闭式循环水系统的变频水泵能耗测试

Measure and Analyses of Pump Energy Consumein of Variable Frequency Water System

目的探讨影响闭式循环水系统水泵变频运行节能效果的原因及工程应用中循环水泵变频运行的控制范围.方法通过人工模拟空调负荷变化的方法对压力控制下的空调实验系统变频冷水泵的节能特性进行了实测分析.结果水泵有效功率和输入功率均随着电机频率的下降而不断降低,同时水泵效率也随着频率下降而降低.当电机频率由"效率突降点"40.82 Hz下降至39.74 Hz时,水泵效率iη从32.43%急剧下滑至23.05%.结论压力(差)控制下的变频水系统,在包含"效率突降点"的某一频段上水泵的运行效率具有急剧下滑的特性.处于或低于该频段时变频水泵往往不具备预估的节能效果.同时比例定律的直接套用也是导致变频水系统节能效果预估失真的原因.而高于"效率突降点"的频段时变频水系统具有明显的节能效果.

The aim of the study is to analyze the reasons that affect the energy-saving effect of variable frequency pump in closed circulating water system, and research the variable frequency range of circulating water pump in the engineering practice. Through simulating the change of air-conditioning load, the energy-saving characteristics of the variable-speed chilled water pump in air-condition experimental system were tested.The results show that available power and power input of water pump continuously decline with motor frequency reducing, and pump efficiency also decrease at the same time. Especially, pump efficiency suddenly glides from 34. 43 % to 23.05 % when motor frequency falls from ＂efficiency break point＂ 40. 82 Hz to 39.74 Hz. Based on the above analysis, under control of pressure difference, we can conclude that pump efficiency will suddenly glide in a frequency range including ＂efficiency break point＂. Variable-speed chilled water pump has an obvious energy-saving effect when motor frequency is higher than the frequency range; otherwise variable frequency pump perhaps has not the predicted energy-saving effect.