Data Center Design Guide featuring Water-Side Economizer Solutions with Dynamic Economizer Cooling
Presenter: Jason Koo, P.Eng Sr. Field Applications Engineer STULZ Air Technology Systems jkoo@stulz ats.com
Water Side Economizer Solutions Outline ASHRAE Standards and Guidelines relative to Precision Cooling ASHRAE 127 2012 CEC Requirements ASHRAE TC 9.9 2011 ASHRAE 90.1 2010 Air & Water Side Economizers
ASHRAE 127 2012 New Test Standards ASHRAE 127 2012 Method for Testing for Rating Computer and Data Processing Room Unitary Air Conditioners defines performance test standards The purpose is to establish a uniform set of requirements for rating precision cooling equipment Significant changes in the 2012 edition 1. Higher return air temperatures, thus increasing efficiency 75, 85, 95, 105 degrees F DB 2. Higher chilled water entering temperatures 3. A testing/rating procedure for equipment 4. A testing/rating procedure for the newer technologies a. Row based cooling systems b. Containment systems
Raising return air temperature using containment With a raised floor (Figure 1) Raised floor is pressurized with cold air from the precision cooling units Cold air passes through perforated floor tiles, taken into the servers, heated and exhausted into the contained hot aisle Hot air is directed back to the ceiling plenum, then returned to the CRAH units With a slab floor (Figure 2) Utilizes server racks that have a top ducted chimney connection A CRAH with front discharge floods the space with cold air, allowing the servers to take cold air in from the front Hot air is discharged out to the chimney and returned to the CRAH unit via a return duct or ceiling plenum
Update of CEC Requirements On July 1 st 2014 Adopting the SCOP requirements of ASHRAE 90.1 2010 which are based on the ASHRAE 127 2007 test standard (75 F and 52 DP EAT s) Requires 100% testing of a representative of each unit that will be offered for sale in the state of California Elimination of non adiabatic humidification and reheat
Humidification Improves Efficiency Feature Infrared Humidifier STULZ Ultrasonic Technology Infrared Ultrasonics Capacity (lbs./hr.) 22 18 Energy Consumption (Watts) 9,600 585 Water Requirements Maintenance Requirements Non conditioned city water ½hour to remove mineral buildup in pan Demineralized water using RO and DI No cleaning of ultrasonic required Humidification Energy Comparison Humidification Technology Number of Humidifiers Required Watts Consumed Annual Hours Of Operation KW/H per year Cost Per KWH Annual Cost of Electricity Infrared 98 x 9,600 x 3,725 x 3,504,480 x $0.11 x $385,493 Annual Savings Ultrasonic 120 x 585 x 3,725 x 261,495 x $0.11 x $28,764 $356,728 Free Cooling Energy Savings Adiabatic cooling provided (BTU/h) Total KW/H per year* Cost Per KWH Annual Cost of Electricity Ultrasonic 2,095,200 799,973 x $0.11 $87,997 Combined Humidification and Free Cooling Energy Savings $444,725 *KWH based on 1.23 KW/Ton for air cooled chiller
STULZ Ultrasonic Humidifier DRH Direct Room Humidifier Mounts below the ceiling in a conditioned space On wall or column with factory furnished mounts Suspended from above in open space Integral blower and washable filter Absorption distance determined by RH of room
Ultrasonic Humidifier in Space
STULZ Ultrasonic Humidifier DAH Ducted Air Humidifier Mounts in moving air stream of AHU or ductwork Multiple humidifiers assembled on factory rack system Air velocity design similar to heating/cooling coils Factory accessories for optimized airflow and mist control Absorption distance determined by RH of airstream
Ultrasonic Humidifier in Duct
ASHRAE Standards and Guidelines What Has Changed 2004 Recommended (old) 2011 Recommended (new) Inlet Air Temperature Moisture Content 68 77.0 F DB 40% RH to 55% RH 64 80.6 F DB 41.9 F DP to 60% RH & 59 F DP 2011 Allowable (A1) 59 89.6 F DB 20 80% RH up to 62.1 F DP ASHRAE TC9.9 2011 Allowance for increased delta T across server equipment Offers an opportunity to raise the return air temperatures to the cooling equipment Current trend for maximum efficiency in the data center isolate the hot return air from the cold supply prevent air mixing Opportunity to raise the delta T between the supply air temperature from the cooling equipment to the IT equipment and the return air temperature from the IT equipment to the cooling equipment
