XXXXASHRAE手册第19章数据处理和电信设施.doc

CHAPTER 19 DATA PROCESSING AND TELECOMMUNICATION FACILITIES第19章 数据处理和电信设施Design CriteriaHVAC Load considerationsHVAC Systems and ComponentsAir Distribution Ancillary spaces Other Systems and considerations19.1 设计标准19.2 空调负荷注意事项19.3 空调系统和组件19.4 气流组织19.5 辅助空间19.6 其它系统和注意事项DATACOM (data processing and telecommunications) facilities are predominantly occupied by computers, networking equipment, electronic equipment, and peripherals. The most defining HVAC characteristic of data and communications equipment centers is the potential for exceptionally high sensible heat loads (often orders of magnitude greater than a typical office building). In addition, the equipment installed in these facilities typically:数据通信（数据处理和电信）设施主要由计算机、网络设备、电子设备和其它辅助设备组成。数据和通讯设备中心空调最主要的特征是，需要应对极高的显热冷负荷（要比普通的商业办公楼负荷大得多）。另外，空调系统要具有以下这些功能：.Serves mission-critical applications (i.e., continuous operation).Has special environmental requirements (temperature, humidity, and cleanliness).Has the potential for disruptive overheating and equipment failure caused by loss of cooling满足特定的应用（例如：持续运行）；具备特殊环境要求（温度、湿度和洁净度）；在突发性过热和由于设备损坏不能持续制冷的情况下，系统能继续冷却电子设备。 Design of any datacom facility should also address the fact that most datacom equipment will be replaced multiple times with more current technology during the life of the facility. As described in Datacom Equipment Power Trends and Cooling applications (ASHRAE 2005a), typical datacom equipment product cycles are 1 to 5 years, whereas facilities and infrastructure HAVC life cycles of 10 to 25 years. Replacement equipment has historically required more demanding power and cooling requirements.任何数据通信设施的设计时，都要面对这样一个事实：在通信设施的使用寿命期间，随着技术的发展，大量现有的通信设备将会被将来的新设备更换掉。在数据通信设备电源的发展过程和冷却应用中(ASHRAE 2005a)，典型的数据通讯设备产品寿命为1至5年，而空调设施和基础设施的寿命为10年至25年。新设备对电功和制冷量要求的会更大。 Understanding these critical parameters is essential to datacom facility design.了解这些关键因素对数据通信设施的设计是必不可少的。The preparation of this chapter is assigned to TE 9.9, Mission-critical Facilities, Technology Spaces, and Electronic Equipment.由ASHRAE中负责“重要设施、工艺房间与电子设备”的技术委员会TC9.9编著。Design Criteria19.1 设计标准Types of datacom (ASHRAE 2005a) equipment that require air conditioning to maintain proper environmental conditions include数据通信中心(ASHRAE 2005a)的空调系统的工作环境中，包含的数据通信设备类别有：Computer servers (2U and greater)Computer servers (1U, blade, and custom)Communication (High-density)Communication (Extreme-density)tape storageStorage serversWork stations (standalone)Other rack- and cabinet-mounted equipment服务器(2台或更多)服务器(1台, black, and custom)通讯(高密度)通讯(超高密度)磁带存储器存储服务器工作站(独立)其它机架和机柜安装设备Personnel also occupy datacom facilities, but their occupancy is typically transient and environmental conditions (e.g., temperature, noise) are more typically dictated by equipment needs. However, human occupancy in smaller datacom facilities may influence the ventilation air quantity. A data center is a building or portion of a building whose primary function is to house a computer room and its support areas; data centers typically contain high-end servers and storage products with mission-critical functions. Personnel also occupy datacom facilities, but their occupancy is typically transient and environmental conditions are usually more dictated by equipment needs, thereby making it more of a process cooling application rather than comfort cooling. However, human occupancy in smaller datacom facilities may influence ventilation air requirements.工作人员也占用数据通信中心，但其通常是暂时的，所以机房环境条件（如温度，噪音）常由设备的需求决定。虽然工作人员占用的数据通信机房较小，但通风量也会受影响。数据中心可能一个建筑物或建筑物的一部分，其主要功能是容纳一个计算机房和其他附属设施；数据中心通常包含高端服务器和具有重要功能的存储设备。工作人员也占用数据通信中心，但其通常是暂时的，所以机房环境条件（如温度，噪音）常由设备的需求决定，因此空调系统更多的是冷却功能而不是舒适功能。虽然工作人员占用的数据通信机房较小，但对通风设计也会有要求。Overview19.1.1 概述Environmental requirements of datacom equipment vary depending on the type of equipment and/or manufacturer. However, a consortium of server manufacturers has agreed on a set of four standardized conditions (Classes 1 to 4), listed in Thermal Guidelines for Data Processing Environments (ASHRAE 2008). A fifth classification, the Network Equipment-Building Systems (NEBS) class, is typically used in telecommunications.不同类型的设备或制造商，他们的数据通信设备对环境的要求都有所不同。然而，服务器制造厂家们达成了四个标准原则，此四条标准原则列于数据中心冷却指南(Thermal Guidelines for Data Processing Environments ASHRAE 2008)。第五个分类，网络设备构建系统(NEBS)类，通常用于通信。