Research On The Change Law Of Hydraulic Regulation Of Centralized Heating Distributed Transmission And Distribution System

For a centralized heating distributed transmission and distribution system,when adding a heat exchange station or adjusting the flow of a branch circulating pump in a heat exchange station,hydraulic coupling will cause the redistribution of the flow of each branch of the system pipe network.In order to ensure the normal operation of the system and a good heating effect,it is very necessary to study the change law of the hydraulic regulation of the centralized heating distributed transmission and distribution system.The analysis of the hydraulic conditions of the central heating distributed transmission and distribution system is the basic task of studying the law of the system’s hydraulic regulation changes.As a centralized heating distributed transmission and distribution system with multiple circulating pumps operating in parallel,the working characteristics of the circulating pumps are the fundamental reason that affects the hydraulic working conditions of the system.In this paper,through the establishment of a centralized heating distributed transmission and distribution system simulation experiment platform,the flow rate change law of multiple circulating pumps of the same model and different models in parallel operation is analyzed and experimentally studied.The study finds that when the resistance characteristics of the pipe network change greatly,The flow rate of the circulating pump with a steeper characteristic curve changes little.Therefore,when running multiple circulating pumps in parallel,try to choose a circulating pump with a steeper characteristic curve,which is conducive to the hydraulic stability and operation adjustment of the system.This paper also conducts theoretical analysis and experimental simulation on hydraulic conditions such as adding heat exchange station circulating pumps,adjusting heat exchange station flow,and changing the resistance characteristics of the system’s pipe network in the central heating distributed transmission and distribution system.The study found that with the increase in the number of circulating pumps in the heat exchange station or the change in the resistance characteristics of the pipe network,the flow rate of the existing single circulating pump will change by 20%to 40%.When the circulating pump with larger flow or higher head is connected to the pipe network,it will have a greater impact on the flow of other circulating pumps.Especially when the circulating pump with higher head is connected to the pipe network,the flow rate of other pumps will be more affected.Therefore,the flow rate can be enriched by 20%to40%when the circulation pump of the pipe network of the central heating distribution system is selected,and the head should not be too rich.Try to choose a circulating pump with a steeper Q-H characteristic curve.In addition,the experimental analysis of the flow and resistance characteristics of the regulating valve that replaces the heat source,heat exchange station and the resistance of the heating network on the experimental bench of the centralized heating distributed transmission and distribution system is carried out.The flow coefficient K_Vand partial flow coefficient of the regulating valve on the system experimental bench are obtained.The fitting function and curve of the resistance coefficientξpave the way for the accurate theoretical hydraulic calculation and analysis of each operating state of the experimental platform.Through the above theoretical analysis and experimental simulation,this paper draws the law of system hydraulic conditions change under the conditions of multiple circulating pumps in parallel,heat source and pipe network circulating pumps increase,flow changes,and pipe network resistance characteristics changes.This law provides a reference for the study of the regulation change law of the hydraulic conditions of the central heating distributed transmission and distribution system,provides guidance and suggestions for the selection and operation adjustment of the circulating pump of the system,and also lays the foundation for the analysis of the thermal conditions of the system.