Kelcroft EMSD Cooling Tower Audit 2335 9830
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Replacing Air Conditioning Chillers



BY John A. Herbert

Cost effective chiller replacement in Hong Kong

Kelcroft helps you replace your old, inefficient air cooled chiller plant with new energy efficient water cooled chiller systems so you can enjoy lower operating costs.

E&M Troubleshooting, air conditioning expert engineer,

Background

Historically, Hong Kong suffered severe shortage of fresh water, therefore the only type of air conditioning equipment and chillers permitted in Hong Kong were air cooled (as pictured above). One of the consequences - more than one third (33%) of all the electricity consumed in Hong Kong was used to power air-conditioning systems [1].  

The HKSAR government realized that alternative systems such as water cooled chillers (using evaporative cooling and cooling towers) would reduce the territories electricity consumption.

A pilot scheme was introduced in year 2000, and subsequently expanded to cover most of the Hong Kong territory, it allowed water cooled chillers for commercial air conditioning purposes to be installed.

chiller replacement energy efficient operation Hong Kong, China, Asia :: Kelcroft


Water Cooled Chillers

Water cooled chillers use less energy used than their air cooled counterparts. Yet, the circulation of chilled water to room equipment, including the fan coil units, or air handling units is the same for both types of chiller. 

The main difference between an air cooled chiller and a water cooled chiller is the method of heat rejection - as the name suggests instead of air being used for cooling water is used.

Water cooled chillers do not have large V coils, and fans found in air cooled chillers, so they are physically much smaller, and don't have heat rejection fans like air cooled chillers to discharge the waste heat, instead they are connected to a device called a cooling tower that provides a wet evaporative process to handle the heat rejection from the chiller to the outside air.

A well maintained cooling tower enables the entire cooling system to perform more reliably and ensures that you get the most from your energy investment.

Water cooled chillers provide building owners with significant benefits over air-cooled systems, including:

  • lower energy costs
  • smaller size
  • lower sound levels

For systems that operate overnight, the a properly designed system has greater efficiency as the outside air wet bulb temperature is lower during the hours of darkness reducing the load on the chiller.


E&M Troubleshooting, air conditioning expert engineer,

Water Cooled Chiller Operation

However, experience indicates that the majority of cooling towers in Hong Kong are installed incorrectly, and are not operating at peak efficiency. The cooling tower itself is only one part of the whole air system, the design of the condenser water system and controls partially dictate the energy efficiency of the air conditioning system.

cooling tower management

Whilst the running cost is lower, with water cooled chillers, their necessary cooling towers require active management, and should not be operated without regular maintenance. 

The operation and maintenance of the cooling tower is vital the chiller performance since in addition to their primary purpose cooling the condenser water, they are efficient air cleaners. 

A large quantity of outdoor air is circulated through the cooling tower and the air is scrubbed cleaning the air, that means the dust and dirt in the air is now deposited into the cooling tower water, this forms mud's and sludge which collect in the cooling tower fill and the basin, these must be property treated and cleaned. 

Because it is an evaporative process the concentration of chemical elements and solids will increase over time, therefore water treatment protocols are needed to monitor and control the water quality.

Legionella Risk

We must not forget that cooling towers are a known source and amplifier for Legionella, the bacteria that causes Legionnaires disease. Proper maintenance measures including adequate water treatment and regular testing must be enforced to mitigate the health and safety risk in accordance with the ordinance.


Consult Kelcroft experts today

For design of safe and energy efficient water based chiller systems and air cooled chiller retrofits call the experts today - our Hong Kong office telephone: +(852) 2335 9830 or send us an email message

1. EMSD end use energy data
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