通断型末端冷水系统的多级变压差控制方法研究
Multi-stage variable pressure difference control method for on-off type terminal chilled water systems
摘要：
通断型末端冷水系统的变压差控制是变流量冷水系统的难点。为了解决通断控制阀位缺失对最不利热力环路辨识造成的影响,提出了根据末端温度矢量设定横管动态平衡阀压差的控制方法,并按串级控制原则,对立管动态压差平衡阀及干管的设定压差进行了逐级调整,以增强系统的控制稳定性。理论分析表明,该控制方法相比于干管定压差、末端定压差及变热力环路压差控制方法,具有供回水温差大、总流量及干管压差设定值更小的优势,用户侧冷水输送系数分别提升了47%～790%、36%～530%及34%～552%,显示了较大的节能潜力。
Abstract：
The variable pressure difference control in on-off type terminal chilled water systems is a difficult point of the variable flow chilled water systems. In order to solve the impact of the missing on-off control valve positions on the identification of the most unfavorable thermodynamic loops, a control method for setting the pressure difference of the dynamic balance valve of the crossbar according to the terminal temperature vector is proposed, and the set pressure difference of the dynamic differential pressure balance valve and the main pipe is adjusted step by step according to the principle of serial control to enhance the control stability of the system. Theoretical analysis shows that the control method has advantages of large temperature difference between supply and return water, smaller set value of total flow and main pipe pressure difference compared with the control methods of the main pipe constant pressure difference, the terminal constant pressure difference and the variable thermal loop pressure difference, and the chilled water transfer coefficient on the user side is increased by 47%-790%, 36%-530% and 34%-552%, respectively, showing greater energy-saving potential.
Keywords:variable flow chilled water system; variable pressure difference control; on-off type terminal; the most unfavorable thermal loop; chilled water transfer coefficient