离心式制冷机系统优化控制策略研究

提出了基于模型的离心式制冷机系统台数优化控制策略。该优化控制策略充分利用机组系统的日常调试与制冷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、并且预测在一定负荷下不同台数机组运行时系统的总电功率,从而寻求制冷机台数的优化组合使得制冷机组系统性能系数最大化。     

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。     

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。     

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。     

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。     

空气源热泵和地源热泵在滨州海洋馆的复合应用

以滨州海洋馆为例,通过方案比选,选择3台制冷量561 kW/台地源热泵机组和3台制冷量130 kW/台空气源热泵机组的复合能源系统.介绍了该系统的运行原理及策略.与传统的电制冷螺杆机组+燃气热水锅炉的能源方案进行了对比,基于系统投资及运行费用的分析得出,该系统的静态投资回收期为1.49 a,该系统用于海洋馆类建筑具有一...     

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.     

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。     

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。     

Strategy for designing more energy efficient chiller plants serving air-conditioned buildings

In cities located in the subtropical regions, air-cooled chillers are commonly used to cool commercial buildings almost year-round, which accounts for considerable electricity consumption in the long term. This paper explains how a chiller plant should be designed to enable the chillers to operate frequently with maximum performance. Four design options with respect to the number and size of chillers were studied for a chiller plant satisfying the year-round cooling demand of a hotel. For each design option, the annual electricity consumption of chillers and pumps was assessed using a sophisticated chiller model. The assessment showed that an electricity saving of 10.1% can be achieved by installing a chiller plant with six chillers of three different sizes instead of four equally sized chillers. The results of this paper will give engineers and researchers a better idea about how to select chillers of different sizes and how chiller part load performance curves can be used to evaluate improvements in the energy performance of a chiller plant with alternative designs.     

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.     

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.     

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.     

多台不同冷量冷水机组并联节能运行及控制

针对多台不同制冷量冷水机组并联运行的情况,分析了影响系统能耗的各因素,结合实例对比了不同运行方案的能耗,提出了制定节能运行方案的方法。对冷水机组群控的逻辑判据进行分析,从兼顾节能效果和设备使用寿命的角度,提出了将节能运行方案与负荷变化趋势预测相结合的群控策略。     

冷水机组的优化运行

针对冷水温度、冷却水温度及机组启停控制等影响冷水机组运行的主要因素进行了分析，指出适当提高冷水出口温度和(或)降低冷却水出口温度，采用智能调节策略对多台制冷机和水泵的启动顺序进行合理调配，采用BP网络预测最小预热(冷)期和最长提前停机时间对压缩机进行最优启停控制等，都可以降低系统能耗。