中央空调系统变频节能改造分析

在阐述变频技术节能原理的基础上,结合北京某商贸大厦中央空调系统变频节能改造的实践,进行了效益分析。改造实践证明,对中央空调系统进行冷(热)水循环水泵及冷却水循环水泵变频改造效益明显,改造投资可以在1年左右收回,具有投资前景。     

中央空调水系统的节能改造技术与实践

结合既有建筑的中央空调水系统的设计与运行状况,分析与讨论了水系统的节能改造技术,以及所产生的节能效益、经济效益、系统运行的可靠性与安全性,得出了既有中央空调水系统的节能改造技术有:主机变频、空调泵变频、水蓄冷等;非线性、大滞后的中央空调水系统适合采用智能控制算法。多项工程节能改造表明:中央空调水系统的各项节能率为20.5%~31%,不到2~4年可以回收节能投资,而且空调系统运行正常,室内温湿度满足要求。     

中央空调系统水泵节能改造的试验研究

在两套管路特性基本相同的冷却水系统和两台相同型号的冷却水泵上,分别进行水泵变频调速改造和更换小水泵改造方案的运行试验测试。试验结果表明,两种方案均有明显的节能效果,但是更换小水泵改造方案效果更佳。     

中央空调系统的节能分析

随着能源的紧缺及公用及商用建筑中央空调的高速发展，对中央空调系统的节能改造途径的研究变得非常重要，尤其是中央空调制冷系统在部分负荷下运行状况。本文分别对空调冷热源系统，空调机组及末端设备，水或空气输送系统进行分析，其中特别设计一种含有射流装置的回水循环系统。     

中央空调系统的节能分析

随着能源的紧缺及公用及商用建筑中央空调的高速发展,对中央空调系统的节能改造途径的研究变得非常重要,尤其是中央空调制冷系统在部分负荷下运行状况。本文分别对空调冷热源系统,空调机组及末端设备,水或空气输送系统进行分析,其中特别设计一种含有射流装置的回水循环系统。     

千岛湖海外海大酒店中央空调的节能措施

由浙江海外集团公司投资兴建的千岛湖海外海大酒店是一家按四星级标准兴建的旅游涉外饭店 ,建筑面积 1 870 0ｍ2 ,2 0 0 1年 4月建成投运。1　采取的节能措施在千岛湖海外海大酒店中央空调工程设计论证阶段 ,我们就介入系统设计和设备的选型工作。经过对千岛湖水利地理资源的大量调查 ,对该工程的环境条件作了认真分析 ,采取了以下节能措施 :1 .1　因地制宜选择中央空调主机首先根据千岛湖的实地情况 ,对设计方案进行了合理改进。原设计整套空调机组为 1 0 0万大卡空调螺杆机 2台 ,2 5 0ｔ/ｈ冷却水泵 3台 ,3 0 0ｔ/ｈ冷却塔 2个 ,2 0 0ｔ/…     

中央空调冷却水系统变频节能技术改造

根据一年中气温变化较大,制冷主机冷负荷变化较大,水系统大部分时间在大流量、小温差状态下运行的特点,将冷却水系统与变频器有机结合,形成环状系统,通过空调负荷的变化而改变电源频率,达到通过调节电机转速自动控制冷却水流量的目的。这样,既提高了水泵电机输出效率,又在满足制冷主机对冷却水流量要求的同时,降低了水泵电机轴功率,减少了电能消耗。     

酒店中央空调的节能改造

以浙江义乌海洋大酒店的中央空调系统为例,为了解决冷冻水、冷却水系统长期在大流量、小温差的状态下运行,造成能量极大浪费的情况,介绍了利用变频器、PLC、数模转换模块、温度模块和温度传感器等构成温差闭环自动控制系统,根据负载大小自动调整水泵的运行频率,同时根据冷却水温度的高低,自动切投冷却塔散热风机,以达到节能的经验.     

中央空调系统合同能源管理节能改造

介绍中央空调系统改造优越性,复制性强,合同能源管理优越性、风险控制及走市场化道路。     

简析中央空调系统节能的控制方法与发展趋势——基于江中药业综合制剂大楼中央空调节能改造工程案例

基于江中药业综合制剂大楼中央空调节能改造工程案例,以工程改造的节能技术措施和效果为分析对象,从系统节能的控制方法的角度对中央空调系统节能的发展转变进行剖析。通过调查和数据收集,对目前常用的2种中央空调系统(定流量控制型、变频PID控制型)节能方法的优缺点做了比较分析,展示了各种中央空调系统节能发展转变的特色,提出了中央空调系统节能发展方式、实现高效节能的建议。     

Energy efficiency of small buildings with smart cooling system in the summer

In this paper, a novel cooling control strategy as part of the smart energy system that can balance thermal comfort against building energy consumption by using the sensing and machine programming technology was investigated. For this goal, a general form of a building was coupled by the smart cooling system (SCS) and the consumption of energy with thermal comfort cooling of persons simulated by using the EnergyPlus software and compared with similar buildings without SCS. At the beginning of the research, using the data from a survey in a randomly selected group of hundreds and by analyzing and verifying the results of the specific relationship between the different groups of people in the statistical society, the body mass index (BMI) and their thermal comfort temperature were obtained, and the sample building was modeled using the EnergyPlus software. The result show that if an intelligent ventilation system that can calculate the thermal comfort temperature was used in accordance with the BMI of persons, it can save up to 35% of the cooling load of the building yearly.     