Class 1: typically a datacom facility with tightly controlled environmental parameters (dew point, temperature, and relative humidity) and mission-critical operations; types of products typically designed for these environments are enterprise servers and storage products.第一类：通常数据通信设施有严格控制环境参数（露点，温度和相对湿度）和重要操作; 通信设备服务器和存储设备一般按照此条规定的环境参数设计。Class 2: typically a datacom space or office or lab environment with some control of environmental parameters (dew point, temperature, and relative humidity); types of products typically designed for this environment are small servers, storage products, personal computers, and workstations.第二类：通常数据通信机房或办公室或实验室环境中，会安装有环境参数控制设备（露点温度、温度和相对湿度）；小型服务器、存储设备、个人电脑和工作站一般按照此条规定的环境参数设计。Class 3: typically an office, home, or transportable environment with little control of environmental parameters (temperature only); types of products typically designed for this environment are personal computers, workstations, laptops, and printers.第三类：通常办公室、家庭或者运输环境只需要控制环境温度（温度）；个人电脑、工作站、笔记本电脑和打印机一般按照此条规定的环境参数设计。Class 4: typically a point-of-sale or light industrial or factory environment with weather protection, sufficient winter heating, and ventilation; types of products typically designed for this environment are point-of-sale equipment, industrial controllers, or computers and handheld electronics such as PDAs.第四类：通常销售点或轻工业或工厂，需要有冬季采暖和通风条件。设备销售点、工业控制器、计算机和手持式电子设备如掌上电脑（PDAs）一般按照此条规定的环境参数设计。.NEBS: per Telcordia (2001, 2006), and typically a telecommunications central office with some control of environmental parameters (dew point, temperature and relative humidity); types of products typically designed for this environment are switches, transport equipment, and routers.NEBS(网络设备构建系统):根据Telcordia(2001, 2006)规定，通常电信中心需要有环境控制装置（露点，温度和相对湿度）；交换机、传输设备和路由器一般按照此条规定的环境参数设计。 Because Class 3 and 4 environments are not designed primarily for datacom equipment, they are not covered further in this chapter; refer to ASHRAEs (2008) Thermal Guidelines for Data Center environments for further information.由于第三和第四条不以数据通信设备为主，将不在下面章节中讨论。如想了解更多信息请参考数据中心冷却指南(Thermal Guidelines for Data Processing Environments ASHRAE 2008)。Environmental Specifications19.1.2 环境说明 Table 1 lists recommend and allowable conditions for Class 1, Class 2, and NEBS environments, as defined by the footnoted sources. Figure 1 A shows recommended temperature and humidity conditions for these classes on a psychrometric chart, and Figure 1 B shows allowable temperature and humidity conditions. Note that dew-point temperature and relative humidity are also specified.表1列出了一类、二类和NEBS的建议和允许环境要求，详细介绍见脚注。图1A中，在焓湿图上给出了这两类推荐的环境要求；图1B中，在焓湿图上给出了这两类允许的环境要求。请注意，露点温度和相对湿度也已给出。图 1A 数据中心Class 1、 Class 2和 NEBS推荐的环境参数表1 数据中心Class 1、 Class 2和 NEBS设计参数a. Inlet conditions recommended in ASHRAE (2008). a. ASHRAE (2008)推荐送风温度；b. Percentage values per ASHRAE Standard 52. 1 dust spot efficiency test. MERV values per ASHRAE Standard 52.2b. 平均值按照ASHRAE标准52.1除尘点效率测试，MERV(Minimum Efficiency Reporting Value)值按照ASHRAE标准52.2c. Telcordia (2006).d. Telcordia (2001).e. Generally accepted telecommunications practice. Telecommunications central offices are not generally humidified, but personnel are often grounded to reduce electrostatic discharge (ESD)e. 通信行业常规做法。通信中心通常不需要加湿，但人员需要经常接地，以减少静电放电(ESD, Electro-Static discharge)f. See Figure 2 for temperature derating with altitudef. 见图2温度梯级 Air density also affects the ability of datacom equipment to be adequately cooled. ASHRAEs (2008) Thermal Guidelines for Data Processing Environments suggests that data center products be designed to operate up to 3050 m altitude, but recognizes that there is reduced mass flow and convective heat transfer associated with lower air density at higher elevations. To account for this effect, the guideline includes a derating chart for the maximum allowable temperature of 1 K per 300 m altitude above 900 m (Classes 1 to 4). Figure 2 shows the altitude derating recommended by ASHRAE (2004) for Classes 1 and 2, and for NEBS.空气的密度也会影响数据通信设备的冷却效果。ASHRAE (2008) 数据中心冷却指南(Thermal Guidelines for Data Processing Environments ASHRAE 2008)指出，数据中心设备工作环境的海拔高度不要超过3050m，同时也指出，随着海拔高度的增加，空气的密度逐渐降低，对空气的质量流量和设备的对流换热有一定的影响。考虑到这些因素，数据中心冷却指南给出了一张阶梯图，在海拔900m以上，每升高300m，设备的最大允许温度下降1(1至4类)。ASHRAE (2004)给出，随着海拔高度的增加1类、2类和NEBS的工作环境温度范围。The stated environmental conditions are as measured at the inlet to the data and communications equipment, and not average space or return air conditions.规定的测试条件是：以数据通信设备的进口作为参考点，而不是机房内平均温度或者回风温度。