中央空调系统节能改造实践

结合现有建筑的中央空调系统的运行状况及空调区环境参数指标要求,对其进行节能改造。通过自动控制各机组设备优化运行及根据建筑负荷变化特性对系统实施动态调节,提高了能源利用效率,降低了空调系统运行能耗。该方案将中央空调系统节能技术与互联网技术结合,提高了系统管理效率,为既有设备的节能改造提供思路与参考。     

某网球中心中央空调系统节能诊断

本文从空调末端设备设计与使用现状对比、末端设备选型、空调水系统现场检测和运行管理水平几方面对某网球中心中央空调系统进行了节能诊断,并根据项目特点提出了可行性节能改造方案。作者希望该论文对我国既有建筑中央空调系统的节能诊断和改造有一定的参考价值。     

武汉中央空调节能对策的探讨

中央空调系统节能,是指在保证建筑物使用功能和满足室内热环境及空气质量的条件下,通过提高建筑围护结构保温隔热性能和中央空调系统的运行效率,使建筑物中央空调能耗降低到规定水平。中央空调系统节能的内容主要包括建筑围护结构节能和中央空调系统节能两个方面。　　武汉市的建筑热环境是冬冷夏热,空调用电负荷大,若以每年最低月电力消耗量为非空调消耗量,2000年最热月的空调运行耗电量达到了53%(以城镇商业、居民生活和非居民非空调用电为基数),2001年达到了54%,2000年空调用电量占全市用电量的10.4%。由此本文认为,探讨武汉市中央空调节…     

节能在舒适性中央空调系统中的应用

本文针对舒适性中央空调系统在节能方面的应用,通过对建筑围护结构的设计、空调系统设计及运行管理的分析,提出了在设计方面应采取的措施。     

商场建筑中央空调系统提前启停运行策略研究

本文以某商场建筑中央空调系统为研究对象,利用TRNSYS建立空调系统仿真平台。利用该仿真平台,研究了该商场建筑中央空调系统在不同提前启/停时间条件下的室内温度达标率,指出了影响商场建筑中央空调系统提前启/停机时间的主要因素,并分别给出了提前启/停机时间随室内温度和室外温度变化的规律。在保证室温达到规定温度的前提下,对不同提前启/停运行方案的节能性进行了模拟分析,提出了空调系统按实际情况确定合理的提前开机和提前停机时间的运行策略。     

中央空调的节能措施及维护保养

随着人们生活水平的提高,中央空调在商场、医院等建筑内的应用越来越广泛,尤其在大型高层建筑中发挥了重要作用。为了减少空调运行成本、提高空调的运行稳定性以及延长空调使用寿命,必须要对中央空调采用有效的节能措施,并加强日常维护。本文就中央空调的节能措施及维护保养进行简单探讨。     

大型医院建筑空调系统节能改造分析与实践

大型医院建筑的主要能耗为空调能耗,结合中南大学湘雅二医院外科楼A座及内科楼原中央空调系统运行情况及特点,提出空调系统"大小分离、按需耗能"的节能技术改造方案,将舒适空调与净化空调进行系统分离,分别满足其需求.改造结果表明,中央空调系统实现高效运行,整体平均耗电量降低25％,可有效减少能源消耗,达到节能改造目的.     

中央空调节能方法研究

在能源日益短缺的今天,节能已经成为整个社会各行各业研究的热点问题.民用、公用及商用建筑中央空调的能耗在建筑能耗中占很大比例,所以对它的研究对于节能意义重大.从建筑物的围护结构、空调的冷热源、空调水系统以及管理等方面,提出了中央空调节能的具体措施和方法.     

惠安广电空调系统设计

本文阐述了福建省泉州市惠安县广播电视大楼的空调系统设计,对于这类建筑的特殊功能和工作环境的特殊性,结合各项经济技术指标等诸多因素,根据各种空调系统运行环境、特点等方面的选择与比较,最终采用了数码涡旋中央空调。本文着重分析了结合建筑特殊功能的合理设计、选用合适的空调系统、因地制宜地布置室内外机组、合理系统分区、室内气流组织设计、新风处理方式等方面的内容。将数码空调系统与此类特殊建筑紧密联系在一起,既保证了建筑功能的完整性,又将数码涡旋空调系统潜在优势发挥得淋漓尽致。     

