Closed Circuit Coolers

ESWA Closed Circuit Cooler

ESWA Closed Circuit Cooler

Induced draft axial fan counterflow closed circuit cooler. The ESWA cooler is used for cooling of water or water/glycol mixtures. The process fluid remains without oxygen and impurities. Executed as per standard with Z-725 (725 g/m² zinc) galvanized steel panels.

The ESWA (ES = low Energy and low Sound) design combines low energy consuming axial fans with high performance counterflow heat exchange. The closed circuit heat-exchange element is located below the air-inlet louvers and completely flooded with the secondary cooled circulation water.

NEW and exclusive on the ESWA is EVAPCO's Sensi-Coil™ which features the maximum amount of Thermal-Pak™ elliptical tubes packed densely togheter in a new coil arrangement. The new Sensi-Coil™ transfers heat through its tube walls in a sensible exchange, no air travels through the tube bundle, therefore tighter tube spacing is possible.

The fillmaterial of the secondary water circulation loop is PVC (polyvinyl chloride) with crossfluted design for optimum heat transfer, strength and stability. The fill is resistant to rot, decay, or biological attack. The fill is able to withstand a water temperature of 55ºC.

The ESWA cooler range is CTI (Cooling Technology Institute) certified in the USA and  is complient with the International Building Code (IBC). Evapco Europe provides with each closed circuit cooler a Thermal Performance Guarantee.

Long-lasting corrosion protection is guaranteed with Z-725 heavy gauge mill hot-dip galvanized steel (Z-725 = 725 g/m² zinc). The galvanized steel construction withstands the most difficult environmental and operating conditions.

For special applications, Evapco can produce the units with stainless steel sump, with a water touched stainless steel construction or a complete stainless steel construction (AISI 304 or 316 are possible).

Technical Data 

  • Unit:    Closed circuit cooler
  • Models:    179 Models (ESWA 72-23H till ESWA 216-46S)
  • Width:    2.388 / 3.607 mm
  • Design:    Induced draft
  • Capacity:    from 320 kW and up
  • Air Flow:    17,8 till 76,2 m³/s
  • Fan:    Axial
  • Drive:   Powerband-belt driven


  • Optimized Technology
  • Lowest energy consumption
  • Low sound emission
  • Easy maintenance
  • Best choice to avoid Legionaires Disease
  • Low risk for recirculation

Optimized Technology

EVAPCO is the first manufacturer to develop a closed circuit cooler with Optimized Technology. The performance of the fill section is optimized with counterflow heat transfer and a flow rate of 6 l/s per square meter. At 6 l/s per square meter, the water flows slowly through the fill layers with maximum time for exposure to the cooling air. After leaving the fill section, the water focuses on the coil at a rate of 12 l/s per square meter...the highest flow over a coil in the industry! At 12 l/s per square meter, the coil is completely flooded with all heat being stripped from the coil by sensible heat transfer. With Optimized Technology providing maximum heat transfer through the fill and across the coil, the ESWA has been designed for low energy enabling customers to benefit from lower operating costs each and every year.

Low energy as standard

The New ESWA again stands apart as being the most energy efficient closed circuit cooler ever. This efficiency, in terms of lower fan horsepower, translates directly to lower operating costs…significantly lower operating costs. With the ESWA installed, customers can realize immediate energy savings which continue each and every year for the life of the equipment. 

  • Replace inefficient units:  
    The potential for energy savings alone is often enough to justify replacing inefficient fluid  coolers with high efficiency models. As an example, a 250 ton centrifugal fan fluid cooler with 44 kW worth of fan motors can be replaced by an ESWA model with a fan motor size of only 11 kW. This tremendous reduction in fan motor size offers annual savings of 10.400 € per year based on 3.500 hours of operation and an electric rate of 0,09 €/kWh.

  • New Product Comparison:
    When comparing the cost of new equipment, energy efficiency and consumption are important factors for determining the total product cost. Units having a lower first cost but higher energy requirements are more expensive to operate and normally end up costing the customer more over the life of the equipment.

Low sound emission

In addition to being the most energy efficient, the ESWA is also the quietest induced draft fluid cooler due to the low fan rotation frequency. The removable access panels around the base of the unit block water noise. At a distance of 1.5m above the fan, the ESW has sound levels that are up to 13dBA less than other standard axial fan fluid coolers of equal capacity. In addition to the standard fans, aluminum LOW SOUND FANS and FRP SUPER LOW SOUND FANS can be installed.

Easy maintenance

The ESWA-design is optimized for easy cleanup and maintenance to all critical locations and components. Easily removable large access doors surround the coil on three sides. When they are removed, the coil and the sump can be cleaned completely from the outside of the unit. Large access doors provide easy access to the eliminators, spray- and drive system.

Best choice to avoid Legionaires Disease

Maintenance is crucial to avoid the proliferation of the LD-bacteria. Avoidance of the penetration of sunlight to the inner part of the cooling tower, no stagnant zones in the sump and cleanable spray systems are of equal importance. The ESWA is equipped with WST (Water and Sight Tight) inlet louvers to avoid the penetration of sunlight into the sump via the inlet louvers. The high performance eliminators (0.001% drift rate) avoid the penetration of sunlight via the fan-opening onto the spray system and fill. The sump is drains completely and the spray system is completely dismountable (including nozzles) and executed with a removable end-cap for easy cleaning.