Coil Calculations and Optimization Higher return air temperature to the CRAC/CRAH equipment increases cooling efficiencies Increase Entering Air (to CRAH) Improve Net Sensible Capacity Decrease CRAH Unit Power Decrease Chiller Power Mix and match to achieve optimal conditions More economizer hours, lower PUE, and lower energy costs
ASHRAE 90.1 2010 Since data centers have been identified to consume ~3% of the total energy produced in the U.S., the former process cooling exemption is gone. The DOE is mandating that all states adopt ASHRAE 90.1 2010, or a more stringent standard, for new data center design and construction by October 2013. Water side economizers must meet 100% of the expected load with cooling towers when operating at or above 40 F dry bulb / 35 F wet bulb and with dry coolers when operating at or below 35 F dry bulb. Evolution of Measuring Efficiency ASHRAE 127 2007 guideline for Sensible Coefficient of Performance (SCOP) ASHRAE 90.1 2010 guideline for SCOP (used for this presentation) ASHRAE 127 2012 guideline for Net Sensible Coefficient of Performance (NSenCOP)
Air Side Economizers Air Side Economizers Direct Free Cooling System, but customer provides damper system and filtration, and controls its operation. Outside Air & Moisture Warmer / High Humidity Within Proper Range Colder than Desired Operation Dampers close & the CRAC/CRAH revert to traditional operation Outside air is directly introduced through the dampers in the mixing box Dampers mix outside air & return air to achieve desired temperature
Air Side Economzer Vertical & Horizontal Mixing Boxes Vertical and horizontal mixing boxes for air-side economizer options using floorstanding CRAC s or CRAH s CRACs or CRAHs with an integrated mixing box and damper controls provide direct free cooling Units attached to the top of a CRAC or CRAH in a vertical or horizontal position Pre-filter and freeze protection damper options Mixes outside and return air depending on outside air conditions Full economizer controls provided by the CRAC or CRAH
Air Side Economzer
Air Side Economizer CyberHandler (AHU) with Direct Air Economizer, Direct Adiabatic Cooling, and DX for trim Direct Air-Side Economizer Outside air (less than supply air temp) is directly introduced into the data center Direct Adiabatic Cooling The outside air is cooled with an adiabatic system and directly introduced into the data center Direct DX Cooling The outside and/or return air is cooled with a DX evaporator coil and directly introduced into the data center
Air Side Economizer CyberCon (Modular/Container) with Direct Air Economizer, Direct Adiabatic Cooling, and DX for trim Direct Air-Side Economizer Outside air (less than supply air temp) is directly introduced into the data center Direct Adiabatic Cooling The outside air is cooled with an adiabatic system and directly introduced into the data center Direct DX Cooling The outside and/or return air is cooled with a DX evaporator coil and directly introduced into the data center
Air Side Economizer DX Cooling Section with Humidification DX Coil used for trim capacity Ultrasonic Humidifier used for humidification Ultrasonic Humidifier DX Coil An option is to add an adiabatic pad for direct adiabatic cooling before the DX Coil Ex. Nortec V Profile Evaporative Pad
Air Side Economizer CyberHandler with Indirect Air Economizer, Indirect Adiabatic Cooling, and DX for trim Indirect Adiabatic Cooling Module Indirect Air-Side Economizer Outside Air (less than supply air temp) passes through an air-to-air heat exchanger to indirectly cool the data center return air Indirect Adiabatic Cooling The return air is indirectly cooled via an air-to-air heat exchanger that has an adiabatic spray applied to it
DX CRAC with Economizer Coil and Condenser Loop Used with the following Water Side Economizers: Traditional Economizer Cooling Variable Economizer Cooling Evaporative Tower Economizer Cooling
Types of Water Side Economizers DX Economizer Solutions Traditional Economizer Variable Economizer Evaporative Tower Economizer CW Economizer Solutions Dual Source Chilled Water Economizer Dynamic Economizer Cooling Standard Optimized
Traditional Economizer Cooling Comparison Traditional Economizer Cooling Constant fan speed dry cooler fans cycled on and off based on fluid temperature Constant speed pumps Water/glycol cooled free cooling CRACs DX cooling coil and water/glycol free cooling coil Comparison of a CRAC to a CRAC with Free Cooling Coupled with a Constant Speed Fan Dry Cooler Baltimore, MD Salt Lake City, UT (4,500 ft altitude) Portland, OR
