• Redesigned DWDC C chillers
    Redesigned DWDC C chillers
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Daikin has introduced the new DWDC C series of water cooled chillers with R-1234ze€ refrigerant.

Offering increased capacities and expanded application possibilities, the new chillers are the latest Daikin products to help specifiers and end users stay ahead of rising energy costs.

The new DWDC C series relaunches the consolidated fame of the Daikin centrifugal chiller series in a brand new design.

Available in a wide choice of cooling capacities and component combinations, the range has been developed to optimize energy efficiency and reduce operating costs.

Maximizing performance at both full- and part-loads, the new Dual compressor chillers are available with R-134a or R-513A or R-1234ze, in single refrigerant circuit design.

As part of a building system, centrifugal compressor chillers represent a significant investment. Suitable for new build or retrofit, the new chiller range delivers real benefits for the bottom line.

The dual compressor DWDC C chillers offer many benefits, including outstanding part-load efficiency, and system redundancy similar to two separate chillers, with a lower total installed cost. The DWDC C can be equipped with Variable Speed Drive, for which Daikin has introduced a brand new and enhanced solution with this latest product series.

Daikin DWDC C dual centrifugal compressor chiller range offers a choice of cooling capacity from 2100kW (600RT) up to 9000kW (2500RT) with both R-134a and R-513A & cooling capacity from 1500kW (450RT) up to 6700kW (1900RT) with R-1234ze at nominal AHRI conditions. 

All models are fitted with a single refrigerant circuit.

‘Right-sizing’ chiller selection offers reduced installation costs from the outset: DWDC C series allows virtually infinite combinations of heat exchangers, gears, and semi-hermetic motors to provide the exact required capacity, minimizing the need for a costly step up to a larger-size chiller package.

Daikin DWDC C dual centrifugal compressor chillers have two of everything connected to the evaporator and condenser – two compressors, two lubrication systems, two control systems, and two starters. 

If any component on a compressor system fails, the component can be removed or repaired without shutting down the other compressor; providing an automatic back-up with at least 60 per cent of the chiller design capacity available on DWDC units.

Redundancy is also built into the distributed control system, which consists of a unit controller, a compressor controller for each compressor and an operator interface touch screen.

The chiller will operate normally without the touch screen being functional. If a compressor controller is unavailable, the other compressor will operate normally and handle as much of the load as possible.

 With DWDC C dual compressor chillers, there are two smaller motors (as compared to a single compressor chiller with one larger motor) which produce the same cooling capacity. The microprocessor control logic is built in such a way that when the second compressor is to be started, the first compressor is unloaded further and the second compressor startup is initiated.

This starting method reduces the total inrush current of the dual compressor chillers. Additionally, if an emergency power back-up generator is utilized, this method can reduce the size of the generator. 

 For chillers operating at 60 per cent  and below load for DWDC’s, Daikin has programmed the unit controls to allow only one compressor to run, which results in lower run hours. Lower run hours inherently reduce wear and tear of the compressor and increase its overall life as compared to a single compressor chiller.

These chillers have a single-refrigerant circuit for the evaporator and condenser with two compressors running in parallel and are available in one, two or three-pass configurations. Their salient feature is that at single-compressor, part load operation, the running compressor can utilize the entire chiller’s heat transfer surface, providing outstanding part load performance. 

The flexible control logic of the Daikin inverter drive maps exact performance curves at every condition to minimize speed and still deliver the required cooling capacity. This allows the DWDC C chillers to take advantage of off-design conditions to save energy for comfort cooling applications with variable loads - even for data centres with a constant heavy load. 

The unique design of Daikin’s Inverter uses fewer internal components to create the optimal balance between cost and performance. Engineering and factory-mounting the Inverter provides significant economies of scale, ensuring low in-rush currents to the chillers, reducing the risks of overheating and wiring deterioration over time for a more dependable motor life.

The Inverter is available also in a ‘Low Harmonic -LH’ version (option) in accordance with IEEE-519 2014 requirements (THDi<5%). 

The unique and latest design of the Daikin Inverter Low Harmonic Filter allows to adjust the Harmonic Current according to the specific application to achieve <3% THDi.

New heat exchangers flood type technology have been designed by Daikin in order to improve the heat transfer performance thanks to the most advanced tube type in the market. This innovative design allows to have the top flexibility to create the optimal balance between cost and performance. DWDC C chillers layout has been developed in order to be ready for the Free cooling operation and customizable for Marine application.

Daikin’s precision-engineered gear driven design allows for lighter components, less vibration, and ability to select gear ratios that will provide the optimum impeller speed whatever the application.

Older direct-drive designs must use large, heavy impellers to reach similar tip speeds, which cause more vibration and greater stress on shaft and motor during unexpected electrical interruptions. 

The compact design and lighter weight components enable efficient hydrodynamic bearings to be used (079-126 compressor models). This means that during operation, the shaft is supported on a film of lubricant, with no shaft-to-bearing contact, providing theoretical infinite life bearings under normal circumstances.

The design simplicity of the Daikin centrifugal compressors provides increased durability and reliable performance.

Daikin is a pioneer of the use of moveable discharge geometry to lower the surge point of centrifugal compressors which offers an outstanding unload capacity. The point at which the compressor enters a stall or surge condition generally limits compressor unloading.

Chillers with a fixed discharge will experience stall or surge at low loads due to refrigerant re-entering the impeller. When in a stall condition, the refrigerant gas is unable to enter the volute due to its low velocity and remains stalled in the impeller.

In a surge condition the gas rapidly reverses direction in the impeller causing excessive vibration and heat. Daikin compressors reduce the discharge area as load decreases to maintain gas velocity and greatly reduce the tendency to stall or surge.

The use of R-1234ze(E) offers an environmentally friendly solution, combining a low Global Warming Potential (GWP) with high energy efficiency. R-1234ze(E) is an HFO refrigerant (Hydro Fluoro Olefins). Its Ozone Depletion Potential (ODP) is equal to zero (0) and the GWP is 7 (according to the EU F-gas Regulation*1).

The GWP value is less than 1 according to the IPCC Fifth Assessment Report. 

The introduction of the new R-1234ze(E) range provides a long-term solution that supports the HFC phase down schedule of the F-gas Regulation

Together with R-1234ze(E), Daikin can offer products with conventional refrigerant R-134a or R-513A (which have lower environmental impact than R-134a), according to customer needs.

All above mentioned refrigerant can be used for lifetime chiller operation, eliminating the uncertainty of refrigerant availability. Its Ozone Depletion Potential (ODP) is equal to zero (0) and positive pressure refrigerants.

DWDC C Series chillers are designed and tested with the aim of minimizing the risk of refrigerant leakage into the atmosphere.

Because they operate slightly above atmospheric pressure, outside air containing non-condensable moisture cannot enter the chiller, eliminating the need for a purge unit to evacuate water vapor and refrigerant into the atmosphere.

 

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