Influence of Surrounding Structures upon the Aerodynamic and Acoustic Performance of the Outdoor Unit of a Split Air-Conditioner

DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structures upon the aerodynamic and acoustic performance, however they are only limited to the influence of a few parameters on the performance, and practical design of the unit requires more detailed parametric analysis. Three-dimensional computational fluid dynamics（CFD） and computational aerodynamic acoustics（CAA） simulation based on FLUENT solver is used to study the influence of surrounding structures upon the aforementioned properties of the unit. The flow rate and sound pressure level are predicted for different rotating speed, and agree well with the experimental results. The parametric influence of three main surrounding structures（i.e. the heat sink, the bell-mouth type shroud and the outlet grille） upon the aerodynamic performance of the unit is analyzed thoroughly. The results demonstrate that the tip vortex plays a major role in the flow fields near the blade tip and has a great effect on the flow field of the unit. The inlet ring＇s size and throat＇s depth of the bell-mouth type shroud, and the through-flow area and configuration of upwind and downwind sections of the outlet grille are the most important factors that affect the aerodynamic performance of the unit. Furthermore, two improved schemes against the existing prototype of the unit are developed, which both can significantly increase the flow rate more than 6 %（i.e. 100 m3·h～（-1）） at given rotating speeds. The inevitable increase of flow noise level when flow rate is increased and the advantage of keeping a lower rotating speed are also discussed. The presented work could be a useful guideline in designing the aerodynamic and acoustic performance of the split air-conditioner in engineering practice.

Analysis of Cooling Characteristics in Datacenter Using Outdoor Air Cooling

Advancement of the information society has proceeded with the development of information and communication technology, and a demand on a data center has increased. In such a situation, the number of servers is increasing in a data center. Thus, the heat density in a data center is much higher than that of usual offices. And typically, almost 40% of the total power consumption is used for cooling servers in a data center. Thus, cooling effectiveness is one of the most important factors in evaluating the value of the data center. The data center taken up in this paper is located in Ishikari, where is a cold district in Japan. Using the cool outdoor air for cooling servers helps us to cut the power consumption for cooling. This paper first assesses the efficiency of Ishikari data center measuring the temperature of seven parts in a building where the cooling air flowing. Second, this paper describes the most efficient method for the operation and estimates 1.11 of PUE （power usage effectiveness）.

An indoor air aerosol model for outdoor contaminant transmission into occupied rooms

The paper presents a simple model for outdoor air contaminant transmission into occupied rooms. In the model, several factors such as filtration, ventilation, deposition, re-emission, outdoor concentration and indoor sources are included. The model results show that the air exchange rate plays an important role in the transmission of outdoor contaminants into the indoor environment. The model shows that increasing the value of the filtration efficiency decreases the mass concentration of indoor particles. In addition, if outdoor aerosol particles have a periodic behaviour, indoor aerosol particles also behave periodically but smoother. Indoor sources are found to be able to increase indoor concentrations greatly and continuously.

Green Walls as Mitigation of Urban Air Pollution:A Review of Their Effectiveness

Mitigation of urban air pollution has been constrained by the availability of urban spaces for greening.Green walls offer the prospect of greening spaces and surfaces without requiring large areas.Green walls can largely be divided into green facades where the aboveground parts of plants rooted in soil and pots grow directly on,and living walls holding bags,planter tiles,trays and vessels containing substrates in which plants are grown.Green facades and living walls can be continuous or modular with repeating units that can be assembled for extension.This review aims to pres­ent the effectiveness of green walls in removing different types of air pollutants in indoor and outdoor environments.It examined more than 45 peer-reviewed recently published scholarly articles to achieve the aim.It highlights that most of the studies on green walls focus on particulate matter removal and green walls could effectively remove particu­late matter though the effectiveness varies with plant types,air humidity,rainfall and its intensity,leaf area index and contact angle,green wall surface coverage ratio,as well as the height of green walls.Increasing the height of green walls and optimizing their distance from roadsides could promote the deposition of particulate matter.Washing off could regenerate plant surfaces for capturing pollutants.Green walls are also effective in removing NO2,O3,SO2 and CO.Indoor active living walls,when properly designed,could have air purifying performance comparable to a HVAC system.The performance of green walls could be optimized through polycultures,selection of plants,surface coverage and height,and air inflow.

