OPERATION & SERVICE MANUAL FOR NEK-A EVAPORATIVE CONDENSER  

2016

V. 3-2

2016 V.3-2

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Content 1 ‐ Description and Components of Condenser NEK‐A ........................................................................... 2 

2‐ Handling and Unloading ..................................................................................................................... 3 

3 ‐ Positioning and Assembling ............................................................................................................... 4 

4 – Connection of Pipe and Piping .......................................................................................................... 8 

5 ‐ Refrigerant Piping .............................................................................................................................. 9 

6 ‐ Electrical Connections ...................................................................................................................... 10 

7 – Operating Limits .............................................................................................................................. 10 

8 –Water Recirculation ......................................................................................................................... 11 

9 ‐ Inspection and Maintenance ........................................................................................................... 12 

 

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1 - Description and Components of Condenser NEK-A

This manual contains information about installation, commissioning and maintenance of the Evaporative Condenser model NEK-A.

We also recommend to consult other available publications as, for example, Real Decreto RD 865/2003, the Technical Guide for refrigeration towers by IDAE (Instituto para la Diversificación y Ahorro de la Energía), or Eurovent document 9/7-2011.

The condenser NEK is intended for condensing refrigerants for Air Conditioning or Cooling systems. It is suitable to work with following fluids: R134a, R404A, R407C, R507A and R717 (NH3). For other refrigerants (fluids) please contact our Technical Department for advice.

Test pressure for the condensers is 31.5 bar.

 

Figure 1

1. Drift eliminator 2. Heat exchange coil 3. GFRP casing 4. Union between two bodies with seal

joint 5. Access door for maintenance 6. Purge 7. Overflow 8. Drain pipe

9. Water pump 10. Float valve (water makeup) 11. Suction pipe for pump 12. Pump filter (strainer) 13. Pump pressure pipe 14. Fan 15. Liquid outlet (for refrigerant) 16. Gas inlet (for refrigerant) 17. Expansion joint

Figure 1 shows the main components of the NEK-A evaporative condenser. The casing

is made of glass-fiber reinforced polyester (GFRP), which is extremely resistant to corrosion. The heat exchanger coil and the internal frame are made of steel and they are completely hot dip galvanized by immersion after their manufacturing. The fan casing and the protection grids are made of stainless steel. The high efficiency drift eliminator is made of PVC with stainless steel frame.

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2- Handling and Unloading

The condenser will be delivered en (2) sections (Coil & Fan sections). For handling use only the lifting points as indicated, take special care not to damage the polyester casing or the fans.

For lifting the bottom of the condenser (formed by the sump and fans) use lifting beam or lifting device, as per Figure 2. Pass the lifting slings by the interior support structures.

Figure 2

For the upper section (condenser coil) use the lifting eyes as fitted and appropriate lifting beam and slings to have weight in balance, insuring the slings forming the angle of max. 60 degrees as per Figure 3.

Figure 3

ATTENTION!

The assembling of the two parts must be made in final location of the condenser. ATTENTION!

NEVER perform lifting or movement for the condenser assembled in one block. If it will necessary re-locate condenser it must be de-mounted in two parts (sections) again.

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3 - Positioning and Assembling

To choose the site for the correct functioning of condenser you are to keep in mind air circulation and regular inspection and maintenance.

It is recommended to have minimum distance of 1.5 meters between the condenser and surrounding walls. See Figure 4.

Figure 4

ATTENTION! The condenser must be installed at level on a smooth base of concrete or flat metal structure. En later case the structure support must follow the distance between the beams, shown in Figure 5.

(Transverse position as indicated)

Figure 5

ATTENTION!

The structure must be constructed for the total weight of condenser in operation with a basement full of water and refrigerant charge.

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Assembling of condenser to be held as follows:

ATTENTION! The condenser assembly and installation must be performed by qualified personnel and in accordance with applicable security policies.

1. Locate the bottom (fan/sump section) of the final location.

2. Install the upper part (coil section) on the bottom one (fan section), ensuring that the upper part goes down at level to facilitate the engagement of the tabs and the correct alignment of the holes in the polyester casing (use guide rods).

Figure 6

ATTENTION! DO NOT remove the lift of the crane before the final assembling is finished

(Step 2). 3. From inside the sump remove the "porches". Be careful, weight of each “porche” is

22 kg.

Figure 7

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4. Check that the steel frame of the upper part of condenser rests correctly on the steel

structure of the sump, freeing elements provided for anchoring. Align if necessary, together with the perimeter holes in the flanges of polyester casing. See Figure 8.

Figure 8 5. Fit the two parts together by using the clamps as shown on Figure 9 and ensure that

they are correctly positioned and tighten.

Figure 9

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6. Mount again the “porches”. 7. Assemble with screws and bolts around the polyester casing with care, making sure the

press is only necessary for the proper adjustment between the flanges and the rubber seal.

Figure 10

ATTENTION! It is very important to screw slowly and do not over tighten to prevent enlargement or deformation of the holes in the polyester casing.

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4 – Connection of Pipe and Piping

The following elements are supplied together with condenser to install the water circulation pump. See Figure 11.

Figure 11

1) Pump & motor.

2) Basement.

3) Suction pipe pre-fitted with flange, elbow and gaskets.

4) Discharge pipe pre-fitted with flange, elbow and gaskets.

Assemble and connect the above parts as follows: 1. Join the suction pipe to the pump flange with gasket and

screws.

