基于模型的离心式制冷机组系统优化控制策略研究

本文提出了基于模型的离心式制冷机组系统台数优化控制策略。该优化控制策略充分利用系统日常调试与机组自身提供的可靠数据,采用简化模型来评估单台机的最大制冷量、计算单台机的瞬时制冷量,并预测一定负荷下不同台数机组运行时的系统总电功率,寻求制冷机台数的优化组合,以使得制冷机组系统的性能系数最大化。     

制冷站冷却塔节能控制策略优化探讨

由于冷却水温度对制冷机组的COP(性能系数)值影响很大,因此,可以利用新型冷却塔控制策略降低冷却水温度,从而提高制冷机组的工作效率。新型冷却塔控制策略的主要内容是:依据冷却水温度、环境参数控制冷却塔运行台数和风机频率,充分利用室外良好的气候因素降低冷却水温度,提高制冷机组的效率,实现整个制冷机房的高效运行。     

太阳能吸附式空调系统的运行优化及试验研究

介绍了上海生态建筑示范楼太阳能吸附式空调系统的设计。根据吸附式制冷机组的运行特性,利用方差分析的方法,对两台吸附式制冷机组的并联运行模式进行了优化。在此基础上,研究了夏季典型工况下太阳能吸附式空调系统的运行特性,包括太阳能集热器阵列、蓄热水箱、吸附式制冷机组的水温变化规律以及系统制冷量的变化规律。     

太阳能地板辐射供暖制冷系统模型仿真

近年来,我国北方地区新建住宅的采暖系统多数采用地板辐射供暖技术,而制冷系统仍采用传统的空调制冷技术,有必要对地板辐射制冷技术的应用进行研究,为此,针对一套实验用太阳房,搭建了太阳能地板辐射供暖制冷系统.通过计算确定了集热器面积、蓄热水箱体积、吸收式制冷机组的制冷量.利用TRNSYS仿真平台建立了系统仿真模型,并对控制策略进行了验证.仿真结果表明,该系统能有效地利用太阳能保持冬季室温18℃左右、夏季26℃左右的舒适温度.     

地铁车站水冷空调机组性能研究

通过正交试验测试了水冷磁悬浮变风量空调机组非标准工况的性能,采用极差分析法及指标-因素图明确了影响该空调机组制冷量、机组EER等参数的主要因素,并对此进行了性能分析。为针对地铁车站公共区采用直膨式空调系统方案建立相关的数学模型、制定节能措施和全年优化运行控制策略,提供了实测数据支撑。     

带蓄冷装置区域供冷系统负荷预测与优化控制

针对某带蓄冷装置的区域供冷系统,基于时间序列对负荷进行预测.以制冷机组日运行成本最小化为目标,建立能源站优化控制模型,分析了50％、75％、100％设计冷负荷条件下的优化控制策略.     

蓄冷空调系统蓄冷实际过程对系统设计影响的分析

本文就蓄冷空调系统夜间蓄冷过程进行了分析计算。计算表明,蓄冷空调系统夜间蓄冷时间比蓄冷器的理论蓄冷时间要长,与蓄冷器性能、冷冻水流量、制冷机组的制冷量有直接关系。设计时,必须充分考虑蓄冷系统启动时的温度对蓄冷时间的影响,同时保证制冷机组的制冷量和冷冻水流量要与蓄冷器性能匹配。     

基于鲁棒性分析的制冷机组序列控制优化设计方法

合理的序列控制是优化中央空调制冷机组运行能效并保证建筑热舒适性的主要措施。然而,在实际应用中,制冷机组的序列控制会受到不确定性因素的影响而无法合理有效地进行机组切换,并且不同控制策略会随着制冷机组本身的不确定性情况体现出不同的可靠性和鲁棒性。因此,提供一种基于鲁棒性分析的制冷机组序列控制策略优化设计方法。该方法利用机组运行数据建立简化的制冷机组数值平台,对备选的序列控制策略进行鲁棒分析,并通过多准则决策方法选出适合于该制冷机组的序列控制策略。分析表明,该方法可以根据冷机本身的不确定性情况,简便地选择出合适的序列控制策略,可有效提高制冷机组序列控制的可靠性和鲁棒性。     

大容量多联机空调系统的运行特性分析

利用多联机空调(MSAC)系统仿真平台,以制冷工况下室内机容量连续调节的多联机空调系统为例,探讨了大容量多联机系统的稳态运行特性。结果表明,多联机空调系统随连接管长度的增加,其制冷量有较大的衰减,且制冷能效比COPc的性能域宽度逐渐增大;对于单模块室外机组多联机空调系统而言,采用多台压缩机时,其部分负荷下的COPc优于单台压缩机构成的系统;由多个模块室外机组并联拼装构成的多联机空调系统,随室外机组数量的增加,其COPc逐渐降低,故并联的模块室外机组数量不宜太多,以免削弱多联机系统部分负荷率时的高能效比优势。     

基于TRNSYS空调水系统能耗预测应用研究

基于工程实例,通过前期调研及能耗诊断,更换原热水型溴化锂制冷机组为电压缩式制冷机组,更换原低效水泵、冷却塔为高效水泵、冷却塔,对冷水机组运行策略、空调水系统控制策略进行优化设计.利用TRNSYS结合优化控制策略对改造后制冷机房水系统能耗进行预测.经改造,该项目年节能量约213.04tce,节能效果显著.     

