中央空调系统变水温和变水量协调优化控制研究

通过水泵变频进行变水量调节是目前中央空调系统的主要节能手段,本文提出的基于变水温和变水量的协调优化控制策略可以取得更佳的节能效果。依据典型气象年数据,采用传递函数法,对典型房间的全年逐时空调负荷进行了计算;为了保证每个房间都能满足舒适性要求,以最不利负荷为优化计算的输入参数,根据部分负荷下表冷器的校核计算模型,在保证空调舒适性和设备安全运行的前提下,以系统能耗最低为目标函数,结合冷水机组、水泵和调节阀的变工况性能以及管路系统的水力特性,确定冷水机组的冷冻水出口温度及流量。对广州某综合大楼的实例计算表明,仅采用水泵变频,空调主机和水泵的总能耗降低17%,采用协调优化控制,则可降低22%;协调优化控制策略能够满足空调舒适性要求,且空调负荷越小,节能效果越明显,平均节能率最大值出现在12月,高达36.7%,最小值出现在7月,仅有14.5%。

Coordinated Control of Central Air-conditioning System based on Variable Chilled Water Temperature and Flowrate

At present,to regulate the water flowrate by adjusting the pump frequency is one of the major methods for energy-saving for central air-conditioning system.In this paper,coordinated control based on variable chilled water temperature and flowrate was used to obtain better energy-saving.Firstly,according to typical meteorological year data,hourly cooling load during the whole year for typical room had been calculated by transmission function method.Secondly,in order to guarantee the comfort level of each room,the highest cooling load value was used as an input parameter to optimize the calculation.Thirdly,based on the cooler check model,the smallest system energy consumption was taken as the objective function to guarantee the comfort level and the safety operation,the performance characteristics of chiller,water pump,regulation valve and pipeline were taken into account,and the optimization of chilled water temperature and flowrate were carried out.Fourthly,the case study of a commercial building in Guangzhou indicated that the annual energy consumption of the chillers and pumps was lowered by 17% with the pump frequency regulation,and reduced by 22% with coordinated control.As a result,the coordinated control could not only meet the comfort level,but also the lower the cooling load rate was,the more energy could be saved.In addition, the highest energy-saving rate of 36.7% occurred in December,and the lowest value of 14.5% occurred in July.