Variable Economizer Cooling Comparison Variable Economizer Cooling Variable fan speed dry cooler fan speed controlled based on fluid temperature Variable speed pumps controlled based on fluid temperature Water/glycol cooled free cooling CRACs DX and water/glycol free cooling coil Comparison of a CRAC to a CRAC with Free Cooling Coupled with a Variable Speed Fan Dry Cooler Baltimore, MD Salt Lake City, UT (4,500 ft altitude) Portland, OR
Evaporative Tower Economizer Cooling Comparison Evaporative Tower Economizer Cooling Closed loop evaporative cooling tower Controlled based on fluid temperature Constant speed pump Water/glycol cooled free cooling CRACs DX and water/glycol free cooling coil Comparison of a CRAC to a CRAC with Free Cooling Coupled with an evaporative cooling tower Baltimore, MD Salt Lake City, UT (4,500 ft altitude) Portland, OR
Comparison of DX Economizer Cooling % Reduced Energy Baltimore MD Traditional Economizer Cooling verses DX Cooling 13% Variable Economizer Cooling verses DX Cooling 31% Evaporative Cooling Tower Economizer Cooling verses DX Cooling 32%
Dual Source Chilled Water Economizer Cooling Dual Source Chilled Water Economizer Cooling Evaporative cooling tower and pump controlled based on fluid temperature Air Cooled Chiller and pump controlled based on fluid temperature CRAH units dual circuited interlaced chilled water cooling coil Comparison of a CRAH Coupled with an Air Cooled Chiller to a CRAH with Dual Coils Coupled to an Air Cooled Chiller and Evaporative Cooling Tower Baltimore, MD Salt Lake City, UT (4,500 ft altitude) Portland, OR
Dynamic Economizer Cooling (DEC) A Dynamic Economizer Cooling (DEC) system (state of the art water side economizer solution) Evaporative cooling tower Air cooled chiller Cooling tower and chiller pumps Control mixing valves CRAH units Required cooling fluid temp < ambient conditions = operates in the cooling tower mode Required cooling fluid temp > ambient conditions = operates in the chiller assisted cooling mode System minimizes hours of chiller operation and optimizes opportunity for economization
Warm Water Cooling
Power Usage Effectiveness (PUE) Evaluating Power Usage Effectiveness Power Usage Effectiveness (PUE) Measurement of data center efficiency (by The Green Grid) PUE = (IT Load + Total Power) / IT Load IT Load is the effective processing equipment power of the data center Total Power includes security, cooling, lighting, fire monitoring, etc. Industry Benchmarks PUE < 1.6 considered very good PUE < 1.2 is state of the art
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Utility Rebates Further Improve ROI Utility Rebates Further Improve ROI Many utility companies are running out of capacity Most utility companies are offering incentive programs for: Retrofitting existing cooling equipment Replacing cooling equipment Installing new energy efficient cooling equipment Most energy efficient solutions available Sales Rep and Applications Engineering can: Help calculate the energy savings for STULZ solutions Provide you with an energy analysis report Sales Rep can: Introduce you to your local utility Initiate the rebate process by starting the paperwork Customers have received hundreds of thousands of $ s in rebates Outdoor Cooling Indoor Cooling Retrofit and Conditioning
Conclusions By providing an economizer, power usage is significantly reduced during cooling ambient conditions. By elevating return air temperature and elevating water temperatures, effective economizer hours are increased. Increase in effective economizer hours will reduce energy consumption of the cooling equipment. Reduction of energy by cooling equipment equates to smaller PUE values. Additional Savings Potential (Energy and Capital) Eliminate the raised floor by utilizing CRAH s with front discharge and racks with integrated hot air containment (entire white space used as a cold aisle) Reduce chiller requirements and related maintenance, by specifying/sizing only for the minimum trim capacity required Reduce gen set requirements and related maintenance, by specifying/sizing for the much lower energy required by the system
Presenter: Jason Koo, P.Eng Sr. Field Applications Engineer STULZ Air Technology Systems jkoo@stulz ats.com