Heating and cooling energy recovery for an HVAC system: Economic analysis for the Italian climate

In this paper the economic analysis of the energy recovery in all‐outdoor‐air HVAC systems for the Italian climate is performed. The energy recovery device considered here is the same for both heating and cooling periods. During the summer season, the energy saving is achieved by evaporative cooling. The performances of the hybrid innovative HVAC system and the traditional system are calculated hour by hour by following the test reference year (TRY) profile. Such analysis is carried out taking into account simultaneously, the trend of some climatic indexes computed in order to (i) better understand the influence of climate on the HVAC system behaviour, (ii) obtain a swift feasibility analysis of the energy recovery system and (iii) perform a rough operating cost estimate of the traditional HVAC system. Copyright © 2001 John Wiley & Sons, Ltd.     

A prototype flash cooling desalination system using cooling water effluents

This paper presents a flash cooling desalination system to reduce thermal pollution and also to produce freshwater using the heat rejected by the process plant into the environment. The prototype plant was erected in an existing coal‐based thermal power plant at North Chennai, India. It consists of an air‐tight barometric sealed flash cooler, positioned at a level at least 10.13 m above the ground level, for the feed seawater to flow under the effect of gravity and to maintain a low pressure. The prototype plant was tested by using a small fraction of the available flows without using any mechanical energy such as motive steam from the power plant. A freshwater production rate of 0.49% of the feed seawater is obtained from the available thermal gradient of 8.5 °C from the condenser reject heat of the power plant, and then the waste water is discharged at near intake concentration of salinity into the sea. The temperature of hot feed seawater is also reduced by 3 °C. The results are used to provide an outline technical specification for larger capacity desalination plant to meet the growing need for freshwater. This is an environment friendly desalination process and consumes no chemicals as it operates at near ambient temperature. This can be effectively utilized for the generation of freshwater, besides protecting the marine ecosystem along the shore, and reducing the load on the cooling tower or eliminating the need for it completely. Copyright © 2012 John Wiley & Sons, Ltd.     

计算机显示器能效标识制度与能效测试

在计算机显示器能效标准和能效测试的基础上,通过分类统计的方法,分析了被测显示器的能效等级和能效指标的分布,讨论了计算机显示器的能效水平和制约因素,说明能效标识制度的实施促进了计算机显示器的节能进程,并对其节能技术创新具有一定的指导意义。     

Energy efficiency of a solar drying system

A solar collector, part of a drying system using solar energy as a heat source, was developed and reported previously and used in product-drying applications. In this study, energy efficiency analyses of the drying system in terms of the collector efficiency were investigated. The results obtained show that the present collector used in this solar drying system is an efficient and effective unit for practical drying applications.     

Energy efficiency of a dynamic glazing system

The reduction of air-conditioning energy consumptions is one of the main indicators to act on when improving the energy efficiency in buildings.In the case of advanced technological buildings, a meaningful contribution to the thermal loads and the energy consumptions reduction could depend on the correct configuration and management of the envelope systems. In recent years, the architectural trend toward highly transparent all-glass buildings presents a unique challenge and opportunity to advance the market for emerging, smart, dynamic window and dimmable daylighting control technologies (Lee et al., 2004).A prototype dynamic glazing system was developed and tested at ITC-CNR; it is aimed at actively responding to the external environmental loads. Both an experimental campaign and analyses by theoretical models were carried out, aimed at evaluating the possible configurations depending on different weather conditions in several possible places. Therefore, the analytical models of the building-plant system were defined by using a dynamic energy simulation software (EnergyPlus).The variables that determine the system performance, also influenced by the boundary conditions, were analysed, such as U- and g-value; they concern both the morphology of the envelope system, such as dimensions, shading and glazing type, gap airflow thickness, in-gap airflow rate, and management, in terms of control algorithm parameters tuning fan and shading systems, as a function of the weather conditions.The configuration able to provide the best performances was finally identified by also assessing such performances, integrating the dynamic system in several building types and under different weather conditions.The dynamic envelope system prototype has become a commercial product with some applications in façade systems, curtain walls and windows.The paper describes the methodological approach to prototype development and the main results obtained, including simulations of possible applications on real buildings.     

Dynamic model of an HVAC system for control analysis

This paper describes a procedure for deriving a dynamic model of an HVAC system that consists of a zone, heating coil, cooling and dehumidifying coil, humidifier, ductwork, fan, and mixing box. In particular, the interest is centered on control strategies to reduce energy consumption and improving the quality of the indoor environment. Indoor temperature and humidity may be maintained at set point values by an air-handling unit using a PID control action. The PID parameters must be carefully tuned to produce less oscillatory responses. The tuning technique, using the Ziegler-Nichols rule, is investigated from a practical viewpoint. Simulation results showing the open loop and the closed loop responses of indoor temperature and humidity ratio are given. The results show that the system is capable of controlling the disturbance efficiently within a small period of time and with less error. The dynamic model can be especially useful for control strategies that require knowledge of the dynamic characteristics of HVAC systems.     

冷水机组低温冷却水系统解决方案分析

通过理论分析与实验方法研究了冷水机组冷却水温度和流量调节的方法。结果表明:采用旁通阀调节冷却水温度,不仅能够保证冷水机组安全、高效稳定运行,且能够有效节约能源;采用冷却水变频方式,可以大量减少能耗,但当环境温度低于10℃时,基本不可用。     

改变补水方式的节能效益和问题

对于热电机组而言，除盐水补充量大，传统补水方式直接补水到除氧器，如改为补水到凝汽器，既有利于溶氧合格，同时节能效果显著。具体分析测算一台C15机组标准工况的节能效益，指出应用中应注意的一些问题。     

盐水冷却塔经济性比较分析

针对北方电厂冷却水供水不足的问题,介绍了盐水冷却塔技术的应用,通过抑制盐水蒸发和减少排污损失可达到节水目的.经对比分析,以600 MW普通水冷机组的冷却量为基准,采用盐水冷却可以每年节约耗水量686.8万吨,节约耗水费用4265.0万元.