Low risk for recirculation

Due to the large distance between the high speed air outlet and the multi-sided low speed air inlet, the risk for recirculation is minimized.

The warm process fluid circulates from the heat source to the coil of the closed circuit cooler. The fluid in the coil transfers its heat through the tube walls in a sensible exchange to the spray water that floods over the tubes. Having gained heat from the coil, the spray water then falls to the sump where it is circulated by the spray pump up through distribution piping to the spray nozzles. The warmed spray water is then distributed as a thin film over the fill-pack surface for maximum cooling efficiency.

The fan system operates simultaneously, moving large volumes of air through the unit in a direction opposite the falling water. The air and water contact directly across the fill-pack surface whereupon a small portion of the spray water is evaporated. The evaporation process provides a latent exchange of heat from the spray water to the air passing through the unit. The air is then discharged from the unit as a warm and saturated stream with a final dissipation of heat to the atmosphere. The spray water exits the fill-pack module as a cooled fluid where it floods across the coil in a repeat cycle.

1. Casing and basin design

High Performance drift eliminators 

The drift eliminators remove entrained water droplets from the air stream to limit the drift rate to less than 0.001% of the recirculating water rate. The unit can be located in areas where minimum water carryover is critical. The drift eliminators are constructed of an inert polyvinyl chloride (PVC) plastic material which effectively eliminates corrosion of these vital components. They are assembled in sections to facilitate easy removal for inspection of the water distribution system.

Water Sight Tight air inlet louver (WST) 

The air inlet louvers are both water and sight tight to ensure that the water stays in and sunlight stays out of the cold water basin. The design maximizes thermal performance while minimizing water loss. This sight tight design also inhibits algae growth more effectively than previous designs.

Z-725 Galvanized steel panels 

EVAPCO has developed the ultimate system for corrosion protection in galvanized steel construction - the EVAPCOAT Corrosion Protection System. Z-725 is the heaviest level of galvanizing available for manufacturing evaporative condensers and has a minimum of 165% more zinc protection than competitive designs using Z-275 steel.

2. Heat transfer system

Counterflow fill 

EVAPCO’s patented EVAPAK® fill is specially designed to induce highly turbulent mixing of the air and water for superior heat transfer. The fill sheets are thermally formed into a cross flute design. The individual fill sheets are bonded together to form rigid fill blocks. The fill blocks are then stacked within the unit’s protective casing. The structural strength of the assembled fill pack enables it to be used as a working platform. EVAPCO fill is impervious to rot and decay.

New Sensi-Coil™ Technology

EVAPCO’s new Sensi-Coil™                  ,,, exclusive on the new ESWA closed circuit cooler, features the maximum amount of Thermal-Pak™ elliptical tubes packed denslely together in a new coil arrangement designed with over 20 % more surface area. In addition, all tubes are pitched in the direction of refrigerant flow to give good drainage of liquid refrigerant. The coils are manufactured in accordance with Pressure Equipment Directive “PED” 97/23/EC. High quality steel tubing is used following the most stringent welding and quality control procedures. Each circuit is inspected to assure the material quality and then tested before being assembled into a coil. Finally, the assembled coil is air pressure tested under water at the appropriate pressure, in accordance with the Pressure Equipment Directive. To protect the coil against corrosion, it is placed in a heavy-duty steel frame and the entire assembly is hot dip galvanized at a temperature of approximately 430°C.

3. Mechanical design

Power-Band Drive System 

The AT Cooling Tower features the highly successful, easy maintenance, heavy duty Power Band Drive System. It consists of Standard heavy-duty pillow block bearings with a minimum L10 life of 75,000 hours, extended lube lines, external motor/belt adjustment, aluminum alloy sheaves, solid-back multi-groove Power- Band belts and totally enclosed motors.

Single speed fan motor 

Each Evapco unit is equipped as per standard with a heavy duty, single speed IP55 TEFC / TEAO electrical motor.

Standard axial fan

The standard fans are heavy duty statically balanced axial propeller type. The fans are constructed of extruded aluminum alloy blades, installed in a closely fitted cowl with venturi air inlet for maximum fan efficiency. Each fan blade is individually adjustable. The fan cowl is covered with a heavy gauge hot dip galvanized wire fan guard.

4. Water distribution

Spray nozzles

Large orifice nozzles prevent clogging. Made of non-corrosive, durable ABS plastic.

Spray pump

The spray pump is optimized for high waterflow at relative low pressure. The motor is totally enclosed and protected with an end-cap to ensure a long trouble free operation.

Spray-water distribution system

The water distribution system is enclosed and completely protected by the casing panels and drift eliminators. The water distribution system is made with non-corrosive materials including schedule 40 PVC pipe and durable ABS plastic nozzles. The spray branch piping is easily removed and designed with threaded end-caps for easy cleaning. Evapco’s design avoids the problems of biological growth and clogging.

5. Maintenance and inspection

Large access door

A large hinged access door is located on the side of the unit for easy access to the fan drive system. The belt can be adjusted by tightening the tensioning-bolts on the motor base and the tension can be checked easily through the access door, all while standing at the side of the unit. The bearings can also be lubricated from the side of the unit. The bearing lubrication lines have been extended to the exterior casing and are located by the access door.

6. Operational control

Mechanical water level control

Simple but reliable water level control system with adjustable mechanical float and brass float-valve.