Data centar cooling using multiple chiller system with r134a

Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning

ANNUAL MEETING OF THE

Belgrade, May 10, 2011 Slobodan PejkovićMultiple Chiller System with Oil-Free Variable-Spee d Turbo Compressors

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ANNUAL MEETING OF THEREGIONAL OZONE NETWORKFOR EUROPE & CENTRAL ASIA

BELGRADE, SERBIA, 10 -13 MAY 2011

Highly Efficient Data Centar Cooling Using Multiple Chiller System with Oil-Free Variable-Speed Turbo Compressors

Dipl.-Ing. Slobodan Pejkovi ć

Filter Frigo - Serbia


Filter Frigo - [email protected]


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Oil-free twin-turbo centrifugal compressor uses electromagnetic bearings and turbine variable-speed for significant increase of


significant increase of energy efficiency at partial load compared to conventional oil-lubricated centrifugal or screw compressors.


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• Each of the three water chillers installed inTelecommunication Data Centar 'Belgrade ' in April2008 has two turbo compressors and total coolingcapacity of 1.97 MW.

• It has been estimated that in the 2008 cooling seasonthis solution achieved more than 35% energy savingsthis solution achieved more than 35% energy savingscomparing to the previous solution with conventionalcentrifugal compressors.

• We will see the results of preliminary measurement ofthe working characteristics of chillers and EER-energyefficiency ratio for real working conditions.


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Telecommunication Data Centar 'Belgrade '


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In the Telecommunication Data Centar 'Belgrade ',back in 1973, water chillers ware installed with theconventional oil lubricated turbo compressor. The waterchillers used R 12 as a refrigerant.


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The old water chillers



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New water chillers withTurbocor compressors


The advantages of new water chillersover the conventional ones are: • High energy efficiency, especially during reduced part-load, by use of

the oil-free compressors with the variable-speed turbine and flooded evaporator,

• Environmentally friendly refrigerant (R134a),• More efficient heat exchange in the evaporator and condenser (with

no oil film causing additional heat resistances), no oil film causing additional heat resistances), • Higher evaporation temperatures, and therefore higher cooling

capacity at the same temperatures of the water in the evaporator, • Silent work and reduced vibrations, • Low starting current (2 to 5 A ), • Light compressor weight (up to 140 kg), • Precise temperature regulation thanks to software controlling the

compressor.


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Compressor


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Evaporator

CondenserPrincipal

operatingscheme for

water chiller


Why R134a as a refrigerant?• ODP=0; GWP=1430• Compressor, semihermetic design, is optimized for use

with R134a, an environmentally friendly alternative to traditional refrigerants,

• Many traditional fluids have become banned and the • Many traditional fluids have become banned and the industry standard R134a might face the same faith in some European countries because of its relatively highglobal warming potential,

• In selection of the working fluid the safety factors often play a dominant role.


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Saturation pressure (abs)vs temperature


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Changes in compressor cooling capacity(from 10% to 100%) is executed in two ways:


� By changing the speed of the impellerfrom 20.000 to 48.000 min¯¹- manufacturers data;from 22.500 to 34.000 min¯¹- our measurements.

� By changing the

.


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opening degreeof the inlet guidevane – IGV.

Impeller

IGV

It was found that combined regulation has a good performance .


FACILITY REQUIREMENT FOR COOLING

• For cooling of equipment and air-conditioning in thebuilding of Telecommunication Data Centar 'Belgrade ',a total cooling capacity is needed of 1.2 MW. For thoserequirements, three water chillers, with water cooledcondensers were selected, each with cooling capacitycondensers were selected, each with cooling capacityof 658 kW, in the following work regimes:

• Water temperature at the evaporator inlet14ºC

• Water temperature at the evaporator outlet 9ºC


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• Water temperature at the condenser inlet29ºC

• Water temperature at the condenser outlet34ºC

• The installed capacity is much higher (1.97 MW) thanneeded, due to the reason of redundancy safeguards.needed, due to the reason of redundancy safeguards.Processor (Manager 3000), controls the work of allthree water chillers. The simultaneous work of all threewater chillers was enabled at reduced load, when theelectric power consumption has been significantlydecreased.


