Closed Circuit Coolers

MTW Closed Circuit Cooler

MTW Closed Circuit Cooler

EVAPCO focuses on continuous improvement and is committed to develop the most innovative products in the industry. In keeping with this commitment, EVAPCO’s MTW is the first closed circuit cooler in the industry to feature composite fibreglass panels formed entirely by an advanced, environmentally friendly, LRTM closed mould manufacturing process. The MTW is the result of a collaborative effort and the combined resources of EVAPCO’s global entities. The concept and design basis of the MTW stems from EVAPCO Australia’s proven MEC product line, having 20 years of installed history. Beginning with the MEC concept, EVAPCO Inc. then further developed MTW in SolidEdge, a 3D CAD program, then performed standardisation, strength analysis and generated thermal performance at EVAPCO’s premier Research and Development Headquarters in Maryland, USA. 

EVAPCO Composite Sdn Bhd, in Malaysia then brought the design of life taking responsibility for mould design, pattern making, tooling and finally all FRP parts production utilising LRTM manufacturing process. The MTW is unique in the industry having SolidEdge designed patterns, moulds machined by 5-axis CNC, and with parts manufactured using LRTM. All aspect of the MTW, from concept to design to manufacture are performed “in-house” and by EVAPCO. The final assembly of fabricated and globally sourced components is completed at one of EVAPCO’s facilities. Country of original for the final assembled produts is available from Australia, Belgium, Italy or South Africa.

Design Features

The MTW Closed Circuit Cooler is an industry first offering total corrosion resistance with precision moulded LRTM panels. The MTW combines EVAPCO's signature features of easy maintenance, efficient operation and low sound with total corrosion resistance. These features make the MTW the best closed circuit cooler choice in the industry for projects that demand the highest level of corrosion resistance coupled with proven reliability. 

Principle of Operation

The process fluid is recirculated through the coil of the closed circuit cooler. Heat from the process fluid is dissipated through the coil bundle to the water cascading downward over the tubes. Simultaneously, air is drawn in through the air inlet louvers at the base of the cooler and travels upward over the coil in the opposite direction to the water. A small portion of the water is evaporated which removes the heat.

The warm moist air is drawn to the top of the closed circuit cooler by the fan and is discharged to the atmosphere. The remaining water falls to the sump at the bottom of the cooler where it is recirculated by the pump, up through the water distribution system and back down over the coils. 

Efficient Drift Eliminators

The MTW is provided with an efficient drift eliminator system that effectively reduces entrained water droplets from the air discharge to less than 0.001% of the recirculated water flow rate. 

The eliminators are constructed of non-corrosive PVC with a multi-pass design for maximum drift reduction. They are assembled in modular sections for easy removal and access to the water distribution system. 

In addition to reducing drift, the eliminators also function as effective debris screens which protect the spray system and coils from sunlight and debris.

Pressurised Water Distribution System

EVAPCO's Zero Maintenance ZM II® Spray Nozzle remains clog-free while providing even and constant water distribution for reliable, scale-free evaporative cooling under all operating conditions. 

The heavy duty nylon ZM II®  Spray Nozzles have a 32mm diameter opening and a 32 mm splash plate clearance. Furthermore, the fixed position ZM II® Nozzles are mounted on corrosion-free PVC water distribution pipes that have threaded end caps. Together, these elements combine to provide unequal maintenance-free water distribution system. 

Thermal-Pak Coil II®

The EVAPCO Thermal-Pak Coil II® features elliptical tube design, first in the industry and now available with the MTW! The elliptical tube design allows the coil bundle to be densely packed, reducing the number of tubes per bundle up to 10%. This provides weight and cost savings! Additionally, the elliptical tubes have inherent spacing between each other which permits larger amount of air through the cooler without impeding the spray water from falling or creating additional static.

This revolutionary design makes the EVAPCO MTW the leading FRP closed circuit cooler in the industry today! The TPII coils are fashioned out of high quality steel tubing following the most stringent quality control procedures. Each circuit is inspected at the weld seam then tested again before being stacked into a coil. Finally, the coil bundle is pneumatically tested at 2.76 MPa under water to ensure it is leak free.

