原文：
1 循环水泵容量过大的问题 循环水泵容量过大在我国是普遍存在的问题，其容量常常达到实际需要的2-4倍，造成工程投资和运行费用的严重浪费。其主要原因如下： 1.1 设计冷负荷偏大 设计冷负荷是选择设备的主要依据，所以正确地计算建筑冷负荷对整个空调系统的设计十分重要。目前，教科书及设计手册中提供的空调负荷计算方法不论是计算围护结构的墙壁负荷，还是门窗负荷，其计算结果都是针对某一具体房间而言。然而，空调系统设备容量是依据整个建筑的冷负荷确定。由于建筑内各房间的朝向、位置、使用功能及其发热源等因素的不同，往往造成各房间{zd0}冷负荷出现的时间并不相同。因此，建筑冷负荷的{zd0}值应为每个房间逐时负荷叠加的{zd0}值。据调查在我国有部分设计人员在计算建筑冷负荷时只是简单地将每个房间的{zd0}冷负荷进行叠加，导致计算结果远大于实际需求负荷。所以我们必须对此给予足够的重视，使设计负荷的确定更加合理正确。 1.2 系统循环阻力偏大 在计算系统循环阻力时，由于设计人员经验不足，使得一些计算参数取值过于保守，造成循环阻力计算值偏大，更有甚者，在施工图设计阶段采用估算方法确定循环阻力，致使计算循环阻力比实际值大一倍以上。 1.3 系统静压问题 空调系统充满水才能运行，水泵的进、出口承受相同的静水压力。因此，所选水泵的扬程只克服管道系统阻力即可。然而，有的设计者却把静水压力也计入该循环阻力之内，这当然会使循环水泵的容量增大很多。 1.4 系统水力平衡问题 由于设计时不认真进行系统的水力平衡计算，工程竣工后又未按要求进行全面调试，往往造成系统水力失调，系统出现冷热不均的现象。有些技术人员错误地认为造成此现象的原因是循环水泵的容量太小，结果只简单地采用加大水泵的方法解决了之，自然也就使水泵容量增大。 2 水泵特性曲线及{zj0}工作点 2.1 水泵的流量??扬程特性曲线 水泵的流量??扬程特性曲线一般有三种类型：平坦型、陡降型、驼峰型。用于空调水循环系统的水泵应具有平坦特性，其零流量与{zd0}流量之间的扬程变化范围不应大于10%-15%；陡降特性的水泵由于其{zd0}流量与最小流量间的扬程变化太大，故不宜选用；驼峰特性的水泵也不可采用，因为在两台水泵并联运行时可能引起负荷和扬程的周期变化，而当这一变化的频率等于系统的自振频率时便产生危险的“振荡现象”，而此现象将对系统的正常运行造成一定影响。 2.2 {zj0}工作点 循环水泵的{zj0}工作点是水泵特性曲线与系统管网特性曲线的交点A。但是，由于种种原因，系统的实际流量总是大于设计计算流量，其结果是设计水泵工作点沿水泵特性曲线向右偏移。 在水泵工作点向右偏移时，循环水泵所产生的扬程降低，这对系统的正常运行是极其不利的，尤其是系统中最不利环路，将促使该环路的流量进一步减少，影响正常使用功能。 　　造成工作点右移的原因主要有两个方面：首先是设计中水力计算采用过大的安全系数及不实际的压降计算方法，其次是设计的系统未进行认真的水力平衡计算，而施工后又未进行严格的系统调试。因此，为使系统按设计工况运行，除应认真仔细地进行相关计算外，还应在选择水泵时将水泵的工作点选择在{zj0}工作点左侧适当的位置，以防水泵实际工作点超出一定范围处于不经济的运行状况，影响系统正常运行。 3 循环水泵的技术经济分析 3.1 循环水泵的台数选择 《采暖通风与空气调节设计规范》（GBJ19-87，2001年版）第6.1.11条规定：冷水泵（一次泵）的台数及流量，应与制冷机的台数及设计工况下的流量相对应。二次泵的设置，应根据冷水系统的大小、各并联环路压力损失的差异程度、使用条件和调节要求等通过技术经济比较确定。然而在实际工作中，设计人员往往未对空调系统各种设备的综合配置进行全面的技术经济分析，结果造成工程初投资增加及“大马拉小车”等浪费资源的现象。为避免发生该现象，广大设计人员在方案设计阶段应依据使用功能、高低峰负荷时间、系统特征以及其它条件，针对空调系统中的冷水机组、循环泵、冷却塔等设备的综合配置进行全面充分的技术经济分析，以期在满足使用功能的前提下降低工程造价和运行费用。 3.2 工程寿命周期成本 笔者认为在进行循环水泵、冷水机组等设备的技术经济分析时应引入一个概念??工程寿命周期成本。工程寿命周期成本是工程设计、开发、建造、使用、维修和报废等过程发生的费用，也即该项目在其确定的寿命周期内或在预定的有效期内所需支付的设计费、建安费、运行维修费、报废回收费的总和。在不同项目和不同项目阶段寿命周期成本也大不相同。通常情况下，运营及维护成本往往大于项目建设的一次性投资。因此在进行技术经济分析时，应明确寿命周期成本包括的费用项目、各项费用的内容和范围以及它们在费用构成体系中的相互关系，这对我们进行技术经济比较十分重要。 3.3 价值工程 价值工程是以提高产品或作业价值为目的，通过>有组织的创造性工作寻求用{zd1}的寿命周期成 本可靠地实现使用者所需功能的一种管理技术，其表达式如式3.3.1。 V = F/C (3.3.1) 　　式中 V??研究对象的价值 　　　　 F??研究对象的功能 　　　　 C??研究对象的成本 此主题相关图片如下： 价值工程技术已广泛运用于研发、设计、建造等各行各业，其核心思想是以{zd1}的寿命周期成本使产品具备它所必须具备的功能。在空调设备选型及技术经济分析时，设计者应充分运用价值工程理念，力争以{zd1}工程投资达到必须的使用功能。当然就目前情况看，要达到这样的设计水平尚需时日，但广大设计人员应朝这个方向努力，以期取得良好的社会效益和经济效益。 4 结论 ① 在空调设计中应客观准确地计算冷负荷和系统阻力，避免因此而造成设备选型偏大； ② 选择循环水泵时，注意水泵工况点向右偏移现象，以保障水泵扬程变化在系统正常运行的允许范围之内； ③ 工程寿命周期成本和价值工程都是工程经济评价的良好工具，在做技术经济分析时应充分运用它们。

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译文：
1 The problem of excessive circulating pump capacity Circulating pump capacity overload is a common problem in our country, its capacity is often reached 2-4 times the actual needs, resulting in project investment and operating costs of a serious waste. The main reasons are: 1.1 The design cooling load is too large Design cooling load is the main basis for the selection of equipment, so proper cooling load calculation and design of the entire air conditioning system is very important. Currently, textbooks and design guide for the air conditioning load calculation method is to calculate the envelope regardless of the wall load, or load windows and doors, the results are speaking for a specific room. However, the air conditioning system equipment capacity is based on determining the building's cooling load. As the building toward the room, location, function and use of different heat sources and other factors, often result in the maximum cooling load of each room there is not the same time. Therefore, the maximum building cooling load for each room should be superimposed by the maximum value when the load. According to the survey, some designers in China in the calculation of building cooling load is simply the maximum cooling load of each room were superimposed, resulting in much