coolflex application report_kw per rack

7/28/2019 CoolFlex Application Report_kW Per Rack

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COLD-AISLE CONTAINMENT IN DATA CENTRES

the smart concept for optimal energy use

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Application Report

Cold-Aisle Containment in Data CentresThe smart concept for optimal energy use

Cooling requirements in data centres are continually rising, causing conventional climate control systems to beoverloaded.

Switching to a water cooled systems is an option, but structurally and financially this is not always possible.

Cold-Aisle Containment (CoolFlex) is another option. This option consistently separates cold and warm areaswithout requiring structurally changes to the data centre.

Over several weeks the efficiency of CoolFlex was tested and proved. The test was conducted using fan heaters tosimulate the heat load generated by servers.

The result: At a thermal load of ca. 14kW per rack, the required temperature of 23C in the cold aisle wasreached. During further tests, several computer room air conditioning units (CRAC) were switched off tosimulate an emergency. During these tests the cold aisle temperature of 23C was only marginallyexceeded.


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Description of application:

Test conditionsThe raised floor provided greater energy efficiency by directing cool air through perforated plates in the cold aisleand by sealing the cable entry in to the racks. Knrr isolated the cold and hot zones within the server racks usinginfill panels. All 4 cold aisles were then enclosed using cold aisle containment.

The 342 KW heat capacity was simulated via fan heaters (38 x 9kW = 342 kW). 288 kW heat capacity wassimulated within aisle 2. Aisle 1, 3 and 4 were not in use and therefore produced no heat. The remaining 54 kWwere distributed throughout the room, simulating the heat capacity in the network and free standing racks.

To minimise the loss of circulation and pressure caused by the raised floor, Knrr used special grate catchinstead of perforated raised floor plates. All holes for cables through the floor were sealed to prevent hot airshortcuts.

The CRAC units used were designed to use 250 kW in their energy-efficient, normal mode and 500 kW at highpower mode. The capacity of the fans is proportional to the third power of the circulatory. Therefore it is moreenergy-efficient to run all CRAC units at lower speed, instead of using less CRAC units at their maximal speed. Byconsistently isolating cold and warm air, the nominal capacity of the CRAC units is increased, therefore the samenumber of CRAC units can run at a high power mode, without reducing redundancy.


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Test areas

Test 1: Energy-efficiency in normal mode 6 CRAC units in normal mode (speed ca. 30%) Pressure test with a rising thermal load

Results during full load(ca. 288 kW in aisle + 54 kW) Temperature of cold aisle: 23,0 C Temperature of warm aisle: 37,0 C

Test 2: Emergency (Breakdown of 2 CACUs) 3 CRAC units in emergency mode (speed ca. 80%)

Results during full load(ca. 288 kW in aisle + 54 kW Temperature of cold aisle: 23,1 C Temperature of warm aisle: 42,9 C


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Test 3: Extreme emergency (Breakdown of 4 CACUs) 2 CRAC units in emergency mode (speed 100%)

Results during full load(ca. 288 kW in aisle + 54 kW) Temperature of cold aisle: 23,5 C Temperature of warm aisle: 47,0 C

With only 2 CRAC units the temperature in the cold aisle did not exceed the required 24C.After a time the fan heaters simulating server heat load failed due to a fail safe switch.

Results and Conclusions

To discover the maximum capacity of cold aisle containment by increasing the heat capacity in the data centre.- Load per Rack 3.6kW (Face: 3.5 m = ca. 1000 W/m) = possible!- Load per Rack 7.6kW (Face: 3.5 m = ca. 2000 W/m) = possible!- Load per Rack 10.8kW (Face: 3.5 m = ca. 3000 W/m) = possible!- Load per Rack 14.4kW (Face: 3.5 m = ca. 4000 W/m) = possible!

The cold aisle containment could possibly discharge a higher heat load however the fan heater fail safe thermostatcaused at collapsed after 4'000W/m. Also the test equipment was not calibrated for higher heat load. Thereforewe could not demonstrate the limits of the cold aisle containment.

Note: It is important to note that during this pilot project, fan heaters were used to demonstrate the coolingcapacity. Fan heaters can only simulate the heat generated by servers, as they have a lower flow volume acrossthe server. We are positive, that in a real situation, 10 to 12 KW per rack should be possible (various other expertsdo not differentiate between the use of fan heater and real servers)


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Pictures of test site


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Services providedUsing trained personnel, Knrr is able to provide the following services:Consulting, calculation, and simulation of a solution.Simple installation into existing racks (dependent of make of rack).Integration and installation without the need for down time.

Data Centres Thermal Assessment- Review of thermal demands and air flow within the data centre- Thermal imaging of the computer centre, several aisles and/or racks- Proposal of cost effective measures- Complete report, with achievable improvements

Cold Aisle Containment implementation of the solution- Site visit (inclusive demarcation of project specific items, especially competitor racks)- Creation of project plan

- Detailed pricing offer

Knrr AGMariakirchener Strae 3894424 ArnstorfTelefon +49 (0) 87 23-27-0Telefax +49 (0) 87 23-27-154

E-Mail: [email protected]

coolflex application report_kw per rack

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