CRAC and AHU: Energy saving in the Synergy of High Efficiency Technologies

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Information about CRAC and AHU: Energy saving in the Synergy of High Efficiency Technologies

Published on September 9, 2016

Author: CAREL_group

Source: slideshare.net

1. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" "CRAC and AHU: Energy saving in the Synergy of High Efficiency Technologies" Enrico Boscaro Carel Industries S.p.A 02/09/2014

2. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" TOPICS 1. CRAC vs AHU: traditional vs innovative? 2. CRACs and AHU for direct free cooling 3. Humidity Control 4. CRACs and AHU for indirect free cooling " CRAC and AHU: Energy saving in the Synergy of High Efficiency Technologies "

3. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" TOPICS 1. CRAC vs AHU: traditional vs innovative? 2. CRACs and AHU for direct free cooling 3. Humidity Control 4. CRACs and AHU for indirect free cooling " CRAC and AHU: Energy saving in the Synergy of High Efficiency Technologies "

4. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" CRACs vs AHUs Traditional VS Innovative?

5. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" CRAC Typical features » Industrialized product » Small-medium air flow » DX or CW » Mounted on the perimeter, in a corridor or even in the white space » Recirculation using access floor or suspended ceiling » Vertical airflow in the unit to save space » Typical cooling system for traditional design datacenters

6. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" AHU Typical features » Custom product » Large air volumes » Mounted on the roof » Recirculation, mix and fresh air introduction by means of air ducts » Suitable for DEC and IEC » Horizontal airflow in the unit » Very popular for new design datacenters » Sometimes there is no Unit but the ventilation is included in the building

7. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" TOPICS 1. CRAC vs AHU: traditional vs innovative? 2. CRACs and AHU for direct free-cooling 3. Humidity Control 4. CRACs and AHU for indirect free-cooling " CRAC and AHU: Energy saving in the Synergy of High Efficiency Technologies "

8. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" A typical installation of a legacy datacenter: room temperature control CRAC installation example (0) Return air from data hall 25°C 40% r.h. Supply air from CRAC 17°C 62 % r.h. Supply air from CRAC with humidifier 17,1°C 66% r.h. Mix in the access floor 17,05°C 64% r.h. Return air CRAC Supply air in the access floor racks » Data hall without containment, downflow CRAC units in the corridor » 18 units with 25000 m3/h airflow: total airflow 450000 m3/h » Total Cooling Load 1,17 MW: S/T ratio 0,88. 365/24/7 operation Control on the return with set @ 25°C 40%r.h. » 9 x 15 kg/h humidifiers for humidity control 17°F 64%rH 25°C 40%rH

9. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" CRAC with AHU as direct Economizer (1) A possible installation with the same design temperatures: full air flow » Use of air handler for direct free cooling as an economizer: air flow equal to the total air flow » Room distribution or use of plenum on return of CRAC units that control underfloor pressure » Economizer mode when fresh air is lower than normal supply set of CRAC: possible air flow control on room temperature » CRACs can be in Standby mode and sensing temperature only for backup cooling » Adiabatic humidifier and Direct Evaporative Cooling to reduce temperature Room air Exhaust air Fresh air Supply air 17°F 65%rH 25°C 40%rH DEC - Adiabatic humidification

10. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" CRAC with AHU as direct Economizer (2) A possible installation for partial free cooling: half air flow » Use of air handler for direct free-cooling as an economizer: air flow equal to half of the total air flow (smaller units). » Use of corridor as a mixing plenum on return: CRAC units that control underfloor pressure taking air from room (better air distribution even with fewer Air Handlers) » Economizer mode when fresh air is low enough to achieve the desired temperature in the mix: AHU control on supply temperature Room air Exhaust air Fresh air Supply air Room air MIX 9°C 90%rH 17°F 65%rH 25°C 40%rH 50% 50% 17°F 65%rH 50%

11. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" CRAC with AHU as direct Economizer (3) Retrofit with Hot aisle – cold aisle containement » It is possible to use higher temperatures (DB under 25°C) » The AHU can help to keep a good level of separation of the two air flows (ducts, chimneys,..) » Use of corridor as a plenum with CRAC underfloor distribution to avoid mixing » Fan control based on pressure to guarantee right air flow Room air curtain 25°C 45%rH 25°C 45%rH 33°C 28%rH

12. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" CRAC with AHU as direct Economizer (4) Other installations: intake separate from extraction » Additional air handler or plenum with damper for fresh air introduction » Air extracted from room or hot aisles (more flexibility and less ducts) » Supply temperature control acting on dampers (to be integrated with CRAC control) » Adiabatic humidification is slightly more difficult to install » Partial free cooling with variable speed compressors Return air Exhaust air Fresh air Mixing damper

13. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" 0.0 1.0 2.0 3.0 4.0 5.0 6.0 0% 20% 40% 60% 80% 100% 120% LOAD C.O.P. ON-OFF AC INVERTER DC BRUSHLESS INVERTER BLDC compressors New technologies to increase efficiency at partial load » Possibility to use partial free cooling extending number of economizer mode working hour and possibility to use reduced air flow » Partial free cooling whenever it is possible to have a better temperature to the CRAC inlet » Supply temperature control with modulation

14. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" Weather Data Location: SHANGHAI, ALL REGIONS, CHINA -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 DRY BULB TEMPERATURE - °C -20 -10 0 10 20 30 40 50 -20 -10 0 10 20 30 40 50 60 70 80 90 ENTHALPY -KJPER KILOGRAM OFDRY AIR SATURATION TEMPERATURE -°C -10 -5 0 5 10 15 20 25 DEWPOINTTEMPERATURE-°C Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com 2 4 6 8 10 12 14 16 18 20 22 24 15% 25% 2% 4% 6% 8% RELATIVE HUMIDITY 10% RELATIVE HUMIDITY 20% 30% 40% 50% 60% 70% 80% 90% -20 -15 -15 -10 -10 -5 -5 0 5 5 10 10 15 15 20 20 25 25 30 W ET BULB TEM PERATURE - °C0,74 0,76 0,78 0,80 0,82 0,84 0,86VOLUME-CUBICMETERPERKGDRYAIR 0,88 0,90 0,92 HUMIDITYRATIO-GRAMSMOISTUREPERKILOGRAMDRYAIR data hall fresh air mix Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.comChart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com CRAC with AHU as direct Economizer Possible savings example: traditional design (1) Total free-cooling with full air flow (DB<17°C and x<11g/kg) 4283 h Evaporative cooling (DB>17°C but final DP< setpoint 10,5°C) 124 h Mechanical cooling 4353 h (49%) Humidification (fresh air with DP<10,5°C) 3653 h (2) Total free-cooling with half air flow (DB<9°C) 2283 h Evaporative half air flow (DB>9°C but final DP<10,5°C) 1097 h Mechanical cooling 5380 h (61%) Humidification (fresh air with DP<10,5°C) 2259 h Partial free-cooling on the return potential (DB<25°C) *** 6908 h ***check dehumidification

15. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" Weather Data Location: SHANGHAI, ALL REGIONS, CHINA -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 DRY BULB TEMPERATURE - °C -20 -10 0 10 20 30 40 50 -20 -10 0 10 20 30 40 50 60 70 80 90 ENTHALPY -KJPER KILOGRAM OFDRY AIR SATURATION TEMPERATURE -°C -10 -5 0 5 10 15 20 25 DEWPOINTTEMPERATURE-°C Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com 2 4 6 8 10 12 14 16 18 20 22 24 15% 25% 2% 4% 6% 8% RELATIVE HUMIDITY 10% RELATIVE HUMIDITY 20% 30% 40% 50% 60% 70% 80% 90% -20 -15 -15 -10 -10 -5 -5 0 5 5 10 10 15 15 20 20 25 25 30 W ET BULB TEM PERATURE - °C 0,74 0,76 0,78 0,80 0,82 0,84 0,86VOLUME-CUBICMETERPERKGDRYAIR 0,88 0,90 0,92 HUMIDITYRATIO-GRAMSMOISTUREPERKILOGRAMDRYAIR data hall fresh air cold aisle Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.comChart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com CRAC with AHU as direct Economizer Possible savings example: hot aisle cold aisle layout with cointainement (1) Total free-cooling with full air flow (DB<25°C but DP<15°C) 5007 h Evaporative cooling (DB>25°C but final DP< set-point 15°C) 25 h Mechanical cooling 3728 h (42%) Humidification (fresh air with x<5,5 g/kg) 2421 h (2) Total free-cooling with half air flow (DB<17°C) 4356 h Evaporative half air flow (DB>17°C but final DP<15°C) 290 h Mechanical cooling 4114 h (47%) Humidification (fresh air with DP<5,5°C) 2389 h Partial free-cooling potential on the return (DB<33°C) *** 8624 h

16. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" TOPICS 1. CRAC vs AHU: traditional vs innovative? 2. CRACs and AHU for direct free cooling 3. Humidity Control 4. CRACs and AHU for indirect free cooling " CRAC and AHU: Energy saving in the Synergy of High Efficiency Technologies "

17. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" Weather Data Location: SHANGHAI, ALL REGIONS, CHINA -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 DRY BULB TEMPERATURE - °C -20 -10 0 10 20 30 40 50 -20 -10 0 10 20 30 40 50 60 70 80 90 ENTHALPY -KJPER KILOGRAM OFDRY AIR SATURATION TEMPERATURE -°C -10 -5 0 5 10 15 20 25 DEWPOINTTEMPERATURE-°C Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com 2 4 6 8 10 12 14 16 18 20 22 24 15% 25% 2% 4% 6% 8% RELATIVE HUMIDITY 10% RELATIVE HUMIDITY 20% 30% 40% 50% 60% 70% 80% 90% -20 -15 -15 -10 -10 -5 -5 0 5 5 10 10 15 15 20 20 25 25 30 W ET BULB TEM PERATURE - °C 0,74 0,76 0,78 0,80 0,82 0,84 0,86VOLUME-CUBICMETERPERKGDRYAIR 0,88 0,90 0,92 HUMIDITYRATIO-GRAMSMOISTUREPERKILOGRAMDRYAIR data hall fresh air mix supply Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.comChart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com CRAC with AHU as direct Economizer Humidity control issues » The introduction of fresh air during winter for direct freecooling reduces humidity » Use of adiabatic humidifiers is easier with single air handler mixing hot air (even with double systems for winter/summer operation on return/supply) » When extraction and fresh air intake are separated room level humidification can be necessary for adiabatic » High humidity limits direct freecooling

18. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" CRAC with AHU for humidification Use of additional air handler for adiabatic humidification in legacy datacenter » Use of air handler for adiabatic humidification (i.e. to avoid use of electrical humidifiers) with more space and keeping water out of server room » In the example the power saving is about 100 kW (vs 420 kW for cooling) » There is an additional side effect of evaporative cooling » Partial air flow for humidification only » Freecooling as an option Return air Adiabatic Humidification Supply air

19. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" Humidity control with recirculation Example: In Row cooling without de-humifification. Low humidity for ambient conditions » Installation in Scandinavia » 100 kW cooling power » Temperature in cold aisle 24°C » Design temperature in hot aisle 34°C » 4 units with full recirculation: water temperature 15°C (higher than dew point). No dehumidification » Volume of the room: approximately 200 m3 » Minimum humidity in cold aisle: 32% (@24°C it is 5,5 g/kg ASHRAE minimum recommended) » Humidity measured: 14,5% with 24°C this is 2,5 g/kg Hot aisle containment

20. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" Humidity control with recirculation A new approach: Total Moisture Content » Volume of the room: 200 m3 » Total Moisture Content in minimum-desired conditions : 0,6 vs 0,92 kg. » Max moisture using recommended limit (60%r.h.) is 2,16 kg. » Hypothesis: dehumidification performed by In row AC units in transitory conditions but mainly by the infiltration of fresh air with low humidity and diffusion phenomena due to different humidity concentrations » Hypothesis for calculation: high infiltration 0,5 vol/h (to keep into account diffusion and door open condition » The equivalent is a reduction of 850 g/h. In 0,5 h the humidity goes down from acceptable to minimum value. Experimental data show slower reduction. » With 4 kg/h humidifier the Total Moisture Content can be brought from minimum to maximum in 15 minutes » Possible use of a small unit for humidification only (AHU?) 100 m3/h @ -20°C 95% 0,6 g/kg abs H

21. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" TOPICS 1. CRAC vs AHU: traditional vs innovative? 2. CRACs and AHU for direct free cooling 3. Humidity Control 4. CRACs and AHU for indirect free cooling " CRAC and AHU: Energy saving in the Synergy of High Efficiency Technologies "

22. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" IEC combined with CRACs. Traditional design with recirculation (no fresh air introduction) » Air handler with Heat Exchanger with 50% efficiency » Same air flow as the total of CRACs distribution in the room or in the corridor » Hours of cooling depend on W.B. » With half air flow the total cooling is not possible » Possible partial freecooling on return with variable speed compressors 17°C 60%rH 14°C 45%rH 9°C 95%rH 25°C 40%rH Ambient Process air Exhaust air Return air AHU supply air Indirec Evaporative Cooling

23. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" IEC combined with CRACs. Installation with containment – higher tempeartures » Cold aisle containment allows higher temperatures » AHU for IEC with supply in the corridor (use of CRACs for air distribution) » Total cooling with half air flow for WB<9°C (same as total air flow and low temperature design) » Partial IEC based on the return is possible even with reduced air flows 25°C 45%rH 24°C 45%rH 17°C 95%rH 33°C 28%rH 25°C 45%rH

24. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" Weather Data Location: SHANGHAI, ALL REGIONS, CHINA -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 DRY BULB TEMPERATURE - °C -20 -10 0 10 20 30 40 50 -20 -10 0 10 20 30 40 50 60 70 80 90 ENTHALPY -KJPER KILOGRAM OFDRY AIR SATURATION TEMPERATURE -°C -10 -5 0 5 10 15 20 25 DEWPOINTTEMPERATURE-°C Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com 2 4 6 8 10 12 14 16 18 20 22 24 15% 25% 2% 4% 6% 8% RELATIVE HUMIDITY 10% RELATIVE HUMIDITY 20% 30% 40% 50% 60% 70% 80% 90% -20 -15 -15 -10 -10 -5 -5 0 5 5 10 10 15 15 20 20 25 25 30 W ET BULB TEM PERATURE - °C 0,74 0,76 0,78 0,80 0,82 0,84 0,86VOLUME-CUBICMETERPERKGDRYAIR 0,88 0,90 0,92 HUMIDITYRATIO-GRAMSMOISTUREPERKILOGRAMDRYAIR fresh process air IEC hot aisle cold aisle/room supply low t Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.comChart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com CRAC with AHU as IEC unit Possible savings example: traditional design and high temperature design (1) Total IEC with traditional design (WB<9°C) 3019 h With Evaporative cooling (DB>9°C but WB< 9°C) 675 h (20%) Mechanical cooling 65% Humidification (depends on building and CRAC) --------- Partial free-cooling potential (WB<23°C) 7024 h (1) Total IEC with high temperature design (WB<17°C) 5141 h With Evaporative cooling (DB>17°C but WB< 17°C) 676 h (13%) Mechanical cooling 41% Humidification (depends on building and CRAC ) --------- Partial free-cooling potential (WB<31°C) 8760 h

25. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" » Same design criteria: 1,17 MW supply 17°C 65% return 25°C 40% » Hypothesis of 6 units of the same airflow: total 150000 m3/h (33% of the CRAC airflow) » Units with adiabatic systems for humidification, removing electrode humidifiers (100 kW) » IEC system with cross flow HX (e= 50%) » Variable speed compressors to take advantage of partial freecooling on the return » Hypothesys of 2 working points (worst case of WB) and minimum WB to avoid de-humidification Partial IEC combined with BLDC compressors Example of implementation keeping the same design criteria IEC water atomizer 4 123 5 6 MIX 33% 66% Highest WB Minimum WB 1 26°C 64% r.h. 20 °C 25 % r.h. 2 21,5°C 95% r.h. 11 °C 90 % r.h. 3 25°C 40% r.h. 25°C 40% r.h. 4 23,2°C 45% r.h. 18°C 60% r.h. 5 24,5°C 42% r.h. 22,9°C 45% r.h. 6 17°C 65% r.h. 17°C 65% r.h.

26. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" Weather Data Location: SHANGHAI, ALL REGIONS, CHINA -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 DRY BULB TEMPERATURE - °C -20 -10 0 10 20 30 40 50 -20 -10 0 10 20 30 40 50 60 70 80 90 ENTHALPY -KJPER KILOGRAM OFDRY AIR SATURATION TEMPERATURE -°C -10 -5 0 5 10 15 20 25 DEWPOINTTEMPERATURE-°C Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com 2 4 6 8 10 12 14 16 18 20 22 24 15% 25% 2% 4% 6% 8% RELATIVE HUMIDITY 10% RELATIVE HUMIDITY 20% 30% 40% 50% 60% 70% 80% 90% -20 -15 -15 -10 -10 -5 -5 0 5 5 10 10 15 15 20 20 25 25 30 W ET BULB TEM PERATURE - °C0,74 0,76 0,78 0,80 0,82 0,84 0,86VOLUME-CUBICMETERPERKGDRYAIR 0,88 0,90 0,92 HUMIDITYRATIO-GRAMSMOISTUREPERKILOGRAMDRYAIR fresh process air room supply IEC Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.comChart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com CRAC with AHU as IEC unit Possible savings in the specific example (traditional design and 33% IEC) Air inlet to CRAC Compressor load COP Working hours (yr) Electrical Power No IEC 25°C 100% 3 8760 h 390 kW IEC @highest WB 24,7°C 95,9% 3,17 6792 h <369 kW IEC @minimum WB 22,9°C 73,8% 4 3270 h 295 kW Energy Saving Potential (hour by hour calculation) 944 MWh /yr 0.0 1.0 2.0 3.0 4.0 5.0 6.0 0% 20% 40% 60% 80% 100% 120% LOAD C.O.P. ON-OFF AC INVERTER DC BRUSHLESS INVERTER With a 0,1 €/kWh hypothesis there is a potential saving of 94,400 €/yr For 500 h of humidification the potential is 5000 €/yr

27. www.datacenterdynamics.com Enrico Boscaro – Carel Industries SpA www.carel.com – "CRAC and AHU: Energy saving in the synergy of High Efficiency Technologies" Conclusions Possibilities might come from the synergy of different technologies » A mix of AHU and CRAC can bring savings also in legacy datacenter keeping the same design criteria or constraints and optimizing the costs » Savings are optimized increasing temperatures with hot aisle cold aisle layout » Partial air flow can be considered to optimize TCO » For direct air economizers Direct Evaporative Cooling can be a big potential but humidification need can be remarkable so it is better to have a flexible and modulating system. High humidity can be an issue too. » Partial free-cooling is perfect if combined with variable speed compressors with higher efficiency at partial load. » Control is important to optimize yearly performance of the different devices

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