浦东国际机场变空调供水温度节能运行方案分析

根据离心式制冷机组的性能特征，探讨了制冷机变冷水温度节能运行的可能性，得出了冷水温度、冷水流量与供冷量的关系。针对浦东国际机场的负荷特点和气象条件，给出了分阶段变水温运行的方案。     

不同气候区多地铁站集中供冷负荷特性分析

选取某典型地铁站作为计算依据,首先分析了单个地铁站在不同气候区气象条件下的负荷特性,进而分析了多地铁站集中供冷的负荷特性,提出了影响集中供冷系统能耗的负荷特性指标：集中供冷的峰值负荷、供冷期时间加权平均率。     

上海地区集中供冷能耗测试分析

通过对上海某集中供冷小区夏季工况进行测试，比较制冷机制冷量和用户耗冷量，得出结论，表明由于入住率低，导致制冷机长期低负荷运行，制冷机及其附属设备耗电量大。     

区域供冷供热系统的负荷预测

针对区域供冷供热的特点,提出一种有效的区域负荷预测方法:通过建立几种适用于某一地区的典型建筑DeST负荷计算模型,模拟出不同类型建筑的全年逐时负荷并对数据进行分析处理,得出不同类型建筑的全年峰值负荷与负荷率时间分布,用来指导该地区的区域负荷预测或区域供冷供热系统的研究。     

区域供冷系统能源站冷负荷预测及同时使用系数的确定

该文介绍了规划设计阶段区域供冷系统能源站负荷预测及同时使用系数确定存在的问题。并以重庆市江北嘴区域供冷项目为例,借助鸿业负荷计算软件对各终端建筑的总冷负荷进行逐时计算分析得到其能源站设计总冷负荷为500943.00kW,进而计算出其冷负荷的同时使用系数为0.69。     

区域供冷系统经济供冷距离研究

建立了区域供冷系统经济供冷距离的数学模型,编制了相应的求解程序,并结合一工程实例进行了计算,结果表明:冷负荷密度、二次管网冷水供回水温差均为区域供冷系统经济供冷距离的重要影响因素,但供回水温差的影响更大;当二次管网冷水供回水温差分别为10℃和8℃时,区域供冷系统的经济供冷距离随冷负荷密度的升高而增加;冷负荷密度很小的区域不宜采用区域供冷系统;区域供冷系统二次管网不宜采用5℃以下的冷水供回水温差.     

虹桥机场空调负荷模型研究

通过虹桥机场能源中心供冷运行数据的收集,采取数学方式建立供冷量、温度、湿度三者之间的关系模式,对负荷预测进行初步探讨,通过供冷量的预估可以指导日后的每日的开机策略,优化管理和运行模式,从而实现节能的目标。     

碳中和城市建筑能源系统(3):负荷篇

本文是碳中和城市建筑能源系统系列文章的第三篇。碳中和城市能源系统要实现“两个替代”,即能源生产的可再生能源替代和能源消费的电力替代。因此有2个关键点对负荷分析提出了要求：一是建筑电气化,使得建筑供热供冷负荷与电力负荷更紧密地结合在一起。二是可再生能源利用的规模化,使得电力系统从原先只应对需求侧的变动负荷,变为要应对需求侧和供应侧2个方面的变动负荷;而建筑成为电网灵活性的最主要的提供者。本文总结了在这种形势下的电力负荷和冷热负荷分析的特点,阐述了电力负荷分析与建筑供热供冷负荷分析技术路径的异同。重点介绍了在建筑能耗限额背景下供热供冷负荷的反推方法,以及其重要参数“当量满负荷小时数”的概念和生成方法。最后介绍了为电网提供灵活性的供热供冷负荷预测的技术路径。     

气候变化对办公建筑极端负荷的影响

利用TRNSYS能耗模拟软件模拟了1961—2009年天津市典型办公建筑的供暖和供冷负荷,结合同期气象资料,着重分析了建筑极端负荷与气候变化的关系。结果表明,1961—2009年办公建筑供暖极端负荷日数极显著下降,而供冷极端负荷日数无显著变化;供暖期和空调期过渡月份的极端负荷日数出现较少,供暖期极端负荷占总负荷的比例呈减小趋势,在空调期的变化不大;供暖极端负荷日数主要受气温的影响,而供冷极端负荷日数除受气温影响外,还与相对湿度的变化有关。     

