螺杆式冷水机组在空调系统中的应用分析

叙述了双螺杆和单螺杆式冷水机组的特点,螺杆式冷水机组的容量调节的方式,以及各种螺杆式机组的适用条件,为空调工程设计中冷水机组的选择提供了一定的借鉴.     

武汉嘉叶宾馆空调冷热源的选择

针对武汉嘉叶宾馆空调扩建工程，文章对螺杆式冷水机组加燃油锅炉，螺杆式冷水机组加蓄热式电热锅炉，直燃型溴化锂吸收式冷温水机组3种类型的冷热源方案进行了技术、经济性分析，作者认为，螺杆式冷水机组加燃油锅炉方案最合适。     

武汉市某酒店节能型空调冷热源方案的选择

根据现有能源结构,结合武汉某宾馆空调冷热源方案的选择,对螺杆式冷水机组加燃气锅炉、螺杆式冷水机组加蓄热式电热锅炉、水源热泵机组3种类型的冷热源方案进行了技术、经济性比较和分析。结果显示:螺杆式冷水机组加燃气锅炉方案初投资最低、运行费用较少,是该酒店最合适的节能型冷热源。     

水冷式制冷机组的性能比较及选型

分析了水冷活塞式、螺杆式和离心式冷水机组的特点，介绍了不同厂家制造的一些代表性的水冷活塞式、螺杆式和离心式冷水机组在名义工况下的性能，总结了他们各自的适用范围和COP值大小，可供实际使用和选型参考。     

大型超市室内环境及空调系统能耗测试分析

深入了解掌握建筑空调系统实际运行状况,有助于准确地分析建筑能耗及空调系统能耗。为此作者选择了上海某一大型超市,通过测试其夏季室内热环境、空调机组、冷水机组水流量等参数,得出超市室内温湿度的分布状况、空调水系统的平衡程度以及冷水机组的能效比,发现实际运行中存在的问题,提出改进超市空调系统运行的方案。     

半封闭活塞式和螺杆式冷水机组性能比较

半封闭活塞式和螺杆式冷机组以其各自鲜明的特点得到了广泛的应用。文章分析了开利半封闭活塞式和螺杆式冷水机组的特点,对比在不同温度和不同冷量下的性能,为实际使用打下基础。     

某宾馆空调冷源方案的比较

介绍了浙江省绍兴市某宾馆改造过程中,对三种空调冷源方案从初始投资和运行费用两方面进行了比较：一是风冷热泵冷水机组（单冷）;二是螺杆式冷水机组;三是溴化锂冷水机组。结果第一种方案最符合要求。     

某住宅区冷热源型式的分析与比较

本文针对某住宅区设置集中式空调系统的要求,对风冷热泵冷热水机组、水冷螺杆式冷水机组＋燃油锅炉、由热电厂余热蒸汽驱动的蒸汽双效溴化锂吸收式冷水机组＋热交换器和燃气直燃型溴化锂吸收式冷温水机组等四种冷热源方案作了能耗和经济性比较,认为利用热电厂余热蒸汽为能耗的方案是最适合该住宅楼的空调方案。     

冷水机组运行特性建模与优化控制研究

为实现中央空调冷水机组运行优化,提出了基于支持向量回归机(SVR)建模的冷水机组优化控制方案。利用SVR建模思想,在冷水机组运行特性分析基础上,采用基于遗传算法的SVR参数优化算法,对冷水机组运行特性进行建模,并以此模型为基础提出了冷水机组运行参数寻优算法,通过动态调整机组运行参数实现节能。利用Matlab的Libsvm软件包对某螺杆式冷水机组运行特性进行建模,并在典型工况下,对优化控制方法和常规运行方法的能耗做了仿真对比。结果表明,采用基于SVR建模的冷水机组优化控制方法能显著提高冷水机组运行效率,具有很好的工程适应性和应用前景。     

制冷设备中进行能效比区域划分的初步探讨

提出了制冷设备能效比（EER）区域划分的概念,以上海、昆明为例,对比分析了两市空气源热泵空调器的实际使用能效比。结果表明：与现行能效比相比,对系统进行能效比区域划分,可相应地对制冷系统各部分进行优化,从而可以节省制造和运行成本,节能效果较为明显。同时,分析得出能效比区域划分,可以优化风冷冷水机组中综合部分负荷性能系数（IPLV）,使其具有较好的实用价值。     

Simulation analysis of factors influencing chiller EER

This study constructed a mathematic model of a variable frequency centrifugal chiller using Simulink software. By running the simulation, it was discovered that when the other factors are constant, the EER （Energy Efficiency Ratio） of the chiller increases with decreases in the temperature of the cooling water and increases in the tem- perature of the chilled water. The effect of changes in the cooling water temperature on the EER of the chiller is stronger than that of changes in the chilled water temperature. In addition, as the chiller load decreases, the EER increases until reaching a maximum, after which it decreases. Furthermore, the EER of chillers working under a constant flow rate is slightly higher than that of those working under varying flow rates.     

A simplified method to evaluate the seasonal energy performance of water chillers

The calculation or certification of the energy consumption of buildings equipped with refrigerating or heating units operating on vapour compression cycles requires an accurate evaluation of their performance at full and part load under different operating conditions. Refrigeration systems simulation models are normally useless because of the large amount of input data required for a full characterization.A simplified numerical method for the performance prediction of vapour compression heat pumps and chillers is here presented, based only on performance data at the nominal rating conditions. The proposed procedure was validated against experimental data of different packaged air-cooled water chillers, operating on scroll compressors. In chillers full load conditions approximately 89.5% and 92.1% of the predicted EER and cooling capacity values respectively are consistent with the measured data within a relative deviation of ±10%. Simulation results are in good agreement with the experimental ones also if the experimental seasonal energy efficiency ratio, SEER_on, described in the European standard draft prEN 14825, is considered. The deviations range from ?3.2% to +5.1%. The proposed mathematical model appears to be a reliable tool to be implemented into dynamic building-plant energy simulation codes or into building energy certification tools.     