室外通信机柜通风冷却节能性能研究

合肥地区室外空气温度全年约有77.5%的时间在25℃以下,利用CFD数值模拟对机柜进行气流组织优化,结果表明,在合肥地区可采用新风设备给室外通信机柜降温。为了充分利用室外自然冷却资源,在对合肥地区典型室外通信机柜进行现场测量和数值模拟的基础上,提出了空调与新风设备联动策略。该策略缩短了空调的运行时间,从而节约能源,结果表明,空调与新风设备联合运行时的能耗为空调单独运行时的46.8%。

某有机化学实验室项目通风空调系统设计

有机化学实验往往会产生对人体有害的气体,有效的通风空调系统可以避免有害物泄漏,以保证实验人员在工作环境里的安全和健康。不同的有机化学实验室要求不同,其通风空调系统设计也有相应的不同要求。合成实验室通风量大,但对房间温湿度要求不高;分析仪器实验室中仪器设备较多,发热量较大,且对环境温湿度有一定的要求。本文结合某实际工程,对不同功能化学实验室通风量的确定、新风送风温度及空调设置情况和通风系统控制进行了介绍。

定向送风对隔离病房开门时段空气泄漏的抑制效果研究

患有高传染性疾病的患者一般被安置在医院的负压隔离病房中来限制这些疾病在医院内部的传播。然而隔离病人员进出时房门开启可能会导致大量携带有病菌的空气通过房门传递到隔离病房外部走廊,从而引起走廊中的人员被感染。为了减少和预防门开启带来的室内空气泄露问题,有必要使得门开启时室内外交换的气流最小化。为了解决这个问题,我们在隔离病房门口安装有定向气流送风口,通过将定向气流引向隔离病房门口,以减少由门的开启过程,人员移动通过过程和室内外温差引起的室内外空气气流交换量。使用烟雾对流场可视化后发现在门开启或者关闭的过程中使用朝向隔离病房的定向气流能够明显减小室内外的空气交换量。示踪气体测试结果显示,定向气流90L/s时室内外等温条件下可将隔离病房内的空气泄漏量减少38%,而室内外温差3℃时,使用定向气流可减小泄漏量31%。若将定向气流风量调节到190L/s时,等温条件下可减小室内外60%的空气交换量。在室内外存在3℃的温差时,空气交换量可减少39%。尽管测试的定向气流并未能够完全防止空气泄漏,但是它们是可以有效的减少由门的开启,人员通过和室内外温差引起的室内外空气交换量。

空调室外机机壳模态仿真与试验研究

针对某款空调室外机机壳振动噪声大的问题,采用模态分析的研究方法对空调室外机机壳进行结构优化设计。对空调室外机机壳整体进行了不同方案的模态分析,获得整机机壳的前十阶固有频率与振型,将其与锤击法试验所测整机机壳模态结果进行了对比,结果表明:采用顶板无螺栓侧不添加约束条件的模拟方法获得的整机机壳模态更符合试验测试结果,两者误差在3%以内。在此基础上,分别对机壳各结构件进行了模态分析,获得了每一结构件的前3阶固有频率与振型,并对底板、支架关键部件提出了优化方案。通过对室外机机壳减小底板的筋的面积以及增加筋的数量优化钣金件结构,可调整整体结构的固有频率,避开压缩机工作频率以及共振现象产生,有效地改善了振动噪声大的问题。

热压作用下新风系统水力工况分析方法研究

热压作用导致通过竖直立管送风的空调新风系统水力失调且并联管路阻力不平衡,无法计算管网阻抗及进行水力工况分析,针对该问题提出了适用于热压作用下的新风系统水力工况分析方法。该方法将整体管网看作并联的各末端通风支管虚拟闭合环路,求解压阻平衡方程组,拟合了各闭合环路与管网的特性曲线方程,确定了虚拟闭合环路阻抗,实现了热压作用下管网流体流动及流量分配规律的描述。计算中考虑了管网流量与摩擦阻力系数、局部阻力系数的耦合关系。以某办公楼新风系统为例,利用环路阻抗方法对热压作用下管网的水力工况进行了分析,其计算结果与方程组迭代计算结果相吻合,表明了所提方法的准确性。

建筑群风场环境下空调室外机周围热环境分析

空调运行时,外部室外机的散热会受到建筑群内复杂风场环境的干扰,继而影响其运行效率。以布置在凹槽内部的空调室外机为研究对象,考虑建筑群内部的流场变化,研究了正面风、后面风向下室外机运行时的热环境,分析了室外机随楼高、位置的热环境差异,并着重对比了处于迎风建筑和下风向建筑中室外机散热的差异。研究表明,空调室外机的运行效能受建筑群内风场环境的影响较大。正面风向下,风速越大,室外机效率越差;下风向建筑B处室外机运行时的效率更差。后面风向下,处于下风向建筑A处室外机的平均进风温度相对来说更高。

住宅辐射空调系统新风量探讨

分析了国内外住宅新风标准与新风量计算方法,通过案例对比分析了不同计算方法及其结果,明确了住宅辐射空调系统最小新风量计算适用方法和工程推荐值,提出了住宅辐射空调新风系统节能路径。

室外机防护格栅对空调夏季运行能效影响的实验研究

人们通常将注意力集中在空调设备的额定能效,却较少关注室外机安装方式对空调系统实际运行能效的影响。实际上,空调室外机的防护格栅形式在很大程度上会影响整个系统的能效。因此,对防护格栅的设计和安装进行有效改进,以降低空调的能耗,变得尤为重要。为了解决传统空调室外机防护格栅通风换气能力差的问题,设计了一种高效节能通风防护格栅,并通过实验验证了其在提升系统能效比和节能性方面的成效。结果显示,在夏季平均气温维持在35℃的条件下,相较于传统防护格栅,这种节能防护格栅能够将能耗降低33%,系统制冷能效比提高59%。实验表明,本文所设计的防护格栅对于改善凹槽式安装的空调室外机系统性能具备显著效果。