区域供冷系统最佳供冷面积探讨

对于容量已确定的热电厂，为实现热电冷联供，可以根据集中供冷区域空调负荷的特点，利用总能耗最小的原则，确定区域供冷系统最佳供冷面积，以便充分利用区域供冷系统优势，实现节能目的。     

Part load performance of air-cooled centrifugal chillers with variable speed condenser fan control

Air-cooled centrifugal chillers are commonly used in commercial buildings but their performance analysis is lacking. This paper investigates the part load performance of the chillers via a thermodynamic model. The model was validated using a wide range of operating data from an existing chiller with specific settings of outdoor temperature and condensing pressure in controlling the condensing temperature. The validated model was developed specifically to ascertain the maximum coefficient of performance of chiller (COP) together with the strategy for optimizing the condensing temperature under various operating conditions. It is found that the highest COP occurs at a part load ratio (PLR) of 0.71–0.84, depending on the outdoor temperature and the control of condensing temperature, rather than at full load. Yet the chillers operating at such part load conditions will cause extra energy used for the early staging of chilled water pumps. To minimize the overall chiller plant energy consumption, it is still preferable to implement chiller sequencing based on the full load condition than on the aforementioned PLRs. The results of this paper present criteria for implementing low-energy strategies for operating air-cooled chillers satisfying a given building cooling load profile.     

The impact of using chilled water storage systems on the performance of air cooled chillers in Kuwait

In the air conditioning (AC) industry chilled water storage (CWS) systems are one form of cool thermal storage technology that can be used to time shift the electrical load of the system from the peak day periods to off peak night time periods. In this paper the data for the actual exported and generated electrical energy obtained for the power stations in Kuwait has been used to estimate the electrical energy consumption and the peak electrical load of AC systems. Since the chiller in an air cooled AC system represent more than 75% of the total electrical power consumed by an AC system during the peak demand period, the impact of using CWS systems with alternative operating strategies including partial (load levelling), partial (demand limiting) and full load has been investigated. In our conclusions we estimate that approximately 45% of the total annual exported electrical energy is consumed solely by AC systems as a result of the very high ambient temperatures occurring between March and October. Furthermore, it is estimated AC systems represent about 62% of the peak electrical load. The results demonstrate that CWS can reduce the peak electrical load of a chiller in an air cooled AC system by up to 100% and reduce the nominal chiller size by up to 33% depending upon the operating strategy adopted. This is achieved with only a 4% increase in power consumption of the chiller for all CWS strategies except for full storage where the energy consumption actually decreases by approximately 4%.     

Low-energy design for air-cooled chiller plants in air-conditioned buildings

Chillers are widely used for cooling buildings in the subtropical regions at the expense of considerable energy. This paper discusses how the number and size of air-cooled chillers in a chiller plant should be designed to improve their energy performance. Using an experimentally verified chiller model, four design options were studied for a chiller plant handling the cooling load profile of an office building. Using chillers of different sizes is desirable to increase the number of steps of total cooling capacity. This enables the chillers to operate frequently at or near full load to save chiller power. Pumping energy can also be saved because of the improved control of chilled water flow whereby the chilled water supplied by the staged chillers can match with that required by air side equipment for most of the operating time. It is estimated that the annual electricity consumption of chiller plants could drop by 9.4% with the use of unequally sized chillers. The findings of this research will offer guidance on how to select chillers of different sizes for a low-energy chiller plant.     

