Stepless capacity control on screw chillers
Daikin Europe NV (13/07/2005)
New development in the Daikin screw chillers for industrial applications: the upgrade of the entire screw range to stepless compressors.
Following recent new development announcements, Daikin Europe N.V. enjoyed a record order intake for Chillers in May. The next stage in the development programme is the upgrade of the entire screw range to stepless compressors, which is due in August.
With its emphasis on energy efficiency and part load performance, the replacement of stepped control with stepless capacity control provides many overall advantages. Coincident with this important change, updating the air cooled R-134a range completes the standardisation of the control platform to pCO² for the entire screw range.
The Daikin developed G-type stepless single screw compressor enables capacity requirements to be closely matched by modulating the sliding valve position according to the chilled water control condition. Main advantages of continuous modulation are better part load efficiency and more stable chilled water temperatures with closer control tolerance.
Capacity control is infinitely variable between 30% and 100% on single circuit units and between 15% and 100% on dual circuit units. Due to the thermal capacity of the water loop the accuracy of control is maintained for the small percentage of operating hours outside the modulating band.
The pCO² control brings added benefits through the intelligent Daikin control algorithm by optimising the efficiency of the unit at part load conditions. Significant examples are floating set point according to ambient temperature, load shedding through capacity setback, scheduled time groups and comprehensive control logic for independent free cooling. With DICN (Daikin Integrated Chiller Network) supplied as standard, the company is well positioned to drive the market with the provision of cost effective control strategies for multiple chiller installations.
Further modifications include the introduction of standard Polyacryl pre coated condenser fins, thereby improving corrosion resistance. This move is in line with other product ranges and the company’s quality and environmental policies. Furthermore, in order to enhance installation and system reliability, all units will now be supplied complete with flow switch, together with a 1mm mesh water filter on those units with brazed plate heat exchangers.
Last but not least, in order to meet the requirements of the heating market more fully, the leaving water temperature range of water cooled R-134a chillers has been raised (in heating mode) by an additional 10°C to 60°C.
This development together with future planned projects affirms Daikin’s commitment to further develop their Applied Systems business.
Air Cooled:
EWAD-MBY (120-340 kW) Cooling OnlyEWAP-MBY (110-540 kW) Cooling Only
Remote Condenser:EWLD-MBY (120-540 kW) Cooling Only
Water Cooled:EWWD-MBY (120-540 kW) Cooling only / Heating Only
