Optimization of air-conditioning system operating strategies for hot and humid climates

This paper describes research into the optimal operation of building heating, ventilation, and air-conditioning (HVAC) systems focusing on both temperature and humidity control. While most previous work on HVAC optimization has been limited to evaluation of conventional temperature-based control systems, this study emphasizes the humidity control issue in meeting both sensible and latent building loads. The analysis is based on a combination of a realistic simulation of a direct expansion (DX) air-conditioning system and a direct-search numerical optimization technique. The simulation models have been validated through comparisons with field data. Optimization was performed on five different system control variables to minimize system power consumption while meeting building loads and maintaining comfort. Indoor temperature and humidity are also optimized within standard comfort constraints. Building loads were modeled using an extended bin method that allows consideration of the interactions between loads and indoor conditions. Results indicate that minimum energy use typically occurs at low airflow rates, with indoor humidity levels below the upper comfort limit. Results also show that coil air bypass and evaporator circuiting control are typically not necessary unless operation would otherwise result in overcooling. The optimization results also translate to relatively simple strategies for system control. Significant savings are demonstrated over conventional control strategies used in packaged DX equipment.     

中央空调海水冷却系统自适应优化控制

在淡水缺乏的香港地区,中央空调系统通常采用海水进行冷却。在能源日益紧张的今天,对空调系统进行优化控制是提高能源效率及节省能源的一个重要途径。本文针对中央空调海水冷却系统提出了根据海水冷却水压力设定值调整的微分自适应优化控制方法实现空调系统能耗最小化,然后进一步对该自适应控制方法进行了基于模拟环境的实验验证。结果表明该方法可以降低系统能耗,提高能源使用效率。     

Energy saving effect prediction and post evaluation of air-conditioning system in public buildings

Accurate energy saving effect evaluation analysis of building energy efficiency retrofit is of benefit to obtain technology optimization and fast return of investment. According to the implement sequence, evaluation methods can be divided into post evaluation and prediction evaluation. The energy saving effect of an air-conditioning system retrofit project was analyzed by these two models respectively. The post evaluation model was built based on the spot test data and a parameter called as Refrigeration Operation Energy saving Effect Ratio (ROEER). The prediction evaluation model was built based on Back-Propagation Artificial Neural Network by the use of MATLAB Neural Network Toolbox. The comparison result between these two kinds of evaluation models match well with each other. These two models can be used to predict and evaluate energy saving effect of air-conditioning system retrofit to further improve the real energy saving effect of building energy efficiency retrofit.     

基于多目标决策法的绿色空调系统评价

依据绿色建筑评价标准,采用多目标决策法中的理想点法与权重法,从全寿命周期统筹考虑建筑功能、节地、节能、节水、室内环境、初投资、经营费、运行管理、环境影响、能源消耗等多个目标,优化选择空调系统.建立了层次模型结构,给出了运行管理、相关专业及室内环境量化指标及权重判断矩阵,通过实例验证了该计算方法的可行性及可靠性.     

京津地区夏季着装行为对办公建筑空调能耗的影响

着装行为通过影响室内空气参数的设定而影响建筑空调能耗。利用能耗模拟软件DeST,计算出该地区典型着装行为下实测运行参数与期望参数对应的建筑空调能耗比推荐标准下能耗分别降低了10.86%和13.16%。而基于典型着装行为的实验热学性能参数下,平均只降低4%,说明由着装热阻关联的主观温度需要按地区着装行为进行修正。提出了控制建筑空调能耗的着装行为调节模型,着装行为节能率εc为负值时节能,为正值时不节能。京津地区办公建筑节能率为0的临界服装热阻为0.563clo,空调系统设计和运行节能的前提是,着装热阻低于临界值。着装行为调节模型为地区着装形式和着装面料提供了量化标准,为精确控制建筑能耗提供了一种方法。     

带有地板辐射的座椅送风空调系统的节能分析

建立了带有地板辐射的座椅送风空调系统的模型，并进行了能耗模拟计算。计算结果表明，与无地板辐射的座椅送风空调系统以及普通的上送风空调系统相比较，该系统具有送风量小，更经济、更节能的特点。     