higher than the actual demand load calculation. Therefore, we must pay enough attention to make the design more reasonable to determine the correct load. 1.2 system, vascular resistance is too large Vascular resistance in computing systems, due to lack of experience designers to make some calculations parameters are too conservative, resulting in vascular resistance calculated values are relatively large, even worse, in the construction design stage estimation method used to determine vascular resistance, resulting in calculation of circulation resistance than the actual value more than doubled. System static pressure of 1.3 issues Air-conditioning systems to run full of water, pump inlet and outlet bearing the same hydrostatic pressure. Therefore, the selected pump head can only overcome the resistance of pipeline systems. However, some designers have included confused hydrostatic pressure within the loop resistance, which of course will increase the capacity of many circulating pump. Hydraulic Balance 1.4 As the design of the hydraulic system is not seriously balance calculation, after completion of the project fails to require comprehensive debugging, often resulting in system hydraulic disorder system in the phenomenon of Enthusiasm. Some technical personnel mistakenly believe that this phenomenon is caused by circulating water pump capacity is too small, the results simply by increasing the pump means solved, naturally makes pump capacity increases. 2 pump characteristic curve and the optimum operating point 2.1 Pump flow - lift curve Pump flow - lift curves are generally three types: flat type, steep drop, humped. Water circulation pump for air conditioning systems should have the smooth features, the zero flow and maximum flow rate varies between the head should not exceed 10% -15%; steep drop characteristics of the pump because of its maximum flow and minimum flow rate changes between the head too, it should not be optional; hump pump characteristics can be used not because the two pumps running in parallel may cause periodic changes in load and lift, and when this change of frequency equal to the system natural frequencies have dangerous when they "oscillation", and this phenomenon will cause the normal operation of the system to some extent. 2.2 The optimal operating point Circulating pump is the best work with the system pump characteristic curve characteristic curve of the intersection of Pipeline A. However, for various reasons, the system is always greater than the design of the actual traffic flow is calculated, the result is the design of pump operating point along the pump curve to the right shift. Right shift in the pump operating point, the circulating pump generated head lower, this is the normal operation of the system is extremely detrimental, especially in the most unfavorable loop system, will lead to further reduce the flow of the loop, affecting the normal use function. Resulting operating point shifted to the right of the main reasons were twofold: first, the design of water calculated using the safety factor is too large and not practical in the pressure drop Fangfa, followed by a careful design of the system does not calculate the hydraulic Ping Heng, construction-Hou they did not conduct rigorous system debugging. Therefore, to make the system run according to the design conditions, in addition to the related detail should be carefully calculated, it should also select the pump in the pump's operating point will select the best operating point on the left in the appropriate position, the actual operating point to prevent water pump beyond a certain range of operating conditions is not the economy, affecting normal operation of the system. 