Solutions for Fresh Water-cooled Air Conditioning Systems

• Introduction
  • Mineral Scale
  • Biological Fouling
  • Bacterial Growth
  • Algae Growth
• Benefits
• Case Studies

Water-cooled air conditioning systems are widely adopted when available space and water supply is not a concerned due to its high efficiency over air-cooled air conditioning systems. The high energy efficiency is mainly the result of high heat rejection rate by the evaporation of condensing water so that the loading to the compressor can be lowered.

When most people are enjoying the high energy efficiency of water-cooled system, they are suffering from the problems created by the open condensing water circuit. These problems not only lower the efficiency of system but also impose a health issue to the plant operator and the public.

As water is evaporated from cooling tower, minerals are left behind. Fresh water together with minerals is added to the system. The concentration of minerals as indicated by the Total Dissolved Solid (TDS) or Conductivity is increased and finally deposited on the condenser tubes of chillers and the fills of cooling towers.

The mineral scale impedes the heat transfer between the refrigerant and the condensing water, and gradually degrades the performance of chillers. The heat exchange between the condensing water and air is also affected when the fills are coated with a layer of mineral scale which alters the flow of condensing water

Click here to see how we solve the mineral scale problem.

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Biofilm developed on the condenser tube creates an even higher thermal resistance than mineral scale can do. Traditionally acid is applied to the condenser to dissolve mineral scale before open the condenser cover for brush cleaning. Nowadays acid cleaning is not recommended by some of the users because the condenser tubes can be attacked by acid if the concentration and timing are not properly controlled.

Brush cleaning is therefore simply applied to remove the biofilm for restoring a portion of chiller efficiency. Although the thermal conductivity of mineral scale is much better than that of biofilm, it is still far below than that of the material of condenser tubes.

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Cooling tower not only rejects heat from chiller but also provides an entrance and breeding ground for bacteria. It acts like an air scrubber which traps substances such as dust, suspended particles and bacteria into the condensing water circuit.

Condensing water is conventionally treated by chemicals. However bacterial growth normally cannot be stopped due to design and/or maintenance problems. The growth of bacteria leads to the formation of biofilm and health hazard issue. The high temperature of condensing water especially favours the growth of Legionella which is most concerned by users.

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Historically, algae, along with biofilm formation can be a problem to the cooling tower basin and the fill. These types of growth can have a negative influence on the efficiency of the cooling tower and there is an ongoing concern for guarding against the formation of Legionella bacteria.

To fix the above problem, a total solution should be applied which includes a side stream filtration system with flocculator and a specifically design eductor system. Click here to know more about the flocculator and contact_us to learn more about the eductor system.

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Benefits

HydroFLOW P Range eradicates most of the problems existed in fresh water-cooled air conditioning systems in an innovative, reliable, cost effective and environmental friendly way. The benefits that HydroFLOW P Range can bring to you is numerous and summarised as below:

- Energy Efficiency of Chillers Maximized

Mineral scale and biofilm have a very poor thermal conductivity which reduces system performance and at worst leads to system shut down. The heat transfer coefficent is now brought to its designed value. Thus no more energy is lost due to the tube fouling.

- Equipment Down Time and Maintenance Cost Reduced

The cleaning of tube fouling demands manpower, parts, material and time. The tube cleaning is dramatically reduced.

Moreover the damage of condenser tube by acid cleaning can be reduced. But this is subject to the content of the scaling substance, in area where silica content is high, the acid cleaning may be required to remove the silica scale.

- Health Hazard Reduced

Bacteria killing action is performed when HydroFLOW P Range is on and the condensing water is in motion. This significantly protects the operators, users and the public against the inflection by Legionella.

- Low Power Comsumption

It consumes 15W - 65W (depends on the model used) for its operation. The electricity cost of it is negligible for continuous operation.

- Ease of Installation

It is a non intrusive method and installation can be completed within an hour provided that a single phase power socket is available. There is no change in the pipework and the original equipment.

- Minimal Attention Required

It builts on latest low power solid state technology and its typical power consumption is less than 45W. There is no problem of fatigue, wear out, over-heating and fast aging. It is maintenance free and the only attention to it is to make sure the two LEDs on the control unit are lit up.

- Environmental Friendly

Less chemical is used for tube cleaning. Less water is use for cleaning of cooling tower and less energy is consumed due to the minimized tube fouling by the use of HydroFLOW P Rnage.

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