浅谈中央空调节能问题及对策

针对占建筑能耗主要部分的中央空调在节能设计和节能运行方面目前存在的一些具体问题进行了分析，分别从设计参数选择、负荷计算、空调冷热源、空调机组及末端设备选用和水系统设计运行管理等方面，提出了一些节能措施和方法，供空调与建筑节能技术人员参考。     

生态建筑供热空调系统能源利用经济性分析

探讨了自然能源在生态建筑空调及供暖系统中的应用方式,以上海某生态小区为例,将系统工程中著名的灰色物元分析法引入空调供暖系统设计方案的决策过程,采用与节能和环保相关的经济性评价指标,对不同的冷热源方案进行计算和经济技术比较与分析。研究结果表明,绿色能源应用于生态建筑中具有明显的经济效益、节能效益和环境保护效益。     

Application of an energy management and control system to assess the potential of different control strategies in HVAC systems

The significant and continuous increment in the global electricity consumption is asking for energy saving strategies. Efficient control for heating, ventilation and air-conditioning systems (HVAC) is the most cost-effective way to minimize the use of energy in buildings. In this framework, an energy management and control system (EMCS) has been developed to schedule electricity end-uses in the campus of the Universidad Politécnica de Valencia (UPV), Spain. This paper presents an evaluation performed by using the EMCS of different control strategies for HVAC split systems. It analyzed the effect of different schedules for a common air-conditioning device and demand response strategies are tested in several situations. The economic saving is calculated taking into account the electricity contract clauses. Finally, a test is made for the control of a group of similar devices in order to reduce the maximum peak power in consumption and to obtain a flexible load shape with the HVAC loads. The studies are then extrapolated to a larger system, the whole University campus, for which energy and economic savings are quantified.     

Energy saving through evaporatively cooled condenser air in conventional air-conditioning units

A theoretical study of the feasibility of evaporative cooling of the condenser air of a conventional vapour compression air-conditioning system to upgrade the rating of an air-cooled air-conditioning unit and consequent energy saving in the Delhi climate is presented. A brief review of the heat rejection option in an air-conditioning unit has been given and a theoretical background analysis for evaporative cooling of condenser air has also been presented. For illustration, one specific air-cooled package unit, whose performance characteristics as given by the manufacturers are available, has been used for calculations. Temperature variation data for New Delhi in the months of May and June 1991, obtained from the Meteorological Department, has been used. With the basic data, the upgradation of cooling capacity, power requirement and average energy consumption with and without evaporative cooling of condenser air has been calculated and the reduction in peak load and saving in the average energy consumption was predicted. Typical calculations of the water requirements for pre-cooling of condenser air were also predicted and compared with the corresponding requirements for water-cooled and evaporative condensers. It is concluded that there is an excellent and exciting possibility of reducing energy consumption (and consequent enhanced energy saving) in air-conditioning at national level.     

Research on parametric design method for energy efficiency of green building in architectural scheme phase

Based on a large number of researches and engineering practices both domestic and overseas, it is shown that the building parameters to be determined during scheme phase can exert a great effect on the building energy consumption. In this paper, through a combination of the popular design method of building parameterization at present and the design goal of energy saving during the scheme phase, the author carries out researches on the design methods and tool development which are applicable to parameterization of building energy saving in this stage. In connection with the characteristics of both modeling process of parameterization and energy saving design, and by means of steady calculation as well as simulation, this paper establishes an simplified model to calculate the overall energy consumption of air-conditioning, heating, lighting and equipments, and ultimately gives suggestions on design of scheme for energy saving by optimization with the genetic algorithm (GA). On the basis of the model, a software platform is developed by computer language QT and openGL interface and is oriented to the design users and sets up the MMI (human–computer interaction) software interface for parameterization of building energy saving, which achieves automatic modeling of parameterization and promotes research on practical design cases.     

