管网特性对水泵变流量运行能耗的影响

Influences of pipe network on energy consumption of variable flow pump

在暖通空调的水系统中,管网型式与阻力的变化对水泵运行特性产生重要的影响.通过实例对水泵变流量运行进行计算与分析,并采用管网阻力调节、水泵台数控制及变频控制方法调节系统流量.探讨了管网变化对水泵变流量运行能耗的影响;分析了管网性质与水泵运行工况的关系,以及各种流量调节方式与水泵运行能耗的关系.计算结果表明:管网特性对水泵变流量运行的能耗影响较大.通过增加管网的阻力调节流量,通常会使水泵的能耗降低;水泵变频控制方式对开、闭式管网的运行能耗影响有较大的区别,静压值越大,节能效果越小;在闭式循环管网中,水泵台数控制与变频控制是两种有效的节能调节方法,由于管网发生变化,水泵的运行工况变化不满足相似律;水系统通过采用压差控制流量时,最不利环路可能发生变化成为次不利环路,所以末端压差控制因管网变化而形成水力失调,最小阻力控制比定压差控制有显著的节能效果.

In the HVAC water systems,pipe network characteristics and impedances have important impacts on pump operation.Running example for the variable flow pump in different pipe network was calculated and analyzed through valve control,unit number control and frequency control.The influences of pipeline types on energy consumption of variable flow pump were discussed.The relationships between pipeline types and hydraulic operation characteristics of the pump,and that between flow control methods and energy consumption for pump operation were taken into account.The results show that pipe network characteristics have a great influence on energy consumption for a variable flow pump.Pump energy can be reduced by adjusting flow rate such as increasing the flow resistance of the pipeline.Under frequency control mode,energy consumption is decreased with increasing static pressure,energy consumption is also greater in closed pipe network than that in opened pipe network.In closed pipe network,pump number control and frequency control are two effective methods to adjust pump energy.The operation conditions do not meet the affinity laws due to the system changing.Within pressure difference control,the worst pressure differences of pipeline become the second adverse one probably.So pressure difference control could cause hydraulic misadjustment for variable end pipeline,the minimum resistance control has greater energy-saving than the constant pressure difference control.