集中式空调系统冷却水变流量特性研究

Research on variable cooling water flow characteristic of central air-conditioning system

冷却水流量的变化会对冷水机组、冷却水泵和冷却塔的运行性能产生不同程度的影响,冷却水变流量运行的节能效果一直存在争议。通过试验数据对比分析变频离心式冷水机组和变频螺杆式冷水机组在冷却水变流量下的运行特性,并通过仿真计算研究集中式空调系统在冷却水变流量下的节能特性。研究结果表明:当冷水机组负荷率在63%~100%范围内,冷却水流量减少对变频螺杆式冷水机组和变频离心式冷水机组的性能影响差别不大;当冷水机组负荷率小于63%时,变频离心式冷水机组性能衰减更大,而变频螺杆式冷水机组在低负荷下表现较好。在冷却塔风机定频运行条件下,当冷水机组负荷率在50%~100%范围内,冷却水变流量运行时集中式空调系统有较好的节能效果,其中,在负荷率70%~100%范围内,"变频离心式冷水机组+冷却水变流量"系统的节能效果优于"变频螺杆式冷水机组+冷却水变流量"系统;在负荷率50%~70%范围内,"变频螺杆式冷水机组+冷却水变流量"系统的节能效果较好。在冷却塔风机变频运行条件下,当冷水机组负荷率在60%~100%范围内,冷却水变流量运行时集中式空调系统有较好的节能效果,其中,在负荷率65%~100%范围内,"变频离心式冷水机组+冷却水变流量"系统的节能效果优于"变频螺杆式冷水机组+冷却水变流量"系统;在负荷率60%~65%范围内,"变频螺杆式冷水机组+冷却水变流量"系统的节能效果较好。

The variable cooling water flow has different influence on water chilling packages,cooling water pump and cooling tower,and the energy-saving effect of variable cooling water flow control is controversial.The operation performances of frequency-conversion centrifugal water chilling packages and frequency-conversion screw water chilling packages using variable cooling water flow control are analyzed contrastively by test data.In addition,the energy-saving characteristics of the central air-conditioning system using variable cooling water flow control are studied by simulation calculation.The research results show that when the part load ratio of water chilling packages is in the range of 63%-100%,the decrease of cooling water flow has little influence on the performance of frequency-conversion screw water chilling packages and frequency-conversion centrifugal water chilling packages;when the part load ratio of the water chilling packages is less than 63%,the performance attenuation of the frequency-conversion centrifugal water chilling packages is greater,while the performance of frequency-conversion screw water chilling packages is better under low load.Under the condition of the constant frequency of cooling tower fan,when the part load ratio is between 50%and 100%,the central air-conditioning system using variable cooling water flow control has better energy-saving effect.When the part load ratio is between 70%and 100%,the energy-saving effect of"frequency-conversion centrifugal water chilling packages+variable cooling water flow"system is better than that of"frequency-conversion screw water chilling packages+variable cooling water flow"system;when the part load ratio is between 50%and 70%,the energy-saving effect of"frequency-conversion screw water chilling packages+variable cooling water flow"system is better.Under the condition of frequency-conversion cooling tower fan,when the part load ratio is between 60%and 100%,the central air-conditioning system using variable cooling water flow control has better energy-saving effect.When the part load ratio is between 65%and 100%,the energy-saving effect of"frequency-conversion centrifugal water chilling packages+variable cooling water flow"system is better than that of"frequency-conversion screw water chilling packages+variable cooling water flow"system;when the part load ratio is between 60%and 65%,the energy-saving effect of"frequency-conversion screw water chilling packages+variable cooling water flow"system is better.