proper droplet size (~50–100 microns). Install two-stage systems: pre-filter + wet washer. Use cool groundwater or chilled makeup water (if available) to improve output temperature. Maintain eliminators and sumps to prevent biofouling and ensure clean air. Install variable frequency drives (VFDs) for fans and pumps to adjust based on ambient load. Monitor and control TDS in water to prevent scaling and nozzle clogging. Air Washer System Comparison Chart Parameter Air Washer (Evaporative / Non-Refrigerated) Air Washer (With Refrigeration – DX/Chiller Based) Cooling Principle Evaporative Cooling (adiabatic) Mechanical Vapor Compression (refrigerant cycle) Compressor/Condenser ❌ Not required ✅ Required Cooling Temperature Limit Limited to Wet Bulb Temp (~18–30°C depending on RH) Can go below Wet Bulb (~10–18°C supply air possible) Dehumidification ❌ Not possible (increases humidity) ✅ Can reduce RH (precise control) Best Suitable Climate Hot & Dry (low RH < 50%) Any climate; ideal for hot & humid areas Relative Humidity Output 70–95% RH 40–60% RH (adjustable) Power Consumption Low (Pump + Fan only) High (Compressor, Condenser Fan, Chiller, Pump) Water Requirement Moderate to High (depends on evaporation) Low to Moderate Temperature Control Precision ❌ Low – Varies with outside RH/DBT ✅ High – Setpoint based control possible Initial Investment Low to Medium High Operation Cost Low (mainly electricity for fan & pump) High (energy-intensive due to refrigeration) Maintenance Simple: scale removal, nozzle check, water quality Complex: includes refrigerant circuit, compressors, coils Application Suitability Textile, Foundry, Paint Booths, General Ventilation Precision HVAC, Pharma, Data Centers, Labs Noise Level Low to Moderate Moderate to High (due to compressor) System Complexity Simple Complex Environmental Impact Eco-friendly (no refrigerant gases) Dependent on refrigerant type (may have GWP impact) References & Sources Standards and Guidelines ASHRAE Handbook – HVAC Systems and Equipment🔗 ASHRAE Handbook Online ISO 16890:2016 – Air Filters for General Ventilation🔗 ISO 16890-1:2016 Standard Overview IS 3315: Air Washer Systems for HVAC (BIS)🔗 IS 3315:1974 on BIS Website EPA – Guide on Evaporative Cooling🔗 EPA: Energy Saver – Evaporative Coolers ASHRAE Journal Archives🔗 ASHRAE Journal – Technical Articles Energy and Buildings Journal – Elsevier🔗 Energy and Buildings – Evaporative Cooling Research Trane – Whitepaper on Evaporative vs Refrigerated Cooling🔗 Trane Commercial HVAC – Resources & Whitepapers Carrier Commercial Systems – Technical Library🔗 Carrier HVAC Technical Resources Johnson Controls – HVAC System Design Guides🔗 Johnson Controls – Resources Industrial Pollution and Environmental Responsibility Wet Scrubbing for Cyanide Fumes Neutralization Comparative Analysis of Industrial Blowers Wet Scrubber Manufacturer Kenya Industrial RO Plant Manufacturer Membrane Bioreactor Waste Water Treatment Gaseous Emissions Control for Sewers and Man Holes Effluent Treatment in Paper Mills Kenya Air Washer Manufacturer Blowers for Refinery Applications Zero Liquid Discharge Plant for Waste Water Treatment Flue Gas Desulfurization System Fumes Extraction System Manufacturer Cartridge Dust Collector Manufacturer Air Stripper Manufacturer South Africa Wet Scrubber Manufacturer Explosive Dust Collector Manufacturer Quench Towers Manufacturer Steam Stripper Manufacturer Oil Mist Collectors Manufacturer Primary Circular Clarifier Lamella Plate Vertical Clarifier Solids Contact Clarifier Parallel Plate Settlers Manufacturer Horizontal Plate Clarifier Manufacturer Industrial Blowers Manufacturer Packed Bed Wet Scrubber Manufacturer Carbon Adsorption Equipment Manufacturer Venturi Scrubber Manufacturer