Cool Solution Using a combination of innovative technologies the Indigo-thermosyphon provides ultra efficient reliable free-cooling for large Data Centre heat loads at elevated temperatures. Developed, patented and first installed by Star over 25 years ago the proven Thermosyphon chiller technology has been combined with Star’s Indigochiller to form the ultimate high efficiency, reliable, low maintenance free-cool chiller. Over 3,000,000 run hours have been provided without loss of cooling.

The Benefits üü Lower PUE’s üü High Reliability üü Lower Energy Costs üü Leak Free Design üü Free-Cooling without Glycol üü Low Total Cost of Ownership üü Low Carbon Footprint üü Simplicity üü Low Maintenance Costs üü Packaged Solution üü Increased Profitability Taking Advantage of Ambient Temperature

When ambient temperatures fall below the chilled water Annual Thermosyphon Operation Water ON @ 20°C 3No N+1 return temperature, “free-cooling” is available by natural 100 90 80 circulation (thermosyphon) of the , without MECHANICAL 70 running the . In the UK (London) the annual 60 50 mean ambient temperature is just 10.5°C, realising over 40 30 THERMOSYPHON 20

4000 hours of available free-cooling below 10°C. % of Duty from Thermosyphon 10 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Exceptional Annual

Performance of 3No Chillers N+1 1000kW Cooling Load Water ON @ 20°C 120 Performance

Indigo-thermosyphon Chiller 100 Glycol "Free-Cool" Chiller Turbocor Chiller In comparison to other more traditional chiller Screw Chiller solutions for Data Centre cooling applications 80 the Indigo-thermosyphon chiller delivers the 60 highest performance across a range of ambient COSP COSP temperatures. 40 Annualised Coefficient of System Performance

20 (COSP) ranges between 10 to 18 depending on chilled water design temperatures, chiller 0 0 5 10 15 20 25 30 35 configuration and method of heat rejection. Ambient Temperature (°C)

02 Maximising System Performance CHILLER CHILLER CHILLER Due to the importance of cooling to a Data Centre, standby chillers are normally installed for resilience. In a Thermosyphon installation

the standby chiller is utilised when free-cooling is available, 1 2 3 enhancing the annual performance of the system. Simultaneous mechanical and free-cooling operation is available through the series configured chilled water circuit. A full flow bypass valve across each is incorporated to allow continuous system operation during maintenance. Typical Single String Chilled Water Circuit Diagram

Thermosyphon Vs Traditional “Free-Cooling” When ambient temperatures allow, the chillers will switch in sequence to Thermosyphon mode by the simple operation of a 2-port valve in the refrigerant circuit. The transition from mechanical to free- cooling is automatically controlled by the Telstar Supervisor PLC control system.

Thermosyphon Circuit Traditional “free-cool” chillers are connected in parallel to the cooling system and must operate with glycol instead of water with increased pressure drop. Free cooling is achieved by circulating the glycol through an auxiliary finned using a 3-port bypass valve when ambient temperatures are low.

This finned coil located in front the refrigerant condenser creates additional resistance to airflow resulting in the need for higher powered fans and is prone to blockage by build up of dirt and debris. Both result in reduced efficiency when in “free-cool” or mechanical operation. Glycol "Free-cool" Circuit

03 Significantly Lower Running Costs The Indigo-thermosyphon chiller is the ultimate in energy efficient Data Centre cooling. Combining Danfoss’s revolutionary high efficiency oil-free Turbocor centrifugal together with Star’s provenThermosyphon system design, this innovative combination delivers significant energy savings in comparison to traditional “free- cool” solutions.

Danfoss Oil-Free Turbocor Compressor

IT1150 Indigo-thermosyphon chiller

Operating on refrigerant R134a, the chiller design also benefits from a flooded evaporator for improved full and part load efficiencies. Furthermore, EC condenser technology delivers significant energy savings at lower loads. All heat exchanger surface areas are optimised to enhance performance in both mechanical and free-cool operation.

Simple but Efficient Control The Telstar Supervisor is a PLC based overall plant controller that is connected to each of the chillers via Ethernet. The Supervisor monitors the operation of each chiller in addition to the ambient temperature and the common chilled water flow temperature. It uses this information to optimise the chiller operation between mechanical and free-cool modes to always achieve maximum system efficiency. A full colour touch screen HMI displays plant operating conditions, set points, graphs/trends and alarms. A feature of the Supervisor PLC is the instantaneous Coefficient of System Performance (COSP) display. The Supervisor PLC can be connected to the customers Building Management System (BMS) via a MODBUS interface.