优山美地别墅中央空调地源热泵系统设计

随着人民生活水平的不断提高，住宅建筑得到迅速发展，人们对居室舒适性，空气品质和自动控制的要求也越来越高。本文为优山美地别墅中央空调地源热泵系统设计，内容包括方案和控制系统的选择，空调末端设备、末端附属设备的选型，并进行施工图的绘制。 本设计从节能和环保角度出发，综合考虑建筑结构、使用要求、环境条件，在系统的选择、设备的选配及系统运行控制等方面采取节能措施。使系统在各种工况下均能高效节能运行。     

Performance analysis of supply and return fans for HVAC systems under different operating strategies of economizer dampers

HVAC systems and associated equipment consume a relatively large fraction of total building energy consumption, a significant portion of which is attributed to fan operation. The operation of economizer dampers when installed can cause high energy consumption in fans if they are not functioning in proper and optimal manner. This will mainly be due to the potential high pressure drops through those dampers and associated high total pressures that should be developed by supply and/or return fans. It is then necessary to ensure that a proper strategy to operate optimally the economizer dampers is implemented with minimum fan energy use. The paper examines several operation strategies of the economizer dampers and investigates their effects on the performance of both the supply and return fans in HVAC system. It also discusses a new operating strategy for economizer dampers that can lead to lower fan energy use. The strategies are evaluated by simulations for a typically existing HVAC system. Several factors such as the building locations, system characteristics, resistance in the duct where the dampers are installed, supply air temperature and economizer control, and minimum ventilation requirements are also considered during the evaluations. The results show that the way of the economizer dampers been controlled has a significant effect on fan performance and its energy use. The proposed strategy if properly implemented can provide fan energy saving in the range of 5-30%, depending mainly on the number of hours when the system operates in the free cooling mode, damper characteristics, and minimum outdoor air.     

Envelope retrofit and air-conditioning operational strategies for reduced energy consumption in mosques in hot climates

Thermal performance of buildings is mainly determined by their thermo-physical and operational characteristics as well as the prevailing climatic conditions. Mosques which represent a unique type of building in terms of construction and operation can be major consumers of cooling energy, particularly in hot climates, if not properly designed and operated. In this study, energy modeling and simulation is utilized to identify potential energy savings due to envelope retrofitting measures and air-conditioning (A/C) operational strategies while maintaining acceptable thermal conditions. Results revealed a good potential for energy reductions when proper thermal retrofitting and operational strategies are employed. As much as 26% reduction in annual cooling energy is obtained when applying roof and wall insulation and reducing air infiltration to 0.5 ACH. By implementing a proper A/C operational strategy and employing system efficiency improvements, the required cooling energy can be reduced by around 36%. The total reduction in cooling energy consumption due to combined A/C system and envelope retrofit measures can be as much as 48%. A number of recommendations pertaining to mosque design, retrofitting and A/C operational strategies are derived. These are expected to be of great use to mosque designers and operators worldwide, but particularly in hot climates.     

Online fault detection and diagnosis in VAV air handling unit by RARX modeling

Assimilation of cost-effective fault detection and diagnosis (FDD) technique in building management system can save enormous amount of energy and material. In this paper, recursive autoregressive exogenous algorithm is used to develop dynamic FDD model for variable air volume (VAV) air handling units. A methodology, based upon frequency response of the model is evolved for automatic fault detection and diagnosis. Results are validated with data obtained from a real building after introducing artificial faults. Robustness of the method is further established against sensor errors arising out of faulty bias during long term use or lack of proper commissioning. It is concluded that the method is quite robust and can detect and diagnose several types of faults. A short and simple method is also included in this paper to detect the faults of VAV units operating in the same zone by comparing their behavior. The new method, which requires very small amount of computation time, was tested with the aforementioned database and shows satisfactory results.     

Heating system performance estimation using optimization tool and BEMS data

Causes and effects of a few real faults in a hydronic heating system are explained in this paper. Since building energy management system (BEMS) has to be utilized in fault detection and diagnosis (FDD), practical explanations of faults and their related effects are important to building caretakers. A simple heat balance model is used in this study. The model is calibrated using the optimization tool. Site data from the BEMS of a real building are calibrated against the model. Desired and real data are compared, so that the effects of the following faults are analyzed: faults in an outdoor air temperature sensor, fault in the time schedule, and a water flow imbalance problem. This paper presents an overview of the real causes of the faults and their effects both on the energy consumption and on the indoor air temperature. In addition, simple instructions for the building caretakers for fault detection in the hydronic heating systems are given.     

