Chiller Efficiency

Chiller Efficiency - Scalewatcher™ ENiGMA Cracks the Code

Engineers in hard water areas know the problems caused by scale in water systems: increased maintenance, unplanned shutdowns, premature replacement of equipment and higher energy costs. However, few know the full extent of the problem.

Despite maintaining a good water treatment regime, thin layers of scale can form in a chiller’s tubes, increasing the thermal resistance of the heat exchanger and subsequently dramatically increasing the energy costs. The thermal conductivity of calcium carbonate is 4,000 times smaller than that of copper and therefore even the thinnest coating acts as an effective heat insulator.

Chemical Descaling of Chiller tubes a thing of the past?

The knock-on effect of this is to increase the head pressure, resulting in a significant increase in energy consumption of the compressor. According to York International, just 0.04inch (40 thou) fouling the heat exchanger of a 500 Ton Chiller results in £25,000 extra on the electricity bill. The larger the chiller, the higher the energy wasted: the same 40thou in a 1200 Ton could add £60,000 to the electricity bill!

Fareham based Environmental Treatment Concepts (ETC), with more than 15 years experience in Electronic Water Conditioning, has begun to bring this unnecessary waste to the attention of some of their existing customers, including AWE Aldermaston and Mars Confectionery. However, their expertise is limited to successfully applying physical water treatment and a union between ETC and a chemical water treatment specialist would enable them to work together and to offer their customers a complete service solution.

Despite mechanical cleaning a thin layer of scale still coats chiller tubes

Following extensive work carried out in the USA by an associate company, Electronic Descaling 2000 (ED2000), the massive savings to be made by adopting Electronic Water Conditioning are not too difficult to identify. The company insists that no changes to the chemical treatment program are necessary, in fact there is clear evidence that the two technologies complement each other. Certainly, treated water systems are much cleaner and allow safe increases in cooling water concentration factor, resulting in water savings, which alone give a quick return on investment.

One of ETC’s most supportive customers, Reading based McKay Securities PLC, develops and manages property throughout the country and has been using the Scalewatcher™ ENiGMA Electronic DeScaler for years on hot water systems. One of its properties, Mallard Court, Staines, was experiencing problems with its cooling system and the plant was having difficulty with peak demands during summer months.

Unfortunately there was no room to install a larger chiller and therefore they had to accept that on days of high humidity, when cooling towers become less effective, the compressors were liable to trip off on high head pressure – stopping the air conditioning just when the need was greatest.

Mick Flannagan of Metro Heating, the company responsible for maintaining the plant, was very sceptical: "I have seen various electronic scale reducers around and have never seen one that worked". However, he is now one of the thousands of people convinced by ETC. Within weeks of the Scalewatcher™ ENiGMA Electronic DeScaler being installed on the cooling loop, the head pressure dropped by a massive 20psi. As there is only a 50psi difference between low and full load, this has had a major impact on the operational effectiveness of the chiller.

The plant can again cope with all the demands of the changing UK weather and compressors tripping out are a thing of the past. As well as obvious energy savings, the condition of the tower is immeasurably improved, heavy scale deposits have been dissolved and removed by the electronic water conditioner and tube cleaning has been rendered unnecessary. In fact, according to Mick Flannagan, "The Scalewatcher™ ENiGMA keeps the tubes maintenance free and cleaner now than they previously were, even after mechanical cleaning."

From the early work that ETC has carried out on this application, it is obvious that there are thousands of chillers running in the UK wasting millions of pounds in energy. The Building Services Research and Information Association (BSRIA) has calculated that, in the UK, refrigeration associated with air conditioning accounts for some four million tonnes of CO2 production per year. Much of this will be as a result of inefficient chillers.

Despite good water treatment, chillers will almost certainly always have a thin coating of scale in their tubes. From ETC’s observations, a mechanically cleaned system about to be put back into operation, often has a calcium layer approximately 15thou thick. Should an electronic descaler be employed, this layer would simply be dissolved and removed by the water, saving the user thousands in energy costs.

Companies wishing to try electronic water conditioning, which enhances existing water treatments, will be pleased to know that systems are available for rental. Brent Cross Shopping centre in North London is one such client of ETC who prefers this method of enjoying the benefits without having to use capital budget resources. This obviously also satisfies the sceptic; the effectiveness can be evaluated before committing hard earned profits to what may seem a mysterious technology to many.

For ETC there is no mystery. Vast experience of serving industry since 1989 has enabled us to master the technology and to understand just what is going on. ETC was the first company in the world to demonstrate a change in water treated with a physical device. Eight years of research carried out at Drexel University in Philadelphia has also benefitted the company. This ongoing research program promises to result in a fuller understanding of the mechanics of fouling and the most effective methods of removing it. ETC was responsible for introducing electronic descaling into the UK in 1989 and intends to remain in the forefront of the development of this very exciting technology.