Star Telstar Supervisor PLC

04 Delivering Year on Year All Indigo-thermosyphon chiller components have been carefully selected to minimise/eliminate the risk of refrigerant leakage, optimise performance, reduce maintenance costs and enhance the chiller operating life. The result is a chiller that delivers low life-cycle costs throughout a plant life in excess of 20 years. Major financial and government institutions have invested in Star’s Thermosyphon chiller systems to provide efficient and reliable cooling in their data centres.

Star IT550 Glycol Free-Cool Star IA500S Chiller Type Screw Chiller Indigo-thermosyphon Chiller Indigochiller Duty (kW) 1000 1000 1000 1000 No. of Chillers 3 (N+1) 3 (N+1) 3 (N+1) 3 (N+1) Capacity Each Chiller (kW) 550 570 500 500 Expected Chiller Operating Life 20 years 12 years 20 years 12 years Capital Cost of Chillers (%) 100% 94% 91% 64% Average Annual COSP 14 11 7.6 5.4 Water Temperatures (°C) 20/14 20/14 20/14 20/14 10 Year Cost of Energy (%) 100 122 146 162 10 Year Cost of Maintenance (%) 100 145 100 145 Total Cost of Ownership (%) 100 118 133 147

Life Cycle Comparison Table

Indigo-thermosyphon Chiller Design Options Individual Indigo-thermosyphon chiller capacities range from 550kW to 1500kW. Chillers up to 750kW in capacity benefit from being fully factory assembled, commissioned and tested prior to delivery. Chillers above 750kW capacity have remote condensers and require site installation works prior to commissioning and testing. These higher capacity chillers can either be supplied in a weatherproof housing or ideally be located in a purpose built plantroom. IT1500 with Weatherproof Housing

05 All capacities can be offered with either air-cooled or evaporative-cooled condensers depending on requirements. The wet cooling systems are best suited to larger capacity chillers and offer the largest energy saving potential. However air-cooled units have very low operating costs as they require less maintenance. In addition to the standard range of chillers we offer bespoke designed solutions on request.

Indigo-thermosyphon Chiller System Design Multiple Indigo-thermosyphon chiller installations up to a maximum of four chillers can range from 1MW up to 6MW in capacity on a single cooling string. A dual string installation of up to 8 chillers (4 + 4) could deliver an installed cooling capacity of 12MW.

Indigo-thermosyphon chillers are available in a number of chilled water design temperature options ranging from water off at +10°C up to water off at +22°C depending on specific requirements. In order to maximise the efficiency of the chilled water system the highest possible design chilled water condition should be selected. Technical Support Remote Monitoring Hub Our technical, design and manufacturing centre in Our unique remote monitoring hub offers a centralised Glasgow is available to support the local Star branch facility for fault monitoring and plant performance and international service partners with innovative monitoring, reducing the need for unnecessary site solutions to any technical design challenge. visits.

06 Technical Schedule

Model & Rating IT550 / 550kW IT750 / 750kW IT1150 / 1150kW IT1500 / 1500kW

String 2 + 1 3 + 1 2 + 1 3 + 1 2 + 1 3 + 1 2 + 1 3 + 1 Total String Capacity 1100 1650 1500 2250 2300 3450 3000 4500 (kW) Ambient Temp (°C) 35 35 35 35 Dimensions (m) 8.3 x 2.9 x 3.5 9.2 x 2.9 x 3.5 6.0 x 2.4 x 2.4 6.0 x 2.7 x 2.4 GENERAL (L x W x H) each unit* Max Full Load Current 328 497 746 994 (A) per unit

Qty per unit 2 2 3 4

Nominal compressor 275 375 367 375

CENTRIFUGAL capacity (kW) each COMPRESSORS

Dimensions (m) 8.3 x 2.9 x 1.3 9.2 x 2.9 x 1.3 integral integral (L x W x H) each unit* x2 units x2 units No of Fans (each) 12 16 12 16 CONDENSER AIR-COOLED Air Flow (m³/s) per 66 87 66 87 condenser Water Temp In/Out 16 / 10 16 / 10 16 / 10 16 / 10 (°C) per String Water Flow (m³/h) 158 236 216 324 331 497 432 648 EVAPORATOR SHELL & TUBE Water Pipe Size 150NB 200NB 200NB 250NB 250NB 300NB 300NB 350NB

2+1 = String of Two Chillers Duty + 1 Chiller as Standby 3+1 = String of Three Chillers Duty + 1 Chiller as Standby * Dimensions of package include the condenser for IT550 & IT750 models ** As we continually strive to improve our product range, the information within this table is subject to change.

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