Measurements and predictions of the air distribution systems in high compute density (Internet) data centers

When equipment power density increases, a critical goal of a data center cooling system is to separate the equipment exhaust air from the equipment intake air in order to prevent the IT server from overheating. Cooling systems for data centers are primarily differentiated according to the way they distribute air. The six combinations of flooded and locally ducted air distribution make up the vast majority of all installations, except fully ducted air distribution methods. Once the air distribution system (ADS) is selected, there are other elements that must be integrated into the system design. In this research, the design parameters and IT environmental aspects of the cooling system were studied with a high heat density data center. CFD simulation analysis was carried out in order to compare the heat removal efficiencies of various air distribution systems. The IT environment of an actual operating data center is measured to validate a model for predicting the effect of different air distribution systems. A method for planning and design of the appropriate air distribution system is described. IT professionals versed in precision air distribution mechanisms, components, and configurations can work more effectively with mechanical engineers to ensure the specification and design of optimized cooling solutions.     

数据中心空调系统节能研究

针对数据中心空调系统能耗比例过高问题开展了一系列调研,指出了目前国内数据中心空调系统使用中存在的问题,针对这些问题从空调设备节能、气流组织优化和自然冷源合理利用三方面分析了相关的节能方法与手段,为数据中心空调系统的节能设计与改造提供参考和依据。     

传统数据中心高密度设备散热优化解决方案

结合南京吉山云数据中心某机房案例,介绍了安装12 kW机架的传统数据机房的优化方案,通过理论分析及CFD流场模拟仿真,探讨了针对高密度设备散热和机房局部热点的解决方案.     

空调系统中冷却塔的节能

指出对空调系统中的风机、水泵等的耗能就给予与制冷机组同样的重视,系统节能应整体考虑。分析了冷却塔出水温度对系统性能的影响,举例说明了不同工况的能耗对比。     

Age of air and air exchange efficiency in idealized city models

Wind can provide relevantly clean external (rural) air into urban street network, i.e. city ventilation. The local mean age of air denotes the time it takes for the external air to reach a location after entering the urban canopy layer. The air exchange efficiency denotes the efficiency of flushing the street network with external air. However, difficulties exist in calculating the local mean age of air in a city due to open boundaries. The traditional experimental homogeneous emission method is adapted here in a CFD method to predict the urban local age of air and analyze the air exchange efficiency for city ventilation. Three simple city models are considered, including a round city model, a square city model and a long rectangular city with one main street parallel to the approaching wind or with two crossing streets. The difference in the city shape results in significant difference in the local mean age of air. In the round city of one narrow street, two inflows through street openings converge close to the city centre and exits through the street roof, so the air close to the city centre is relatively old and the air exchange efficiency is low (30%). For a round city with two crossing streets, a slightly non-parallel wind to the main street generates younger air and the higher air exchange efficiency in the city.     

关于完善公共建筑集中空调系统节能评价体系的一些探讨

认为目前的节能评价体系用"年空调总用电量"、"单位空调面积耗电量"不能全面、正确地评价集中空调系统。提出了新的集中空调能效自动跟踪评价系统,该系统对集中空调系统的实时制冷量、各空调用电设备的实时功率、实时用电量、实时能效、历史平均综合能效、实时负荷率、历史平均负荷率等数据进行跟踪、监测、统计并显示。以工程实例说明新的评价系统的应用。     

Evaluation of thermal comfort using combined CFD and experimentation study in a test room equipped with a cooling ceiling

This paper reports a full-scale experimental campaign and a computational fluid dynamics (CFD) study of a radiant cooling ceiling installed in a test room, under controlled conditions. This research aims to use the results obtained from the two studies to analyze the indoor thermal comfort using the predicted mean vote (PMV). During the whole experimental tests the indoor humidity was kept at a level where the condensation risk was minimized and no condensation was detected on the chilled surface of the ceiling. Detailed experimental measurements on the air temperature distribution, surface temperature and globe temperature were realized for different cases where the cooling ceiling temperature varied from 16.9 to 18.9 °C. The boundary conditions necessary for the CFD study were obtained from the experimental data measurements. The results of the simulations were first validated with the data from the experiments and then the air velocity fields were investigated. It was found that in the ankle/feet zone the air velocity could pass 0.2 m/s but for the rest of the zones it took values less than 0.1 m/s. The obtained experimental results for different chilled ceiling temperatures showed that with a cooling ceiling the vertical temperature gradient is less than 1 °C/m, which corresponds to the standard recommendations. A comparison between globe temperature and the indoor air temperature showed a maximum difference of 0.8 °C being noticed. This paper also presents the radiosity method that was used to calculate the mean radiant temperature for different positions along different axes. The method was based on the calculation of the view factors and on the surface temperatures obtained from the experiments. PMV plots showed that the thermal comfort is achieved and is uniformly distributed within the test room.     

数据中心湖水源自然冷却系统现场性能测试分析

为解决数据中心冷却系统能耗高、能源利用效率低的问题,自然冷却技术得到了广泛应用.以东江湖数据中心湖水源自然冷却系统为测试对象,详细测试了系统的实际运行性能,并讨论了其节能性,旨在为数据中心自然冷却系统运行设计提供实际数据支撑.测试结果表明:湖水源自然冷却系统的综合性能系数高达11,相比国家政策要求(新建大型数据中心PU...     

空调水系统变流量节能控制

强调根据空调负荷变化对水系统进行节能控制具有十分重要的意义。分析了一级泵系统实现变流量运行的可行性,并通过实例说明了其显著的节能效果。     

基于全球典型城市全年气象参数的数据中心空调系统节能性分析

数据中心空调系统能耗与室外气象参数紧密相关,全球不同区域的数据中心空调系统能耗有很大差异.结合全球四大典型城市(纽约、伦敦、北京、上海)的气候特点,总结了数据中心常用水冷式冷水系统的优化措施,分析了优化后国内外数据中心空调系统的节能性.     

