1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T Series L TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Supplement 11 (12/2014) SERIES L: CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT ITU-T L.1300 Supplement on a verification te
2、st and feasibility study of energy and space efficient cooling systems for data centres with high density ICT devices ITU-T L-series Recommendations Supplement 11 L series Supplement 11 (12/2014) i Supplement 11 to ITU-T L-series Recommendations ITU-T L.1300 Supplement on a verification test and fea
3、sibility study of energy and space efficient cooling systems for data centres with high density ICT devices Summary Supplement 11 to the ITU-T L series of Recommendations refers to the best practices defined in Recommendation ITU-T L.1300. More precisely, this Supplement provides firstly an introduc
4、tion to a verification test and feasibility study of energy and space efficient cooling systems for data centres with high density ICT devices. Secondly, trial calculations of energy conservation benefits with respect to the application to a full-scale data centre are then reported. History Edition
5、Recommendation Approval Study Group Unique ID* 1.0 ITU-T L Suppl. 11 2014-12-19 5 11.1002/1000/12439 Keywords Best practice, data centre, energy efficient, information and communication technology and climate change (ICT an outline of verification and testing methodologies; verification test results
6、; and trial calculations of energy conservation benefits calculations results when applied to a full-scale data centre. 2 Definitions This Supplement defines the following terms: 2.1 power density: The energy consumption of ICT equipment per rack cabinet of floor area of a server room. 2.2 space eff
7、iciency: The ratio of floor area employed for ICT equipment in relation to the total floor area of the building. 3 Abbreviations and acronyms This Supplement uses the following abbreviations and acronyms: AHU Air Handling Unit WB Wet-Bulb 4 Introduction 4.1 Background In his speech to the General As
8、sembly of the United Nations in September 2009, Prime Minister Hatoyama stated Japans international pledge to reduce CO2 emissions by 25% of 1990 levels by the year 2020 as a mid-term target. As a contribution to this target, a “world-leading reduction in environmental impact“ was also proposed for
9、the “Haraguchi Vision“. At the same time, there is no method for measuring the reduction in CO2 emissions within the internationally recognized field of ICT. With 2010 as the first target period, work on providing advice on methods of evaluating the effects of CO2 reductions for ICT commenced at the
10、 International Telecommunication Union (ITU), and international standardization for ICT on climate change has been strengthened. Within the context of information and communications, the importance of data centres, which form the foundation of information and communications, has increased with the d
11、evelopment of cloud computing and the rapid progress in ICT. Furthermore, in business activities, in terms of improving the efficiency of operations, rapid progress has been achieved in ICT, and the demand for data centres, the foundation of the ICT infrastructure, is growing rapidly. Data centres h
12、ouse large numbers of ICT 2 L series Supplement 11 (12/2014) devices (e.g., server storage network devices) for the processing and storage of a wide variety of data and have air conditioning equipment to cool the interiors of the buildings. Accordingly, the consumption of power, in association with
13、this rapid expansion of demand for data centres, is itself growing rapidly. The proportion of power required by air conditioning equipment for such cooling is high compared with the power consumed by the ICT devices, and a reduction in the power consumption of data centres is a matter of considerabl
14、e importance in improving the efficiency of air conditioning equipment, and in improving energy conservation. Furthermore, in Japan, the majority of data centres of telecommunication operators are located on sites in the suburbs of the capital and other large cities, and construction of space-effici
15、ent data centres is therefore a matter of importance. Equipment for the verification and testing of various cooling methods used for data centres was therefore constructed, and cooling efficiency measured and verified. Energy consumed with the various cooling methods was calculated, with usage of en
16、ergy and space included, and a high-efficiency method of air conditioning determined. 4.2 Objective Air conditioning used in data centres involves blowing chilled air from the server room floor to supply chilled air to the inlets of the server racks, and thus removing the heat generated by the ICT d
17、evices. This system is often referred to as “floor supply air conditioning“. For data centres located in cold areas, power consumption for air conditioning can be reduced by using natural energy from exterior air and snow. This has considerable possibilities, and examples are in use, and planned, bo
