【作者】 陈涛；

【导师】 王海桥； 张登春；

【作者基本信息】 湖南科技大学 ， 供热、供燃气、通风及空调工程， 2008， 硕士

【摘要】 中央空调系统能耗在建筑能耗中占有很大比重,占建筑总能耗的65%左右。目前我国绝大多数中央空调水系统均为定流量系统,在运行过程中系统冷冻水流量不能跟随负荷变化,水泵始终按照设计负荷全速运行。然而空调系统在大部分时间都是在部分负荷下运行,因此会浪费大量水泵输送能源。近年来,随着国家对能源问题的重视和对节能工作的要求越来越高,作为目前最有效的节能措施之一,中央空调一次泵变流量系统的研究和应用逐渐受到人们的重视。本文阐述了一次泵变流量的一些基本理论和常用的检测控制系统,提出了一次泵变流量系统设计与应用的几个关键的技术问题。分析了冷冻水和冷却水变流量对冷水机组效率的影响,从而得出冷水机组的冷冻水和冷却水采用变流量是完全可行的,其综合节能效益显著。对一次泵变流量系统在不同控制方式下的水力工况进行了分析比较,探讨了变流量系统水力工况的稳定性,并用实例进行了验证,提出了系统水力失调的平衡措施。水泵的变频调速调节因有显著的节能效益,被认为是一次泵变流量系统最好的调节方式,但这种方式的节能效益与管路特性有着密切的关系。在考虑水泵效率、电机效率和变频器效率对水泵能耗的影响下,本文通过理论分析和实例计算,研究了变速节能效益与系统恒压值之间的关系。在水泵变频调节和变台数调节相结合的系统中,对于同一个目标流量,可以有多种组合方案,并且各种方案能耗是不相同的。本文以三台并联水泵为例,对水泵各种运行方案的能耗进行了比较分析,得出并联水泵的最佳(最低能耗)运行方案。所得结论对于优化变频水泵运行台数控制有一定的指导意义。最后结合工程实例,借助模拟软件DeST-c软件建立某建筑的能耗分析模型,模拟出该建筑的全年逐时动态负荷。根据所得的建筑逐时动态负荷,分别模拟了主机在几种不同的运行状态下的动态能耗。根据水泵运行时的最佳(最低能耗)运行方案,分别模拟了冷冻水泵在不同控制方式下的动态能耗,以及冷却水泵在变流量和定流量时的动态能耗。比较不同运行状态下的主机能耗、冷冻水泵能耗和冷却水泵能耗,得出中央空调系统采用不同控制方式的条件下一次泵变流量系统机房侧设备的总节能效益,为今后一次泵变流量系统设计作参考。更多还原

【Abstract】 The central air-conditioning system consumes high percent(about 65%)energy of building.Now the most building’s air-conditioning system is the constant flow system. They can not adjust chilled-water with the actual load of air conditioning,and the pumps always run with the constant speed.But in a majority of time the air-conditioning system work with parts of load.Therefore there would be a great deal of water the pump transport energy was wasted.In recent years,as energy problem become more important,and nation require further intensify energy-saving work.As one of the most effective energy-saving measures,we begin to pay more attention to the research and application of variable primary-flow system.In this paper the basic theories and detection and control system of variable primary flow system are expatiated first,and several key problems in variable primary-flow system’s design and application are proposed.The influence of variable flow rate of chilled water and cooling water on efficiency of the chiller’s efficiency is analyzed,and finds it is feasible and energy efficient to let chilled-water and cooling-water through the chiller to be variable.Next the hydraulic characteristics of different control modes in variable primary-flow system are analyzed and compared, the stability of hydraulic characteristics is discussed,it is verified by an example,and the equilibrium measures of hydrothermal are proposed.There are remarkable energy-saving benefits of variable frequency control of pump,and it is deemed to be the best in VWV system.But there is consanguineous relationship between the energy-saving benefit of pump and networks’ characteristics. Considering the influence of water pump efficiency,electric engine efficiency,the relations of the energy-saving benefits and the constant pressure are researched by theoretic analysis and calculation of an example.The combine of variable frequency and running number of the pumps,according to a goal flow,there are a few combined schemes,and their energy consumption is different.Using three parallel pumps,in this paper the energy consumption of various schemes of pumps is analyzed and compared,and the optimal(the lowest energy) combined scheme of pumps is educed.Its conclusion is instructional in optimizing the operational number of variable frequency pumps.In addition,combining with a project instance,in this paper a model of a building’s energy consumption through DeST-c of Tsing-Hua University,and the hourly dynamic air-conditioning load of this building is simulated.According to the hourly dynamic air-conditioning load,the dynamic energy consumption of chillers with different running states is simulated.According to the optimal(the lowest energy) combined scheme of parallel pumps,the dynamic energy consumption of chilled water pumps with different control modes,and dynamic energy consumption of cooling water pumps with variable water flow and constant water flow are simulated,the total energy-saving benefit in the plant of The central air-conditioning system which variable primary-flow system is adopted is educed by compared with the energy consumption of chillers,chilled water pumps and cooling water pumps which are operated in different states.In the end,the energy-saving benefit of variable primary-flow system in different outdoors weather parameters is researched,and its conclusion is instructional in design of variable primary-flow system.更多还原