To protect the coil against corrosion, the coil bundle is placed in a heavy steel frame and dipped in molten zinc (hot-dip galvanised) at a temperature of approximately 427°C.

Note: Closed circuit coolers should only be used on sealed, pressurised systems. Continual aeration of the water in an open system can cause corrosion inside the tube of the cooler leading to premature failure. 

WST Air Inlet Louvers (Water and Sight Tight)

EVAPCO’s WST Inlet Louvers keep water in and sunlight out of induced draft products. The unique non-planar design is made from light-weight framed PVC sections which have no loose hardware, enabling easy unit access. The louver’s air channels are optimised to maintain fluid dynamic and thermodynamic efficiency and block all line-of-sight paths into the basin eliminating splash-out; even when the fans are off. Additionally, algae growth is minimised by blocking all sunlight.

The combination of easy access, no splash-out and minimised algae growth saves the end user money on maintenance hours, water consumption and water treatment costs.

Maintenance Features

Designed for easy maintenance, the MTW Closed Circuit Cooler leads the industry in service friendly features. The two most critical areas for closed circuit cooler maintenance are the basin and the drive system.

The MTW basin section is designed to allow quick and easy access from outside the closed circuit cooler. Just like the basin, all services to the drive system can be safely performed from the side of the cooler. This eliminates the need to stand in the cold water basin or add costly fan deck handrails and safety cages for routine service to the bearings, belts, or electrical equipment. Click on the features below for more details.

Easy Basin Access

The cold water basin section is easily accessible from ground level by simply loosening the two (2) quick release fasteners on the inlet louver assembly surrounding the cooler and lifting out the light weight louver. The basin can be accessed from all four (4) sides of the cooler.

Quick Release Fasteners for Louvers

(standard feature)

The MTW basin is accessible from all four (4) sides (depending on layout) via the air inlet louver. Each louver has two (2) quick release fasteners that remain on the unit when loosened. Lift and remove the light weight louvers for full access to the basin.

Access Panel(s)

EVAPCO's MTW provides one (1) man-sized access door for maintenance as standard. The access panel is designed so that drift eliminators can be easily removed and replaced for cleaning which also provides access to the water distribution system and coils.

Additional access doors may be added subject to approval from the factory, contact your local sales representative for more information.

Drive System Ladder and Platform Package

All units 2.4m and wider can be provided with an Access Ladder & Platform Package.

The platform provides access to the motor and lubrication lines for motor checks and maintenance. Where required, EVAPCO is able to provide safety cages for the ladder. The ladder and platform assembly provided are in accordance with AS 1657.

Drive Systems

The EVAPCO Power-Band Belt Drive is the high performance belt drive system utilised in EVAPCO's closed circuit coolers.  The system is engineered for heavy duty operation and provides trouble-free operation in the most severe of closed circuit cooler applications. The Power-Band Belt Drive System is applicable to 8' wide box sizes and larger.

The fan motor and drive assembly are mounted externally to the unit in a belt drive configuration. Belt tension is checked and adjusted by tightening the J-bolts on the motor base or moving the motor along the all thread. The lubrication lines are extended to the motor base, making bearing lubrication easy. All motor and lubrication lines are safely accessible with the (optional) ladder-platform.

Fan Motors

All MTW units utilise MEPS 2006 standard efficiency motors. Motors are epoxy coated as standard, unless otherwise requested. 

Power-Band Belt Drive

The Power-Band Belt Drive is a solid-back multi-groove belt system that has high lateral rigidity. The belt is designed for closed circuit cooler service, and is constructed of neoprene with polyester cords. The drive belt is sized for 150% of the motor nameplate horsepower ensuring long and trouble free operation.

Drive System Pulleys

Drive System Pulleys located in the warm, moist atmosphere inside the closed circuit cooler are constructed of an aluminium alloy.