离心式制冷机系统传感器故障诊断的试验研究

传感器的可靠性及准确性对制冷机系统的可靠控制和系统的最优运行起着至关重要的作用。同时,传感器的读数也是进行部件故障诊断的基础。本文提出了基于主元分析法的制冷机传感器故障诊断方法,该方法的主元分析模型由离心式制冷机系统中的相关测量变量在正常条件下的观测样本构成。这一方法利用这些变量在正常条件下的相关性来对传感器的测量观测值进行故障检测与诊断及测量重构,并分别用Q-统计及Q-分布图来对传感器故障进行检测及诊断。本文利用实验室离心式制冷机的试验数据对这一基于主元分析法的传感器故障诊断方法进行了验证。     

Development and validation of online models with parameter estimation for a building zone with VAV system

The energy consumption by building heating, ventilating, and air conditioning (HVAC) systems has evoked increasing attention to promote energy efficient control and operation of HVAC systems. Application of advanced control and operation strategies requires robust online system models. In this study, online models with parameter estimation for a building zone with a variable air volume system, which is one of the most common HVAC systems, are developed and validated using experimental data. Building zone temperature and zone entering air flow are modeled based on physical rules and only the measurements that are commonly available in a commercial building are used. Various validation experiments were performed using a real-building test facility to examine the prediction accuracies for system outputs. Using the online system models with parameter estimation, the prediction errors for all validation experiments are less than 0.28 °C for temperature outputs, and less than 84.9 m³/h for air flow outputs. The online models can be further used for local and supervisory control, as well as fault detection applications.     

基于BAS的空调系统过程监测与故障诊断

提出了基于BAS的空调系统过程监测与故障诊断模式，阐述用主成分分析法进行故障诊断的过程，并用其进行空调系统的传感器故障诊断。结果表明，主成分分析法具有很好的故障检测、故障识别和故障重构能力，还表明，故障诊断与BAS相结合是可行的。     

基于冷水量变化的冷水机组性能测试与故障诊断

研究了定流量/变温差和变流量/定温差条件下冷水量变化对机组性能的影响。结果表明:大型冷水机组蒸发器侧冷水大范围变流量不会影响系统的稳定性;在一定范围内冷水机组制冷量与冷水流量呈线性变化,系统的性能系数COP基本保持稳定,这为冷水泵的节能运行提供了良好的依据;蒸发器盘管中冷水流量较大时,允许的冷水流速变化范围可以适当增加;冷水量调节的极限速度为10.1%/min,否则会造成冷水机组运行不安全;蒸发器冷水流量变化引起的冷水机组性能变化可作为故障诊断的判断依据。     

A rule-based fault detection method for air handling units

Air handling unit performance assessment rules (APAR) is a fault detection tool that uses a set of expert rules derived from mass and energy balances to detect faults in air handling units (AHUs). Control signals are used to determine the mode of operation of the AHU. A subset of the expert rules which correspond to that mode of operation are then evaluated to determine whether a fault exists. APAR is computationally simple enough that it can be embedded in commercial building automation and control systems and relies only upon the sensor data and control signals that are commonly available in these systems. APAR was tested using data sets collected from a “hardware-in-the-loop” emulator and from several field sites. APAR was also embedded in commercial AHU controllers and tested in the emulator.     

Online fault detection and robust control of condenser cooling water systems in building central chiller plants

This paper presents a robust strategy for online fault detection and optimal control of condenser cooling water systems. The optimal control strategy is formulated using a model-based approach, in which simplified models and a hybrid quick search (HQS) method are used to optimize the performance of the overall system by changing the settings of the local process controllers. A system level online fault detection scheme is embedded into the control system and used to monitor whether the system operates in a healthy condition. The faults considered are mainly the component performance degradations. When a fault is detected, the control system will be reconstructed to regain the control through using robust schemes. The performance of the proposed strategy is tested and evaluated against on a simulated virtual system representing the actual condenser cooling water system in a super high-rise building. The results show that the fault detection scheme is effective in identifying system performance degradations and the fault-tolerant control strategy with online fault detection and optimal control can enhance the overall system performance significantly when the operation of condenser cooling water systems suffers from performance degradations, as compared to that using optimal control only.