Temperature19.1.3 温度 The allowable temperature range is a statement of functionality, whereas the recommended range is a statement of reliability. Thus, equipment exposed to prolonged high temperatures (and/or to steep temperature gradients) can experience increased failure rates, reduced service life, hardware and/or software failures, and/or thermal shutdown. Exceeding the recommended limits for short periods of time should not be a problem, but running near the allowable limits for months could result in increased reliability issues. Facility designers and operators should strive for continuous operation in the recommended range. ASHRAE (2008) and Telcordia (2001) recommended range is 18 to 27.尽管建议的设备的允许温度范围是可靠的，但它只是一个功能说明。因此，当设备长期暴露在高温环境下（温度波动频率或幅度大），就会提高设备的故障率，降低设备使用寿命，硬件/软件故障率提高，传热性能下降。短时间超过允许温度范围不会对设备造成影响，但如果几个月一直在接近温度范围边界运行，设备的上述问题出现的概率会提高。设计师和管理者都应该努力使设备在允许温度区间内运行。ASHRAE (2008) 和Telcordia (2001)推荐的温度范围是18到27。Fig. 1B Allowable Data Center Class 1, Class 2, and NEBS Operating Conditions图 1B 数据中心1类、2类和NEBS的允许运行参数Not only is air temperature into the electronics critical for reliable operation of components in the electronic box, but the air discharged from the electronics and flowing over the components (cabling, connectors, etc.) at the exit must also be addressed. The recommended ranges apply to inlets of all equipment in the data center (except where IT manufacturers specify other ranges). 送风不仅进入机柜冷却机柜内的电子器件，同时送风从机柜出来后还要冷却其它组件，如电缆，连接器件等。送风的允许温度区间适用于数据中心所有设备，除了IT制造商指定的其它范围。Attention is needed to make sure the appropriate inlet conditions are achieved for the top portion of IT equipment racks. 需要注意的是，选择适当的入口空气参数，以保证IT设备机架的顶部的散热。The inlet air temperature in many data centers tends to be warmer near the top of racks, particularly if warm rack exhaust air dots not HAVC a direct return path to the CRACs. This warmer air also affects the relative humidity, resulting in lower values at the top of the rack. The air temperature generally follows a horizontal lint on the psychometric chart where absolute humidity remains constant but relative humidity decreases.Fig. 2 Class 1, Class 2, and NEBS Allowable Temperature Range Versus AltitudeTemperature Rate of Change Some datacom manufacturers HAVC established criteria for allow-able rates of environmental change to prevent shock to the data and communications equipment. These criteria need to be reviewed for all installed datacom equipment. A maximum inlet temperature change of 5 K/h is recommended by ASHRAE (2008) for Classes 1 and 2. Humidity rate of change is typically most important for tape and storage products. Typical requirements for tape are a rate of change of less than 2 K/h and a relative humidity change of less than 5%/h (ASHRAE 2004). In telecommunications central offices, the NEBS a requirement per Telcordia (2006) for testing new equipment is a rate change (cooling) of 30 K/h. However, in the event of an air-conditioning failure, the rate of temperature change can easily be significantly higher. Consequently, Telcordia (2001, 2006) prescribes testing with a warming gradient of 96 K/h for 15 min. Manufacturers requirements should be reviewed and fulfilled to ensure that the system functions properly during normal operation and during start-up and shutdown Procedures must be in place for response to an event that shuts down critical cooling systems while critical loads continue to operate, causing the space temperature to begin rising immediately. Procedures should also be in place governing how quickly elevated space temperatures can be returned to normal to avoid thermal shock damage. Datacom equipment usually tolerates a somewhat wider range of environmental conditions when not in use sec Table 2.1 in ASHRAE (2008). However, it may be desirable to provide uninterruptible cooling in the room to maintain operating limits and minimize thermal shock to the equipment.26日Humidity High relative humidity may cause conductive anodic failures (CAF), hygroscopic dust failures (HDF), tape media errors and excessive wear, and corrosion. In extreme casts, condensation can occur on cold surfaces of liquid-cooled equipment. Low relative humidity may result in electrostatic discharge (ESD), which can destroy equipment or adversely affect operation. Tape products and media may HAVC excessive errors when exposed to low relative humidity. In general, facilities should be designed and operated to maintain the recommended humidity range in Table 1, but excursions into the allowable