3 Technical and Economic Analysis of Water Circulation Pump 3.1 Number of units circulating pump selection "Heating, ventilation and air conditioning design" (GBJ19-87, 2001 edition) Section 6.1.11 provides that: cold water pump (one pump) Number of units and flow, should be the number of refrigerator units and design of the flow condition corresponds to . Secondary pump settings, should be based on the size of the cooling water system, the difference in pressure loss parallel circuit level, using the conditions and adjust the requirements identified by technical and economic comparison. However, in practical work, designers are often not on the air conditioning system configuration of various equipment in the comprehensive technical and economic analysis, resulting in increased investment in construction works and the "big horse cart" and a waste of resources. To avoid this situation, the majority of designers in the design phase should be based on use function, the level of peak load time, the system features and other conditions for the air conditioning system, chillers, circulating pumps, cooling towers and other equipment to conduct a comprehensive fully integrated configuration Technical and economic analysis, in order to use functions to meet the premise of reducing project cost and operating costs. 3.2 The project life cycle costs I thought that in the circulating water pumps, chillers and other equipment, technical and economic analysis should be to introduce a concept - project life cycle cost. Project life cycle cost of engineering design, development, construction, use, maintenance and end of life process of the costs incurred, ie, its determination that the project life cycle or the life of the scheduled payment of design fees required, Jian Fei, Run maintenance costs, obsolescence charges back the sum. Projects and different projects in different stages of life cycle costs vary greatly. Typically, operating and maintenance costs are often greater than the construction of one-time investment. Therefore, when carrying out technical and economic analysis, life cycle costs should be explicitly included in the cost of the project, the cost of the content and scope and their fee structure system of mutual relations which is very important to our technical and economic comparison. 3.3 Value Engineering Value Engineering is to enhance the value of products or operations for the purpose of seeking creative work through organized with the lowest life cycle cost and reliable to achieve the required functionality of a user management technology, its expression, such as type 3.3.1. V = F / C (3.3.1) Type in the V - the value of study F - the function of the object C - cost of study Picture this topic are as follows: Value engineering has been widely used in research and development, design, construction and other industries, its core idea is the lowest life cycle costs make the products with which it must have features. Selection in the air-conditioning and techno-economic analysis, the designer should make full use of value engineering concepts, and strive to achieve the minimum project investment must be the use function. Of course, the present situation, to achieve such a design level will take time but the majority of designers should move in this direction in order to achieve good social and economic benefits. 4 Conclusion ① In the air conditioning design should be objectively and accurately calculate the cooling load and system resistance, resulting in equipment selection to avoid too large; ② Select circulating pump, the pump operating point to the right attention to the phenomenon of migration, changes to protect the pump head to allow normal operation of the system within the scope; ③ project life cycle cost and value engineering are good tools for economic evaluation in the technical and economic analysis should be done to fully use them.