18、th in Japan and overseas. In Japan, on the other hand, the majority of data centres of telecommunication operators are located on sites in the suburbs of the capital and other large cities, and efficient use of the limited space available at these sites, and the need for high energy efficiency data
19、centre equipment, is of clear importance. In existing server rooms with high-load and high-density racks, air conditioning power consumption of various cooling methods was therefore tested and verified to investigate the optimum specifications and energy conservation benefits for air conditioning eq
20、uipment in high power density data centres. 5 Outline of verification and testing 5.1 Experimental equipment Figure 1 shows an outline of the equipment employed in verification and testing. This testing was conducted at the Hitachi Plant Technologies Ltd., Matsudo Research Laboratories (Matsudo City
21、, Chiba Prefecture), using a simulated server room and test air conditioning equipment. The simulated server room contained simulated server equipment with built-in heaters, and was mounted on a free-access floor. The facilities comprised a cold aisle supplying chilled air from the air conditioning
22、equipment, and a hot aisle facing the server rack exhaust. Test air conditioning equipment comprised a floor supply air conditioner employing conventional air conditioning and outdoor air cooling, an evaporative cooling unit, and a spot cooling unit. The test equipment comprised eight simulated serv
23、ers generating 8 kW of heat per rack. The floor supply air conditioner had a cooling capacity of 64 kW with an airflow of 20 000 m3/hr, and the evaporative cooling unit had a cooling capacity of 32 kW with an airflow of 10 000 m3/hr. One of each was installed. Four spot cooling units, each with a co
24、oling capacity of 15 kW/unit, were also installed. L series Supplement 11 (12/2014) 3 Figure 1 Outline of a verification test facility The typical floor supply air conditioning method was of the under-floor type in which cooling is achieved by supplying cooled air from multiple floor outlets. Hot in
25、terior air discharged from the hot aisle into the interior upper airspace is drawn from the top of the floor supply air conditioning equipment, dehumidified and cooled to the specified temperature with chilled water inside the air conditioning equipment. The cooled air is then supplied to an under-f
26、loor chamber. During testing, the temperature of the air supplied from the floor supply air conditioning equipment was maintained at 18C 2C. Outdoor air cooling employs a floor supply air conditioner supplying cold air to the room, outdoor air is passed through ducts to the air conditioner, and an e
27、xhaust fan discharges this air to the outside. As with conventional air conditioning, this method cools by supplying air conditioned air from multiple perforated tiles on the floor in the room. When the temperature of the outdoor air is low, it is passed to an air conditioner, mixed with high-temper
28、ature return air from the room cooled and the humidity is adjusted as necessary, and supplied to the under-floor chamber. During testing, the temperature of the air supplied from the floor supply air conditioning equipment was maintained at 18C 2C. In addition to floor supply air conditioning equipm
29、ent which supplies cold air to the room, the evaporative cooling methods employs an evaporative cooling unit comprised of an evaporative cooler and direct sensible heat exchanger, an external fan to pass exterior air over the unit, and a circulating fan to circulate return air. This interior return
30、air is cooled by humidified outdoor air that is cooled by humidification using an evaporative cooling unit, mixed directly with air circulated internally, and introduced into the air conditioning equipment. Chilled water is then used to dehumidify and cool the air to the specified temperature via co
31、oling coils within the air conditioning equipment, and the air is then supplied to the room via the under-floor chamber. During testing, the temperature of the air supplied from the floor supply air conditioning equipment was maintained at 18C 2C. In addition to floor supply air conditioning equipme
32、nt to supply chilled air to the room, the spot cooling method employs a spot cooling unit using the natural circulation of a refrigerant for heat transport. A water-cooled condenser is used to condense the refrigerant evaporated in the spot cooling unit. The spot cooling unit, using the natural circ
33、ulation of a refrigerant, is installed between the server racks and the ceiling, and draws in hot return air discharged from the hot aisle into the space below 4 L series Supplement 11 (12/2014) the ceiling, evaporating the refrigerant in the cooling coils in the cooling unit, and cooling the return