间接蒸发冷却用于空调新风预冷的实验研究

从温差换热驱动势和吸湿驱动势出发,分析了间接蒸发冷却换热效率的影响因素,实验研究了新风进口温度、排风进口温度和相对湿度对新风进出口温差和换热效率的影响。     

An integrated modeling tool for simultaneous analysis of thermal performance and indoor air quality in buildings

To analyze the thermal performance and indoor air quality (IAQ) in building simultaneously and quickly, we have developed an integrated modeling tool to simulate the dynamic indoor multi-parameters distributions and concentrations. The tool can take the parameters including indoor temperature, indoor humidity, and pollutant concentrations (e.g., volatile organic compounds (VOC) CO₂, particulate matter (PM)), as well as the heating/cooling load of heating, ventilating, and air-conditioning (HVAC) system into account. It couples a new zonal approach based on room air age. This paper presents the basic concept and flow chart in developing the modeling tool, and demonstrates the tool's application in a hypothetical health care building. The tool could be used for design of HVAC system with IAQ control devices and for the simultaneous analysis of thermal performance and IAQ in buildings.     

隔离病房回风高效过滤器滤菌效率的实验研究

介绍了国外各类高效过滤器的滤菌效率。在安装有高效过滤器的隔离病房回风口进行了发菌实验,计算了B类和C类回风高效过滤器的滤菌效率,证明了当隔离病房回风口安装高效过滤器时,可使用部分循环风。     

Study on inhaled air quality in a personal air-conditioning environment using new scales of ventilation efficiency

A detailed study using computational fluid dynamics (CFD) was conducted on the influence of the difference in the effective diameters of air supply openings (air velocity, assuming the airflow rate to be constant) when using personal air-conditioning (PAC) with isothermal air currents. A new method to analyze the age of air (SVE3*) for individual supplies and the residual lifetime of air (SVE6*) for individual exhausts was developed and proposed. The study focuses on the individual supply openings and exhaust openings in a room with multiple supply openings and exhaust openings when using PAC. PAC with the larger supply opening resulted in less mixture with the surrounding air and a lower age of air than the smaller diameter, which therefore indicated better ventilation characteristics.     

Investigation of air management and energy performance in a data center in Finland: Case study

This is the first research paper on data center from Finland. The objectives of this study are to evaluate air management and energy performance of cooling system and investigate the possibilities of energy saving and reuse in the data center. Field measurements, particularly for long term's IT and facility powers, were conducted. Different performance metrics for the cooling system and power consumption were examined and analysed. Key problem areas and energy saving opportunities were identified. The electrical end use breakdown was estimated. Results show that IT equipment intake conditions were within the recommended or allowable ranges from ASHRAE. The Power Usage Effectiveness (PUE) value for a typical year was about 1.33. Noticeable recirculation of hot air was not observed, but extreme bypass air was found. The air change rate was set much bigger than the recommended ASHRAE's value. There was no heat recovery system. The air management and heat recovery issues therefore need to be addressed. Fan speeds (Computer Room Air-Conditioning Unit) should be reduced and the ventilation rate should be minimized. Further, a simulated heat recovery system was presented demonstrating that the data center could potentially provide yearly space and hot water heating for 30,916 m² non-domestic building.     

重庆市商场类建筑空调工程设计能效比统计分析

提出了空调工程及其子系统设计能效比的计算方法。在对重庆市商场类建筑空调工程的设计情况进行调查统计的基础上,分析了夏季工况下空调工程及冷源系统、水系统、风系统的设计能效比,讨论了提高设计能效比的途径。     

重庆市酒店类建筑空调工程设计能效比调研

调研了重庆市12个酒店建筑的空调工程设计,从冷热源系统、水系统、风系统和整个空调工程等方面分析了空调设计能效比.结果表明,冷热源系统设计能效比对整个空调工程设计能效比的影响最大,设计中要避免冷热源系统装机容量超出设计负荷过多和空调冷热水泵兼用而不作调节,尽量减少采用定风量全空气系统等,可有效提高空调工程设计能效比.调研结果反映出重庆市酒店类建筑空调工程节能设计水平参差不齐,如以各设计能效比的平均值作为设计最低标准,将使公共建筑空调工程的节能设计水平得到提升.     

既有建筑中分体空调器的节能诊断

结合6个体育场馆的实际诊断情况,从设备能效、室外机散热、余热回收、运行管理四个方面分析了既有建筑中分体空调器的节能潜力,提出了相应的改造措施。     

公共建筑集中空调系统微生物及颗粒物测试分析

对哈尔滨市两栋大型公共建筑集中空调系统的送风管道、风机盘管及室内空气中的微生物和颗粒物进行了测试。分析结果表明,空调送风系统对微生物和颗粒物的处理效率不高,对细菌的最高,为73·9%,对0·5~2μm颗粒物的最低,仅有24·4%;系统设备表面和部分送风管道中有真菌生长并向室内传播。认为应适当提高系统过滤器的效率,设置微生物处理装置,并加强对送风系统的维护和清洗。     

深圳T3航站楼雨水池应用于空调冷却系统的研究

针对深圳即将建设的T3航站楼,对雨水池能否用于空调冷却系统进行了研究。结果表明,在深圳地区地表水间接应用于空调冷却系统是不节能的,采用处理后的雨水作为冷却水系统补水,节水省钱效果显著。