Daikin Applied enlarges water-cooled centrifugal chiller with low GWP refrigerants range, launching the new DWDC C Series

Consolidating the competitiveness of the new Centrifugal Compressor Water Cooled Chiller, Daikin has introduced in the market the new DWDC C series with R-1234ze(E) refrigerant. Offering increased capacities and expanded applications possibilities, the new chillers are the latest in an array of innovative products developed by Daikin to help specifiers and end users stay one step ahead of EU legislation and rising energy costs.

The new DWDC C series is the next generation water cooled chiller incorporates brand new features in a unique design for every component manufactured by Daikin.

This product relaunches the consolidated fame of the Daikin centrifugal chiller series in a brand new design specifically developed to satisfy the European and Middle East markets.

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.

Flexible choices

Daikin makes several centrifugal chiller types to meet a wide variety of project size and performance requirements, including commercial cooling, district energy plants or manufacturing processes.

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.

The Redundancy Feature

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 percent 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.

Lower Inrush Current

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.

Lower Run Hours

For chillers operating at 60% and below load for DWDC’s, Daikin has programed 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.

Single Circuit DWDC Chillers

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.

State-of-the-art engineering

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 centers 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.

Environmental impact reduction

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.

*1 In the EU F-gas Regulation, the GWP of R1234ze is defined according to the Report of the 2010 Assessment of the Scientific Assessment Panel (SAP) of the Montreal Protocol, Tables 1-11, citing two peer-reviewed scientific references.

*2 Based on IPCC 4th AR. The GWP values of other refrigerants which are not listed in the IPCC 4th AR are obtained from IPCC 5th AR.

*3 Based on ISO 817:2014/AMD 1:2017 and ASHRAE 34-2019

*4 Properties are generated by using NIST REFPROP ver. 10.

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.

Daikin’s Refrigerant Policy

Daikin has a long history of continually reducing the environmental impact of cooling, heating and refrigeration products, as well as having a unique expertise that comes from manufacturing both refrigerants and equipment.

Daikin believes in diversity of refrigerant choice to allow the best suited solution to be used in each application. Refrigerant choice is assisted by the company’s expertise in using fluorinated gases (HFC, HFO) as well as non-fluorinated gases (ammonia, carbon dioxide, hydrocarbons).

For a complete overview, see Daikin’s Policy and Comprehensive Actions on the Environmental Impact of Refrigerants at: Daikin Global Website