老年健康导向下的住区室外活动空间热环境研究——以合肥西园新村为例

随着全球气候变化和人口老龄化进程加速,老年人作为最容易受到气温环境负面影响的群体之一,社区室外活动空间恶劣的微气候已经严重影响老年居民健康及室外活动的开展。针对日益严峻的老年健康问题,本文通过梳理相关文献,厘清空间热环境和老年健康的关系,对老年健康温度阈值进行定量研究。以合肥住区室外活动空间热环境为研究对象,将提升老年健康为目标,采用ENVI-met软件对社区热环境现状进行量化分析,科学评估活动空间的热环境品质,并通过健康温度阈值筛选出更适合老年居民使用的室外活动空间,探讨室外活动空间的选址及优化建议,为住区室外活动空间的选址、设计和改造提供理论依据。

热泵型新风环境控制一体机PMV控制仿真研究

为满足个性化热舒适的控制需求,运用XGBoost算法建立个性化热舒适预测模型;基于TRNSYS软件平台,建立热泵环控机组PMV控制模型;提出热泵环控机组的调控策略,并用偏冷和偏热调节两个案例进行了验证。结果显示:通过特征参数分析选取空气温度、空气风速作为控制变量,以PMV为被控参数,将基于XGBoost算法的个性化热舒适模型应用到热泵环控机组中,能够满足用户个性化的室内热舒适需求。

辽宁省某生活垃圾焚烧发电厂暖通设计

重点介绍了垃圾池间和卸料大厅的热风供暖措施,结合项目特点介绍了渣池间通风、新风系统和蓄电池室空调通风的设计,并探讨了利用冷却水余热的溴化锂热泵供热系统的经济性及可行性。结果表明,垃圾池间暖风系统采用多管淹埋式送风装置能自动适应垃圾堆料面变化,达到最佳的热风供暖效果。锅炉风机采用多支路防臭抽风系统,能有效地防止垃圾池间和卸料大厅的臭气扩散,又能减少大量抽风造成的加热量浪费。冬季从锅炉间补充热风可改善渣池间的能见度和环境温度,且不影响锅炉间供暖效果。房间及走道需要设计合理正压值,新风取风口和污染源须保持足够距离,可减轻臭气的影响。蓄电池室空调通风设计时需要充分考虑防爆及温湿度工况。溴化锂热泵方案的经济性分析需要考虑供热量、冷却水温度对汽轮机发电效率的影响。

分体空调室外机废弃风能分布特征的实验研究

在我国“双碳”政策的驱动下,可再生能源地有效利用成为备受关注的话题。通过在分体空调室外机上设置不同测量点,测量室外机产生的废弃风能,获得了室外机风能在空间的分布规律曲线及拟合函数。研究表明,室外机产生的风能受测量点与空调外机风扇中心点距离的影响,随该距离的增大呈抛物线的变化规律。其可为有效回收室外机废弃风能提供相对最佳的空间位置,为可再生能源的利用提供新颖的角度。

武汉某研发生产项目空调系统设计与分析

介绍了武汉市某研发生产项目空调系统设计,舒适性空调采用冰蓄冷技术,冷水机组位于蓄冰装置上游,输配水系统为变流量二级泵系统,二级泵分环路设置。数据中心采用水侧自然冷却技术,配置闭式蓄冷罐作为应急冷源,输配水系统为变流量一级泵系统。空调末端划分内外区,采用变风量空调系统,内外区合用1套热回收型新风机组。室外空气湿球温度低于5℃时,开启冷却塔+板式换热器免费供冷,降低系统运行费用。

变风量空调系统的优化控制

从变风量末端装置控制、空调机组送风温度控制、空调机组风机转速控制、空调系统新风量控制4个方面介绍了变风量空调系统的优化控制原理。每个方面都从控制目标、控制对象、控制逻辑明确了各控制环节要做什么、如何做好的关键环节。

渤海湾海上电力动力平台暖通空调系统设计研究

海上电力动力平台上设置有大量高压电气设备间等房间,合理的暖通空调系统设计对于设备的安全稳定运行起到重要作用。以渤海湾某岸电工程海上电力动力平台暖通系统设计为例,阐述了系统设计标准、设计原则和设计方案。实践结果表明,设计原则和设计方案合理可行,可为后续海上电力动力平台暖通空调系统设计提供参考。

深圳地区某近零能耗学校设计探讨

以深圳地区某学校项目为案例,对近零能耗建筑相关技术难点进行了分析论证,并提出多项运维、科普措施:采用分体空调的教室设置集中新风系统;利用EnergyPlus软件进行模拟计算,证实热回收装置在深圳地区不具有经济性,新风系统不设置热回收装置;编制近零能耗建筑运行管理手册和师生个人节能减排行为建议书,并结合课程进行知识科普,倡导师生行为节能。