Fan Shaft Bearings

The Fan Shaft Bearings on the MTW are specially selected to provide long life, minimising costly downtime. They are rated for a minimum L-10 life of 75,000 hours, making them the heaviest duty flange mount bearing in the industry used for closed circuit coolers.

4' Wide Models Only

The fan motor is mounted internally, in a direct drive configuration. Access to the drive system for maintenance is via the access panel and ladder and platforms are not required. The TEAO fan motor is epoxy coated as standard. 

Five (5) Year Drive Warranty

Evapco provides a standard Five (5) Year Motor and Drive Warranty on all Power-Band Belt Drive and optional gear drive MTW Closed Circuit Coolers. This unique warranty is designed to offer the end user optimum protection against fan drive and motor failure. It is a comprehensive plan which includes the fan, fan shaft, belts, pulleys, fan bearings, gear box, flexible coupling, driveshaft and the motor.

Optional Equipment

The standard design of the EVAPCO MTW provides the customer with the easiest closed circuit cooler to maintain in the industry. There are additional options which can make maintenance easier and extend the life of the closed circuit cooler. These options are listed below:

  • Material options for steel parts available (SS304 and/or SS316)

  • Vibration Switches

  • High Flow Eductors

  • High Temperature Eliminators

  • External Service Platform with Ladder/Cage

  • Low Sound Solutions

  • Special Motors.

Solutions for Sound Sensitive Applications

The MTW Closed Circuit Cooler is now available with three (3) options to reduce the overall sound generated from the ends, sides, or top of the unit. Each option provides various levels of sound reduction and can be used in combination to provide the lowest sound level. Consult EVAPCO's 'evapSelect' equipment selection program for full octave band data sheet. 

NOTE: These low sound options may impact the overall installed dimensions and weight of the unit.

Super Low Sound Fan 9 – 15 dB(A) Reduction!

The Super Low Sound Fan offered by EVAPCO utilises an extremely wide chord blade design available for sound sensitive applications where the lowest sound levels are desired. The fan is two-piece molded heavy duty FRP construction utilising a forward swept blade design. The Super Low Sound Fan is capable of reducing the unit sound pressure levels 9 dB(A) to 15 dB(A), depending on specific unit selection and measurement location compared to the original MTW fan. The Super Low Sound Fan will have no impact on unit thermal performance and is CTI Certified. See Table 1 for low sound height and operating weight additions. Note: Available on 8’, 10’ 11' and 12’ wide models only.

Super Low Sound Fan Height and Weight Additions.

Low Sound Fan* 4 – 7 dB(A) Reduction!

The Low Sound Fan offered by EVAPCO is a wide chord blade design for sound sensitive application where low sound levels are desired. The Low Sound Fan shall utilise a unique soft-connect blade-to-hub design that is compatible with Variable Speed Drives. Since the blades are not rigidly connected to the fan hub, no vertical vibration forces are transmitted to the unit structure which reduces sound pressure levels 4 dB(A) to 7 dB(A), depending on specific unit selection and measurement location. The fans are high efficiency axial propeller type on the MTW product line. 

* The CTI Certified Low Sound Fan will have a thermal performance de-rate up to 3.5%. Consult the factory or evapSelect® program for actual thermal performance.

Water Silencers - Reduces Water Noise in the Cold Water Basin up to 7dB(A)!

EVAPCO’s Water Silencers are located in the cold water basin. The Water Silencers reduces the high frequency noise associated with the falling water and is capable of reducing overall sound levels 4dB(A) to 7dB(A) measured at 1.5m from the side or end of the unit. The water silencers reduce the overall sound level 9dB(A) to 12 dB(A) (depending on water loading and louver height) measured 1.5m from the side or end of the unit when water is circulated with fans off. The Water Silencers are constructed of lightweight PVC sections and can be easily removed for access to the basin area. This option has no impact on unit thermal performance.

Note: Water Silencers are not available on 4’ wide models and models with “No Basin”.