一种地铁空调冷站设备的监控方式

探讨了地铁空调负荷变化大、时间滞后大等特点，介绍了一种地铁空调冷站设备的监控方式。这种监控方式能够帮助实现冷水机组的运行台数与空调负荷相匹配，同时实现机组最优启停时间控制。     

Optimum load sharing strategy for multiple-chiller systems serving air-conditioned buildings

Many central cooling systems in air-conditioned buildings have multiple chillers to meet various cooling load requirements. This paper further develops optimum load sharing strategies for the chillers in order to maximize their aggregate coefficient of performance (COP). Based on the part load performance curves of air-cooled screw chillers, it is ascertained that for two equally sized chillers operating, one should carry a full load and the other should be partially loaded to meet the system load. When two chillers of different sizes are running, the larger chiller should be fully loaded and the smaller chiller should operate at part load in order that their combined capacity satisfies the system load. Such an uneven load sharing strategy for achieving maximum COP is independent of ambient conditions and the control of condensing temperature. The variable primary flow of chilled water should be applied to chillers in order to implement the strategy. The results of this paper are useful in developing low-energy chiller plants.     

Economic benefits of optimal control for water-cooled chiller systems serving hotels in a subtropical climate

A water-cooled chiller system in an air-conditioned hotel can take up about one-quarter of the total electricity consumption and considerable amounts of water in the heat rejection process. This paper evaluates operating cost savings of a chiller system integrated with optimal control of cooling towers and condenser water pumps. A sophisticated chiller system model was used to ascertain how different control methods influence the annual electricity and water consumption of chillers operating for the cooling load profile of a reference hotel. It is estimated that applying load-based speed control to the cooling tower fans and condenser water pumps could reduce the annual system electricity use by 8.6% and operating cost by 9.9% relative to the equivalent system using constant speed fans and pumps with a fixed set point of 29.4 °C for cooling water temperature control. The ways to implement this advanced control for system optimization are discussed.     

Energy signatures for assessing the energy performance of chillers

This paper investigates how energy signatures can be used as an alternative to an energy use intensity (describing the annual electricity consumption of chillers in kWh per unit floor area of a building in m²) to assess the energy performance of chillers with various design options and operating strategies. An energy signature is a best-fit straight line relating chiller power to a climatic index when chillers operate for a building cooling load profile. Sixteen combinations of four design options and four operating strategies for chillers serving a hypothetical hotel are studied by simulation. For each combination, an energy signature for the chillers is determined. The slope and intercept of the energy signature can be used to accurately predict the annual electricity consumption of the chillers and to evaluate the extent to which this consumption can drop when chiller efficiency is improved. It is desirable to develop reference energy signatures in relation to different characteristics of building cooling load as a yardstick for the minimum requirement of chiller performance. With this yardstick, the effectiveness of energy efficient measures in the operation of chillers could be identified.     

海南某数据中心空调系统设计

结合项目当地具体气候条件,综合对比多种空调系统方案,从节能效果、初投资、运行费用等各方面计算分析,找到适合本项目的 空调系统节能设计.空调设计从系统架构特点出发,利用备用机组的制冷能力,结合磁悬浮机组部分负荷效率高的优点,实际运行时冷水机组全部运行,主机负载率为70％～80％,磁悬浮主机的COP可达15以上,配合冷却塔...     

冰蓄冷系统中主机制冷量的确定

通过对三种不同配置的冰蓄冷系统的逐时负荷和各节点载冷剂温度变化的详细分析,指出根据目前常用的公式计算出的主机制冷量在很多场合不能满足实际负荷要求。通过对这几种系统控制性能的初步比较得出主机上游且融冰优先的串联系统最有效,同时指出配有基载主机的蓄冰系统的负荷分配设计中需要注意的问题。     

对IPLV的学习和研究(2):应用讨论

指出现行国家标准GB 50189—2005对IPLV计算和测试公式中A,B,C,D的定义是100%,75%,50%,25%负荷率时的性能系数,而不是将整个负荷以100%,75%,50%,25%为中心划分为4个区域所对应的负荷区间的性能系数。采用该式计算具体项目全年运行工况下的冷负荷和全年运行能耗的研究思路忽视了标准所设定的4个特定负荷点性能系数的特定条件,在理论上是不严谨的。现行国家标准对冷水机组性能的评价同时采用名义工况性能系数COP和综合部分负荷性能系数IPLV两个指标,二者缺一不可。