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Processor for controlling the work of three water chillers


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Water Chiller TECS-HF 2AS

ESEER = 0.03 • EER100% + 0.33 • EER75% + 0.4 • EER50% + 0.23 • EER25%


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Water Chiller TECS-HF 2AS

Load % 100 66 50 33

Cooling capacity kW 657.4 433.88 328.7 216.94

Total absorbed power kW 128.4 57.5 34.2 20.7

EER Wh/Wh 5.11 7.55 9.61 10.47

Water entering the evaporator °C 14 12.3 11.5 10.6

Water exiting the evaporator °C 9 9 9 9

Water flow through the evaporator m3/h 113.2

Water entering the condenser °C 29.5 26 22 18

Water exiting the condenser °C 34 28.8 24.1 19.4

Water flow through the condenser m3/h 149.7

Calculated operating parameters of the water chiller


• When two water chillers operate at high external temperatures, in order to satisfy thecooling requirement their total cooling capacity is 2 x 612.6 = 1225.2 kW, while theabsorbed power is 2 x 139.8 = 279.6 kW. The cooling capacity is less than nominal,and the absorbed power is higher. The condensing temperature is tk = 40ºC.

• When all three water chillers operate at decreased speed in order to satisfy the samecooling requirement, their total cooling capacity is 3 x 407.5 = 1222.5 kW , while theabsorbed power is 3 x 64.0 = 192.0 kW, that is 31% less. The condensingtemperature is tk = 32ºC.

• The use of Multiple Chiller System allows unusual redundancy safeguards.


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50%

50%

50%

50%

0%

20%

40%

60%

80%

100%

Cooling capacity Absorbed power

Water Chiller I Water Chiller II

33.3%

33.3%

33.3%

23%

23%

23%

31%

0%

20%

40%

60%

80%

100%

Cooling capacity Absorbed power

Water Chiller I Water Chiller II

Water Chiller III Energy savings


Determination the annual seasonal energy consumptio nChiller operates only 240 days a year, 14 hours per day.

� The first case: work of an old Westinghouse water chiller, with cooling capacity of 1.2 MW. The calculated seasonal electric power consumption is 571,2 MWhduring the year.

� The second case: parallel work of two new water chillers with Turbocorcompressors.During that, the third water chiller serves as a reserve.The calculated seasonal energy consumption is 364,8 MWh,which is 36% less than in the first case.

� The third case: parallel operation of all three new water chillers. The calculated seasonal energy consumption was 212,6 MWh, which is 63% less than in the first case.

� Annual savings in this operating regime of the water chillers would be $37.650.

� The current project indicates a simple payback for the third water chiller of approximately 2.5 years.


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FACTORY MEASUREMENT OF WATER CHILLER’S WORKING PARAMETERS

April 3rd, 2008 test cabin no. 3 test cabin no. 3


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Test cabin no. 3



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Original factory testing report of the water chiller TECS-HF 2AS


MEASUREMENT OF CHILLER WORKING PARAMETERS IN THE FACILITY

August and on October 14th, 2008


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For basic measurement of the water flow rate orifice meter havebeen used in conection with OVENTROP flow-meter OV-DMC 2


For electrical network characteristics measurement,


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For control measurement of water flow rate, the ultrasonic flow-meter UFM 610P has been used, product of KROHNE

For electrical network characteristics measurement,instrument CHAUVIN ARNOUX C.A 8334 has been used


The measurements show that by decreasing the speed of the turbine,power factor - cosφ also decreases, and it increases the percentageof reactive power in apparent power.


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Results of the electrical parameters measuring(power, cosφ, voltage, current intensity)


For indirect measurements of the speed of turbine, openingdegree of inlet guide vane - IGV and for determining therequested load of the water chiller, a computer has been usedwith the software package from »Danfoss TurbocorMonitoring Tool Version 2.1.0.80 «.


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Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioningWater Chiller: TECS-HF 2SΦo=658 kW ; Pw=130 kW ; tw=14/9°C

Compressors: TT300 (R134a)

Date:12/08/2008.