Optimization of energy plants including water/lithium bromide absorption chillers

In this paper a methodology for the optimal integration of water/lithium bromide absorption chillers in combined heat and power plants is proposed. This method is based on the economic optimization of an energy plant that interacts with a refrigeration cycle, by using a successive linear programming technique (SLP). The aim of this paper is to study the viability of the integration of already technologically available absorption chillers in CHP plants. The results of this alternative are compared with the results obtained using the conventional way of producing chilled water, that is, using mechanical vapour compression chillers in order to select the best refrigeration cycle alternative for a given refrigeration demand. This approach is implemented in the computer program XV, and tested using the data obtained in the water/LiBr absorption chiller of Bayer in Tarragona (Catalonia, Spain). The results clearly show that absorption chillers are not only a good option when low‐cost process heat is available, but also when a cogeneration system is present. In this latter case, the absorption chiller acts as a bottoming cycle by using steam generated in the heat recovery boiler. In this way, the cogeneration size can be increased producing higher benefits than those obtained with the use of compression chillers. Copyright © 2000 John Wiley & Sons, Ltd.     

Chillers energy consumption, energy savings and emission analysis in an institutional buildings

Chillers consume more than 40% of the total energy used in the commercial and industrial buildings for space conditioning. In this paper, energy consumption by chillers and chilled water pumps, condenser pumps and fan motors has been estimated using data collected by a walkthrough energy audit for the 16 faculties of the University of Malaya. It has been estimated that chillers and motors and pumps used in chillers consume 10,737 MWh (i.e. 51% of total energy consumption) of electric energy for different percentage of loadings. As chillers are major energy users, variable speed drives are applied in chillers to reduce their energy consumption. It has been estimated that about 8368 MWh annual energy can be saved by using efficient chillers at different loadings. It has also been found that about 23,532 MWh annual energy can be saved for chilled water supply pumps, condenser pumps and cooling tower fan motors by matching required speeds using variable speed drives for 60% of speed reduction. About 1,274,692 kg of CO₂ emission could be avoided for using energy efficient chillers at 50% load. It has been also found that about 2,426,769 kg CO₂ emission can be reduced by using variable speed drives for 60% speed reductions. Payback periods found to be only few months for using variable speed drives in chilled water pumps, condensers and fan motors.     

Improved energy performance of air cooled centrifugal chillers with variable chilled water flow

This paper considers how to apply optimum condensing temperature control and variable chilled water flow to increase the coefficient of performance (COP) of air cooled centrifugal chillers. A thermodynamic model for the chillers was developed and validated using a wide range of operating data and specifications. The model considers real process phenomena, including capacity control by the inlet guide vanes of the compressor and an algorithm to determine the number and speed of condenser fans staged based on a set point of condensing temperature. Based on the validated model, it was found that optimizing the control of condensing temperature and varying the evaporator’s chilled water flow rate enable the COP to increase by 0.8–191.7%, depending on the load and ambient conditions. A cooling load profile of an office building in a subtropical climate was considered to assess the potential electricity savings resulting from the increased chiller COP and optimum staging of chillers and pumps. There is 16.3–21.0% reduction in the annual electricity consumption of the building’s chiller plant. The results of this paper provide useful information on how to implement a low energy chiller plant.     

Experimental investigation of the silica gel–water adsorption isotherm characteristics

In designing adsorption chillers that employs silica gel–water as adsorbent-adsorbate pair, the overriding objective is to exploit low temperature waste-heat sources from industry. This paper describes an experimental approach for the determination of thermodynamic characteristics of silica gel–water working pair that is essential for the sizing of adsorption chillers. The experiments incorporated the moisture balance technique, a control-volume-variable-pressure (CVVP) apparatus and three types of silica gel have been investigated, namely the Fuji Davison Type A, Type 3A and Type RD. As evidenced by the experimental results, the Henry-type equation is found to be suitable for describing the isotherm characteristics of silica gel–water working pair at the conditions of adsorption chiller. The regeneration of adsorbent depends on the correct allocation of temperature as well as the amount of regeneration time. From the experiments, the isotherm characteristics of silica gel–water in the low- to high-pressure regimes and hence, its isosteric heat of adsorption will be determined. Key parameters for optimizing the amount of heat recovery such as the cycle and switching time of chiller can also be implied from the measured results.     

Experimental investigation and performance analysis on a solar adsorption cooling system with/without heat storage

A solar adsorption cooling system which can be switched between a system with heat storage and a system without heat storage was designed. In the system with heat storage, a heat storage water tank was employed as the link between the solar collector circulation and the hot water circulation for the adsorption chillers. However, the heat storage water tank was isolated in the system without heat storage, and the hot water was directly circulated between the solar collector arrays and the adsorption chillers. It was found that the inlet and outlet temperatures for the solar collector arrays and the adsorption chillers in the system without heat storage were more fluctuant than those of the system with heat storage. Also found was that the system with heat storage operated stably because of the regulating effect by the heat storage water tank. However, under otherwise similar conditions, the cooling effect of the system without heat storage was similar to that of the system with heat storage. Compared with the system with heat storage, the system without heat storage has the advantages of higher solar collecting efficiency as well as higher electrical COP.