Energy requirements for the operation of a
chiller account for a significant amount of total energy
requirements. An effective water management program is essential in
controlling energy usage. However, even the very best of water
management programs do not totally eliminate scaling. Minimum levels
of even soft scale accumulation on condenser tubes will greatly
increase the annual energy expense. Today, there is an innovative
solution available that will improve chiller performance by
eliminating scale, translating into substantial energy
Fig. 2 Additional Energy Cost required due to Fouling in Condenser Tubes
Energy consumption is dependent upon the
efficiency of a chiller, hours of operation, average load, cost of
electricity, and the amount of fouling. Figure 1 depicts the
additional cost incurred due to fouling. For example, when the
fouling factor is 0.003 (i.e. scale thickness of 0.036 in.), the
additional energy cost per year for a 500 ton chiller is $25,300.
Energy savings of equivalent amounts can be realized with effective
Fig. 3 Additional Cost Incurred Due to Fouling in Terms of Chiller Size (tons). This data is based upon actual kilowatt per ton data as a function of the fouling factor, and was provided by York International Applied Systems.
Condenser tubes last significantly longer if properly maintained. Once fouling occurs in condenser tubes, scales are removed by using acid, steel brushes and abrasive cutters, which shorten the life of the tubes. Premature replacement of these tubes is expensive. An investment in preventive maintenance such as the ED 2000 system can prevent this additional cost.
Electronic Descaling (ED) 2000 offers an innovative electronic solution to significantly reduce scales in condenser tubes. The source of scaling problems lies in recirculating water whose TDS (total dissolved solids) level is often above 1500 mg/L. Even in a soft water region, the TDS level of the recirculating water is high due to the evaporation of water in the cooling tower. Because of the inverse solubility laws, dissolved mineral ions such as calcium, bicarbonate, etc., precipitate as the water is heated in the condenser tubes, resulting in the deposition of scales on the tube walls. This phenomenon we call "uncontrolled precipitation."
The ED 2000 solution, called "controlled precipitation" causes the dissolved mineral ions to precipitate in the feed pipe of a condenser, thus preventing mineral ions from adhering to the condenser tube walls. Solenoid-induced molecular agitation (SIMA), created by the Faraday's law, forces dissolved mineral ions to precipitate to large insoluble mineral crystals. By this "controlled precipitation" the crystals suspend in the water and do not adhere to the condenser tube walls. The precipitated particles settle at the bottom of the tower sump and are removed through regular blowdowns, resulting in lowering the TDS level of recirculating water and the consumption of water.
The presence of scale in condenser tubes
decreases the efficiency of a chiller, greatly increasing energy
cost. Small amounts of scale, even with effective treatment systems,
may increase cost of operation by 30% or more. By preventing even
small amounts of scale build-up, the ED 2000 Anti-Fouling System
provides enhanced performance and lower energy
Fig. 4 "Controlled precipitation" converts dissolved mineral ions to insoluble crystals, thus preventing the new scale in condenser tubes.
Fig. 5 Annual Electric Cost vs. Month of Operation. Due to the use of ED2000 Anti-Fouling System, significant savings can be achieved.
One can monitor the approach temperature, DT2, defined as the temperature difference between refrigerant outlet and cooling water outlet in condenser.
Without Anti-Fouling Device, chiller performance as measured by the approach temperature, DT2, will decrease with time, requiring ever-increasing energy as the cooling season progresses.
With Anti-Fouling Device, chiller
performance as monitored by the approach temperature, DT2, remains
at the initial fouling-free capacity, and energy requirement is the
same throughout the year as the one in the beginning of the cooling
Effect of Fouling Factor on Electric Energy Consumption