Outside Air Temperature 37.9ºC

Parameters

Discharge Pressure [kPag] 702

Condensing Temperature [°C] 32

Discharge Temperature [°C] 38.5

Water Flow (Condenser) [m3/h] 126.3

Water Temp. (Cond. Inlet) [°C] 25.7

Water Temp. Difference-Cond. [K] 3.1

Heating Capacity [kW] 455.3

Suction Pressure [kPag] 290

Suction Temperature [°C] 7.6


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Suction Temperature [°C] 7.6

Water Flow (Evaporator) [m3/h] 129.8

Water Temp. (Evap. Outlet) [°C] 9.0

Water Temp. Difference-Evap. [K] 2.7

Cooling Capacity [kW] 407.5

Shaft Speed [min-1] 27371

Compressor load [%] 34

IGV (Inlet Guide Vane) open [%] 110

Power Input [kW] 64.0

Cosφ - 0.893

EER - 6.4

Results of measuring the working parameters of water chiller no.2

Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioningWater Chiller: TECS-HF 2SΦo=658 kW ; Pw=130 kW ; tw=14/9°C

Compressors: TT300 (R134a)

Date:14/10/2008.

Outside Temp.21°C

Parameters / Time 12:48 13:08 13:16 14:15 14:34 15:32 15:37

Discharge Pressure [kPag] 887 793 769 702 618 613 595

Condensing Temperature [°C] 40 36 35 32 28 27 26

Discharge Temperature [°C] 50.5 47.4 41.2 36.2 33.8 32.8 32.0

Water Flow (Condenser) [m3/h] 126.1 125.8 125.6 125.6 125.9 125.8 126.3

Water Temp. (Cond. Inlet) [°C] 26.6 25.2 25.4 24.3 24.0 23.5 23.1

Water Temp. Difference-Cond.

[K] 5.0 4.7 3.7 2.6 1.8 1.5 1.4

Heating Capacity [kW] 733.1 687.5 540.4 379.7 263.5 219.4 205.6

Suction Pressure [kPag] 3.0 2.67 2.8 2.89 2.92 2.95 2.98

Suction Temperature [°C] 9.2 5.9 7.0 7.6 8.2 9.1 9.2

Water Flow (Evaporator) [m3/h] 128.5 129.8 129.5 129.8 129.1 128.8 129.4


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Water Flow (Evaporator) [m /h] 128.5 129.8 129.5 129.8 129.1 128.8 129.4

Water Temp. (Evap. Outlet) [°C] 11.3 8.7 8.7 8.9 8.8 8.8 8.9

Water Temp. Difference-Evap.

[K] 4.1 3.9 3.2 2.2 1.6 1.4 1.3

Cooling Capacity [kW] 612.6 588.6 481.9 332.0 240.2 210.0 195.6

Shaft Speed [min-1] 338023397

829182 25434 23784 22907 22520

Compressor load [%] 90 74.8 42.8 26.8 10 10 11.7

IGV (Inlet Guide Vane) open [%] 110 110 110 110 23.6 8.8 8.8

Power Input [kW] 139.8 130.8 78.5 46.5 30.8 23.2 21.6

Reactive power [kVAR] 60.6 56.9 36.6 26.6 21.3 19.2 18.2

Cosφ - 0.917 0.916 0.906 0.867 0.822 0.771 0.762

EER - 4.4 4.5 6.1 7.1 7.8 9.0 9.1

Results of measuring the working parameters of water chiller no.2


During the measurement opening degree of inlet guidevane – IGV was changing from 110 to 8.8%, as well asthe compressor impeller’s speed from 33978 to 22520min-1. The efficiency level - EER changed from 4.4 atmaximum load to 9.1 at reduced capacity of 34% of themaximum load to 9.1 at reduced capacity of 34% of themaximum load. By further decrease of load, theefficiency level - EER would also increase.


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� Oil-free twin-turbo centrifugal compressor uses electromagnetic bearingsand a variable-speed turbine for significant increase of energy efficiency atpartial load compared to the previous solution with conventional centrifugalcompressor.

� Water chillers with water cooled condenser offer high energy efficiency level- EER at the highest external temperatures, because the water chillersoperate with condensing temperature up to 40ºC.

� Part load energy efficiency is outstanding, with energy savings greater than

CONCLUSION

� Part load energy efficiency is outstanding, with energy savings greater than35% compared to the conventional oil-lubricated centrifugal or screwcompressors.

� Totally oil-free operation has improved the heat transfer efficiency.� Extended equipment life was provided with minimal scheduled

maintenance.� The current project indicates a simple payback for the third water chiller of

approximately 2.5 years.� The Multiple Chiller System allows unusual redundancy safeguards with

energy savings greater than 35%.


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Thank You For Your Attention


Question?Question?


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Technology

Data centar cooling using multiple chiller system with r134a