Background

The air conditioning of a government facility is powered by one fresh water cooled chiller and one fresh water cooled heat recovery chiller which produce 260TR cooling capacity in total.

Ordinary chemicals such as biocide, scale and corrosion inhibitor are used in the condensing water. Due to the limitation of chemicals and constraint of treatment program, mineral scale deposit and development of biofilm led to necessity of annual tube cleaning to restore the energy efficiency.

In order to improve the COP of the two chillers, AquaKLEAR is installed. The condenser tubes were inspected and the condition was recorded in picture 1 before switching on the AquaKLEAR. The tubes were then cleaned and anti-corrosion paint was reapplied (Picture 2).

Result

After one year of operation, the condenser cover was dismantled for tube inspection. The condition of condenser tubes and anti-corrosion paint was almost the same (picture 3) as just after cleaning.

The data logged by the existing BMS shows there is a reduction of 20.6% of energy consumption in the chiller plant.

The saving is relatively high because the heat recovery chiller introduced a very inefficiency operation as the hot water is never used which reduces the heat rejection capacity of the chiller. The condition was worsen by the formation of mineral scale and biofilm which are now fixed and therefore a high saving percentage can be realized.

The investment is paid back in 29 months.