34、 air to a specified temperature, and supplying it to the cold aisle. The refrigerant evaporated in the cooling coils employs the natural circulation of the refrigerant occurring with the difference in density at the vapour-liquid interface. Heat is transported outside the room by circulating the ref
35、rigerant through the water-cooled condenser. During testing, the temperature of air supplied to the floor supply air conditioning equipment was maintained at 18C 2C, and the temperature of the air from the spot cooling unit was maintained at 23C 2C. Testing was also conducted using only spot cooling
36、, without floor supply air conditioning equipment. Figure 2 shows an outline of measurement in verification and testing. Sensors to measure a range of data were installed in the test room and in the vicinity of the air conditioning equipment. The data was recorded with a data logger. In order to eva
37、luate the air conditioning efficiency of each type of air conditioning equipment, this testing measured power consumption not only of IT devices, but also of floor supply air conditioning equipment, refrigerators, chilled water pumps, blowers used in evaporative cooling systems, and spot cooling uni
38、ts. Furthermore, chilled water return temperature, temperature of the return air from the floor supply air conditioner, evaporative cooling unit return air temperature, outdoor air temperature and humidity, chilled water flow, and supply and discharge water flows, were also measured. Furthermore, in
39、 order to evaluate the interior temperature and thermal environment, inlet and discharge temperature for the server racks, air conditioning equipment supply and discharge temperatures, and spot cooling unit supply and discharge temperatures, were measured with temperature and humidity sensors. This
40、data was measured continuously at intervals of five minutes or less. Figure 2 Outline of measurement points L series Supplement 11 (12/2014) 5 5.2 Points investigated The following investigations of air conditioning energy efficiency were conducted for each air conditioning method to evaluate the ch
41、aracteristics and energy conservation properties of each. (1) Cooling characteristics of outdoor air cooling (2) Cooling characteristics of evaporative cooling (3) Cooling characteristics of spot cooling (4) Air conditioning methods and power consumption To evaluate space efficiency and air conditio
42、ning efficiency when applied to an actual data centre, a data centre with 500 server racks was assumed when developing the basic equipment plan and calculating annual power consumption. 6 Verification testing and results 6.1 Cooling characteristics of outdoor air cooling Figure 3 shows an example of
43、 trends in server rack intake temperature and air conditioner supply temperature under the average outdoor air conditions (outdoor air enthalpy approximately 13 kJ/kg) for Tokyo in January. It shows data measured at 64 kW (load ratio 100%) of heat generated by the ICT equipment with outdoor air cool
44、ing. With combined outdoor air cooling and conventional air conditioning, low-temperature outdoor air is mixed with room return air, the mixture humidified to the specified humidity with the evaporative humidifier in the air conditioner, its temperature adjusted to the required supply temperature, a
45、nd then supplied to the room. The air conditioner supply temperature status is controlled to a stable 18C 0.5C. Furthermore, the maximum server rack inlet temperature was verified to be approximately 20C to maintain a similar environment to that of typical air conditioning. Figure 3 Example of air c
46、onditioning in an outdoor air cooling system Figure 4 shows outdoor air enthalpy and power consumption (single chilling system, chilling system, transport). When outdoor air enthalpy is increased, the amount of outdoor air required to handle the heat generated in the room increases. This is apparent
47、 in the trend towards increased transport power with increased outdoor air enthalpy. With this method, exhaust fans are installed to discharge the same amount of room air to the outside. In comparison with conventional air conditioning, power consumption of distribution equipment increases, however
48、power consumption of a chilling system can be halted completely, thus saving large amounts of energy. Testing showed that, under the average outdoor air conditions prevailing in Tokyo in January (temperature 7.0C, relative humidity 41%, enthalpy 13 kJ/kg), a 47% reduction in air conditioning power c
49、onsumption is possible in comparison with conventional air conditioning. 6 L series Supplement 11 (12/2014) Figure 4 Outdoor air enthalpy and distribution power consumption 6.2 Cooling characteristics of evaporative cooling Figure 5 shows an example of trends for inlet temperature of an evaporative-cooled server rack, and air conditioning air supply temperature under outdoor air conditions prevailing in Tokyo in January (outdoor air enthalpy 13 kJ/kg). The graphs show actual data recorded for a combination of evaporative cooling and typical