建筑环境设计模拟分析软件DeST第9讲冷热源与水系统模拟分析(上)

冷热源系统是整个集中空调系统的核心，完全决定了系统能否保障用户的冷热需求，是投资和能源消耗的主要部分。因此冷热源的选择和运行方式直接关系到空调系统的运行效果，并影响到空调系统的运行能耗的大小。综述了目前模拟计算中的制冷设备的各种建模方法，并结合建筑能耗模拟计算的特点，详细阐述了DeST模拟软件中冷源和水系统模拟过程中所用到的制冷设备半经验模型以及冷源模拟分析方法，为冷热源和水系统的全工况优化运行设计计算奠定了基础。     

Chiller sequencing control with enhanced robustness for energy efficient operation

This paper presents a strategy for improving the reliability and the energy efficiency of chiller sequencing control based on the total cooling load measurement of centralized multiple centrifugal chiller plants. The improvement is achieved as follows. Firstly, a fused measurement of building cooling load is used to replace the direct/indirect measurement. Secondly, the maximum cooling capacity of individual chillers is computed online using a simplified centrifugal chiller model. Thirdly, the online computed maximum cooling capacity is calibrated according to the quality of the fused measurement in order to deal with the possible misbehaviours in measurement instruments. A simplified model for computing the maximum cooling capacity is developed and validated using field data. The performance of the proposed chiller sequencing control strategy is tested and compared with a conventional chiller sequencing control algorithm. Test results are presented showing that the proposed strategy can effectively improve the reliability of chiller sequencing control and reduce the energy consumption of chiller plants.     

对变频离心式冷水机组全年节电的探讨

介绍了变频离心式冷水机组节能的原理及适用条件。基于冷水机组的全年耗电量是冷水机组在不同运行时段内的机组能效、机组负荷与运行时间乘积之和,分析了1台变频离心式冷水机组在单台和多台机组中应用的节电效果。     

An integrated model for the design of air-cooled chiller plants for commercial buildings

Cooling load calculation is the first step in designing the air-conditioning system of a building. The calculated cooling capacity with appropriate buffer is then used to select the number and size of chillers in the system. N + 1 is a common formula used by designers to size the chiller plants in Hong Kong buildings, where N is the actual number of chillers required and 1 is a redundant chiller provided to ensure reliability. This paper reviews the problem of excess capacity and discusses the risk exposure of chiller systems without redundant chillers. The cooling load profiles of the chiller plants of four medium-sized commercial buildings in Hong Kong are reviewed. The risk exposure of chiller systems without redundant chillers can be minimized by applying risk-based preventive maintenance. The just-in-demand design reduces capital cost of the building and frees up funds for continuous energy measurement and improving the energy efficiency of chiller plant systems. This paper presents a model for designing chiller plants that improves the energy efficiency of the plant in a cost effective and thoughtful manner. It is designed with consideration of the life cycle of the plant and real-time continuous commissioning, monitoring, measurement, comparison and execution for better energy management.     

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.     

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。     

变频制冷系统的应用探讨

介绍变频制冷系统的节能原理及适用条件.基于不同冷冻水系统,不同类型制冷机组在不同工况下的能效、耗电量,分析了一次泵变流量冷冻水系统及变频离心式冷水机组在实际应用中的节能效果.     

Energy performance of a cooling plant system using the inverter chiller for industrial building

The purpose of this paper is to clarify energy performance of the cooling plant system in the industrial building using actual measured operating data and numerical simulation analysis. One aspect of industrial buildings is that they have large energy consumption for manufacturing and air-conditioning compared with office and commercial buildings. Some examples of high-efficiency technologies installed in this particular cooling plant system are inverter chillers, integrated cooling towers and a free-cooling system. The inverter chiller which has been put on the market recently is state-of-the-art technology. The maximum COP of the inverter chiller reaches about 18 under certain conditions and integrated cooling towers make lower temperature cooling water as the whole capacity is large. Actual operating data indicates satisfied values for chiller and system COP during the running period and the simulation results show that the cooling plant system can cut down annual electric power consumption by about 48% compared with conventional cooling system.     

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.