2. Join the suction pipe to the water outlet flange from the sump with gasket and screws.

3. Join the pressure pipe to the pump flange with gasket and screws supplied.

4. Join the other end to the expansion joint, at water inlet flange.

ATTENTION! Align all the elements in order to avoid tensions which can damage the parts. Once aligned pipes and tightened screws, fasten the pump to the basement to prevent undesirable displacements during operation. To connect the makeup water, overflow and drain we recommend to use threaded PVC elements and hoses. ATTENTION! The makeup water inlet is fitted with a float valve, located inside the basement to maintain a minimum water level in the sump. Ensure that there is always proper water supply at this point, with a pressure not exceeding 5 bar.

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5 - Refrigerant Piping

For connection of refrigerant piping the usual practices in this type of facilities should be applied (pipe dimensions, service valves, purge valves, filters, etc.).

The Figure 12 shows some details for information only. It is recommended to install filter/strainers in the refrigerant system to avoid particles and dirt from the tube fabrication and installation, to damage other parts of the system, as expansion valves, compressors, etc.).

Figure 12  

ATTENTION! Protect the polyester with a wet cloth during welding of the piping of refrigerant connections. Fit the gaskets with sealing after welding. See Figure 13.

 

Figure 13

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6 - Electrical Connections

The electrical connection of the fans and pump should be made directly to the terminal box of each motor. The motors are standard, norm motors. The connection mode, depends on the power supply voltage, and it is indicated on the rating plate of the motor. ATTENTION! The electrical installation and connection must be performed by qualified personnel and in accordance with current standards. Installer is responsible to perform the engines’ protection, and to verify that the voltage, frequency and the section of the electrical cables are adequate to motors’ power and in accordance with the regulations and norms. ATTENTION! DO NOT start up fans without the protection guard fitted.

It is recommended to install a power switch for each motor and to place it as close to each fan as you can. ATTENTION! Verify that the direction of rotation of the pump and the fans is correct (indicated by arrows) and that fan blades do not touch the inside of fan ring. The pump should not be operated if the water level in the sump is less than 150 mm.

7 – Operating Limits

Below limit values for safe and good operation of the condenser are indicated. Control periodically that they are not exceeded.

A continuación se indican los valores límites para un correcto funcionamiento del

condensador. Asegurarse, periódicamente, de que no sean sobrepasados.

- Ambient temperature: -20 / +50ºC

- Voltage (V) and power (A): as indicated on the rating plate of the motor.

- Flow of water pump: as indicated on the rating plate of the pump.

- Water temperature: +2 / +50ºC

- Maximum water pressure for makeup: 5 bar

- Temperature of water for makeup: +2 / +30ºC

ATTENTION! Don´t let the water in sump to freeze during stand still of the unit when the outside temperature is below 0°C. Empty water sump and install electrical heater elements.

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8 –Water Recirculation

For the proper functioning of the evaporative condenser it is necessary to have the sump filled up of water to 2 cm below the overflow level. During operation some water evaporates and therefore increases the concentration of impurities and deposits in the sump. Therefore it is necessary to carry out continuous purging of a small portion of the water to prevent excessive concentration of such impurities. Thus, water makeup should ensure sufficient water to compensate both evaporation and purging. Indicatively, the evaporated water is equal to 1.5 liters per kW of heat rejected by the condenser (capacity). To prevent the growth of microorganisms - potentially harmful to the health of the people, it is necessary to install a water treatment system (by a specialized company), since the start-up of the implementation of the installation and, subsequently on regular basis, according to current regulations and norms in the county. ATTENTION! The current legislation (may vary in different countries) require to carry out control and treatment of water in the sump of condenser, from startup and periodically. Using chemical treatment of water, make sure that the products used are compatible with galvanized steel.

Here are some recommended values for the water quality recirculation listed:

pH: ........................................................ between 7.0 and 9.0

pH during initial passivation (*): ............ between 7.0 and 8.2

Total hardness (CaCO3): ...................... between 70 and 500 ppm

Total alkalinity (CaCO3): ...................... 500 ppm, maximum

Total dissolved solids: ........................... 800 ppm, maximum

Chlorides: .............................................. 200 ppm, maximum

Sulphates: ............................................. 200 ppm, maximum

Conductivity: ......................................... 2000 µS/cm

Total salt content: ................................. 3000 ppm, maximum

Iron content: .......................................... 0.5 ppm, maximum

(*) Formation of the protective layer of galvanized steel (passive oxidation) which occurs in the first weeks of operation. During this period, the pH value should be between 7 and 8.2 and total water hardness between 100 and 300 ppm (parts per million = mg / l).

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9 - Inspection and Maintenance

Establish Service & Maintenance programme for regular and planned inspection of unit and maintain log book with all adjustment and repairs carried out. ATTENTION! Make inspection of unit performance the first 24 hours from start-up and after long period of stand still. The inspection and major maintenance tasks are:

1. General inspection of the condenser for any abnormal noise or vibration.

2. Check that nothing is obstructing the air inlets and outlets.

3. Check for no leaks in the water connections or of the refrigerant.

4. Check the water level in the sump during operation and regulate it if necessary.

5. Check the operation of the float valve.

6. Clean the filter (strainer) in pump suction.

7. Empty the water sump and clean it thoroughly.

8. If there are, check the status and operation of the gates of overpressure.

9. Remove the drift eliminator elements and clean them.

10. Check and clean the spray nozzles and the heat exchanger coil.

NOTE: This manual includes the current data at the time of publication, which should be confirmed at the moment of installation. In order to improve the product in question some specifications, weights and dimensions can be changed without notification.

If more information or clarification regarding the installation or maintenance of the condenser is required please contact our technical department.