Adaptive optimal control model for building cooling and heating sources

An adaptive optimal control model for building cooling and heating sources is presented with the aim of achieving global optimization and satisfying the requirements of time and accuracy in HVAC system control. The adaptive optimal control model includes the optimal control model, parameter identification and optimization algorithm. First, the penalty function is constructed to transform constrained optimization problem into unconstrained optimization problem, and then, the fuzzy self-tuning forgetting factor method is developed for parameter identification. In the end, the genetic algorithm (GA) is used to find the optimum values for the discrete and continuous variables. Optimization is applied for the building cooling source system in a publishing house located in Changsha, China. The optimization is expected to reduce the energy consumption of the cooling source system by 7%.     

多元模块式中央空调控制系统研究探讨

控制系统方案是针对武汉某综合体项目中央空调系统设备的节能降耗、科学管理和优化组合运行而设计。多元模块化形式的系统设计,在不同的运行情况下,采用不同模块组合运行,实现了多元化组合调控,加大了系统的可变性。针对中央空调系统的智能管理及能源优化,采用LTUZ能源优化专用控制器和LTUZ智能管理专用控制器,配上远程系统专用智能操作平台,实现中央空调控制的智能管理和能源优化。     

基于CAN总线中央空调变频节能监控系统设计

本文对中央空调现有变频调速节能系统进行分析,提出将CAN总线技术应用于变频节能监控系统,使之真正实现实时分散控制、集中管理,使中央空调系统运行在最佳工况以达到节能效果,并详细介绍了该系统的构成及智能节点的软硬件设计。     

洁净厂房空调系统的特点与节能

世界集成电路产业加速向我国转移.使得洁净厂房空调系统的节能成为关注和研究的焦点问题,也成为各生产商降低生产成本,取得竞争优势的重要手段.对洁净厂房空调系统的特点进行了分析,探讨了其高耗能的原因.并在此基础上,从洁净风量与空调风量分离、减小系统送风量、新风量、优化控制及运行管理等多方面多角度,提出了具体节能的思路、方法和措施.     

高精度空调自控与节能

高精度空调系统主要靠冷热抵消方式实现精度指标,是空气调节系统中能耗最高的系统。在保证控制精度的同时,如何尽可能减少冷热抵消量,是高精度空调系统自动控制的关键。从铂电阻传感器和热敏电阻传感器的阻值/温度变化率大小、三位电动调节阀和模拟量电动调节阀运行时的增量和减量幅度、控制软件PID调节和自适应调节等技术方面进行分析。针对高精度空调系统控制精度的影响,阐述控制系统的硬件组成和软件控制方式在高精度空调系统中的选择方式,以及减少能耗抵消的途径,从而达到节能的目的。     

天津站温湿度独立调节空调系统设计分析

天津火车站改扩建工程项目是2008年北京奥运会重点配套工程,该项目采用了基于溶液调湿技术的温湿度独立调节空调系统。针对该项目,本文详细阐述了温温度独立调节空调系统在各个区域的具体应用形式、特点及其节能效果。采用温湿度独立调节空调系统,该项目每年可节省120万元空调运行费用,并使夏季宅网尖峰负荷减小4400kW。不仅能显著节约空调系统运行费用,还可降低夏季城市电网尖峰负荷,缓解电力紧缺问题,提高热网利用效率,具有重大的经济效益和社会效益。     

户式中央空调节能运行分析

目前实际运行的户式中央空调存在很大的能源浪费现象.本文总结了户式中央空调的形式及特点,从设计、施工安装及运行等方面分析了节能效果不理想的原因;提出了在系统选择、节能设备选型及自动控制过程等方面,户式中央空调节能运行的方案.     

中央空调节能之浅见

从窗墙比的控制、门窗密闭性的设计两方面阐述了围护结构的门窗节能设计方法，分析了中央空调的系统设置，并提出了节能措施，倡导了土壤热源的应用及集中空调的计量收费，以满足节约型社会的需要。     

舒适性空调系统全年节能运行控制研究

介绍了舒适性空调基于负荷分析的全牟多工况分区节能运行方法,提出了一种全年运行的多工况分区策略,并详细分析了各工况区的空气处理过程.该分区运行方法具有分区合理、控制简便、经济节能等特点.