range (more typically the equipment specification) should not significantly shorten equipment operating lift.Filtration and Contamination Before being introduced into the data and communications equipment room, outside air should be filtered and preconditioned to remove particulates and corrosive gases. Table 1 contains both recommended and minimum filtration guidelines for recirculated air in a data center. Particulates can adversely affect data and communications equipment operation, so high-quality filtration and proper filter maintenance are essential. Corrosive gases can quickly destroy the thin metal films and conductors used in printed circuit boards, and corrosion can cause high resistance at terminal connection points. In addition, the accumulation of particulates on surfaces needed for heat removal (e.g., heat sink fins) can degrade heat removal device performance. Further information on filtration and contamination in data centers can be found in Chapter 8 of Design Considerations for Datacom Equipment Centers (ASHRAE 2005b) and Particulate and Gaseous Contamination in Datacom Environ meets (ASHRAE 2009)Ventilation Data and communications equipment room air conditioning must provide adequate outside air to achieve the following criteria:Maintain the room undo positive pressure relative to surrounding spaces.Dilute indoor generated pollutants such as VOCs.Satisfy ASHRAE Standard 62.1 requirements.Meet local codes for ventilation for datacom facilities in all spaces, including mechanical, uninterruptible power supply (UPS), and battery rooms The need for positive pressure to keep contaminants out of the room is usually the controlling design criterion in data and communication equipment rooms. Pressurization calculations can be performed using the procedures outlined in Chapter 16 of the 20094SHR4EHandbook-Fundamentals. Chapter 53 of this volume has calculation formulas for achieving pressurization as well as loss of pressure through cracks in walls and at windows. Although most computer rooms HAVC few occupants, calculations should always be performed to ensure that adequate ventilation for human occupancy is provided in accordance with ASHRAE Standard 62.1 and local codes. Internally generated contaminants may make the indoor air quality method the more appropriate procedure; however, maintaining positive pressure usually requires a higher outside airflow.Envelope considerations In addition to meeting state, national, and local codes, there are several other parameters that should be considered in designing the envelope of datacom facilities, including pressurization, isolation, vapor retardants, sealing, and condensation.Pressurization. Datacom facilities are typically pressurized to prevent infiltration of air and pollutants through the building envelope. An air lock or mantrap is recommended for a datacom equipment room door that opens directly to the outside. Excess pressurization with outside air should be avoided, because it makes swinging doors harder to use, and wastes energy through increased fan energy and coil loads.Space Isolation. Datacom equipment centers are usually isolated for both security and environmental control.Vapor Retarders. To maintain proper relative humidity in datacom facilities in otherwise unhumidified spaces, vapor retarders should be installed around the entire envelope. The retarder should be sufficient to restrain moisture migration during the maximum projected vapor pressure difference between datacom equipment room and the surrounding areas.Sealing. Cable and pipe entrances should be scaled and caulked with a vapor-retarding material. Doorjambs should fit tightly.Condensation on exterior glazing. For exterior walls in colder climates, windows should be double or triple-glazed and door seals specified to prevent condensation and infiltration. If possible, there should be no windows. If an existing building is used, windows should be covered.Human Comfort Human comfort is not specifically addressed in Thermal Guidelines for Data Processing Environments (ASHRAE 2008) because the facilities typically HAVC minimal and transient human occupancy. Although telecommunications central offices often HAVC permanent staff working on the equipment, human comfort is not the main objective. Following the recommended Class 1 conditions (see Table 1) in a hot-aisle/cold-aisle configuration may result in comfort co