New chillers in the GLAC series enable reduced operating expenses
29. May 2006 GEA design engineers have succeeded in reducing power consumption for partial and full loads
Beginning now, GEA Air Treatment, is offering new chillers in its GLAC series. The new models, which are air-cooled, are intended for outdoor installation, and replace the previous types with rotary screw compressors. The new GLAC series is broken down into 3 lines, with a total of 49 models that cover the rating range from 140 to 1,750 kW.
These units use R134a as refrigerant, which enables operations with outdoor temperatures up to 45°C at the same time, use of R134a is the key to greater energy efficiency. As a result, the new GLAC models operate with several percentage points of greater efficiency than do comparable chillers with R407C. The proven, environmentally benign R134a has no ozone potential, and can be used on a long-term basis as chlorofluorocarbon.
The new series GLAC chillers by GEA are air-cooled, and are designed for outdoor installation. They operate with R134a refrigerant, which contributes to their great energy efficiency. They are characterized by especially high levels of efficiency under partial loads.
Considerably more energy-efficient than models with R407C as refrigerant
Until recently, efficiency at full load was considered the prime criterion for such equipment. Now, however, partial-load behaviour enjoys increasing emphasis, since the full unit output is necessary during only a few hours or days of the year. Current energy calculation methods – such as use of the European Seasonal Energy Efficiency Ratio (ESEER) – are more in line with this approach: which considers to a greater degree load utilization of 25, 50, and 75%, rather than full load, in calculation of the weighted efficiency. GEA design engineers for the new models accordingly granted sufficient attention to analysis of partial-load operations. Their efforts have succeeded, as evidenced by achieving an ESEER classification of approx. 4, and entry in the European energy-efficiency category. This means lower power costs for operators: and, in turn, definite financial benefits, even with consideration of all acquisition and maintenance costs.
The carefully engineered design of the internal unit components – carefully matched to the new refrigerant – is another key factor in assuring greater energy efficiency. GEA engineers especially carefully designed the surfaces of the heat exchanges, the fans, and the compressors. The newly designed condensers, for examples, demonstrate enlarged heat-exchange surfaces. The rotary screw compressors of the new GLAC series have likewise been adapted and optimized for operation with R134a. In comparison to the predecessor components, they throughput greater volume with the same exterior geometry. The rotors and bearing seats are now manufactured with computer-aided precision machine tools, which enable more precise tolerance and optimal function. Bearings that require no maintenance assure long lifecycles of the compressors. GLAC chillers have 1 to 4 compressors, depending on model ratings.
Continuously variable control of compressor output
The new control technology in the GLAC series makes another contribution to energy-efficient operations. It can control each compressor between half and full rated load, with infinitely variable control action. With the larger units with 4 compressors, operations can therefore be continuously variably controlled over the wide range of 12.5 to 100%. The control system offers numerous interfaces that enable interaction with higher-level process-control systems. Another new advance with respect to the earlier GEA chiller models is the fact that all models in the new GLAC series operate with the same controller. This simplifies installation and the interconnection of several units to form a network.
All GLAC chillers are filled at the factory with refrigerator oil and refrigerant. They must pass a trial run before they are delivered to customers. For GLAC model lines 1 and 2, the matching hydraulic modules are available. As options, the chillers are also available in an especially quiet SL version (“SL” stands for “super quiet”).
Optional heat delivery, with output up to 60°C
Upon the customer’s request, chillers can be provided that also output heat. These models feature heat extractors that, depending on the model, remove approx. 20% of the waste heat from the chilled water; this heat can be used to produce hot water at a maximum of 60°C. This option increases cooling output and reduces electric power consumed. The result is additional enhancement of EER efficiency.
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