Study On The Regulation Characteristics Of Zero Pressure Difference Point-running In Central Heating System

In recent years,China's central heating industry has been rapidly developed.The scale of central heating is becoming large,and the new centralized heating system structure has been emerging.The distributed variable frequency central heating system is widely used in central heating system by virtue of its advantages of low energy consumption and high adjustment precision.In the distributed variable-frequency central heating system,the point that the pressure of water supply and backwater pressure is equal,that is zero pressure difference point.In this paper,the operating regulation characteristics of a distributed central heating system with zero pressure difference point are studied.First of all,with the zero pressure difference controlling point is located in the pipe network in a location of the actual central heating system as a simulation object,using the simulation software for the system to conduct the simulation of the operating conditions about variable zero pressure difference point regulation and constant zero pressure difference point adjustment.In variable zero pressure difference point condition,the hydraulic characteristics of the pipe network are analyzed when the varying flow rate is adjusted.In constant zero pressure difference point conditions,the hydraulic characteristics of two kinds of constant zero pressure differential pressure modes are analyzed and compared with the main circulating pump variable speed fixed zero pressure and pressure tube zero pressure difference pressure.Secondly,when zero pressure difference controlling point is in the heat source,using the uniform pressure pipe to fixe zero pressure difference point distributed system to simulate the analysis.The influence of the diameter and length of the uniform pressure pipe on the decoupling and the constant pressure capacity of the uniform pressure pipe was analyzed during the simulation.Simulation results based on rational design of uniform pressure pipe,the two kinds of different installation position system flow regulating hydraulic condition are simulated and analyzed in the heat source and the first heat user.The results show that compared with the variable zero pressure difference point regulation,the constant zero pressure difference point regulation mode has clear advantage in the flow stability,pressure stability,operability and pump energy consumption.The selection of the pipe diameter should be based on the flow adjustment amplitude of the pipenetwork,and the design principle of the diameter and length of the uniform pressure pipe is given.In the variable flow regulation,the uniform pressure pipe installed at the first hot user can improve the hydraulic stability of the distribution pump heat exchanger station,and weaken the coupling degree between the distribution pump heat transfer stations.The heating system is increasing in scale and the structure of the system is becoming more and more complicated.In this paper,the hydraulic characteristics of the central heating system with zero pressure difference are simulated and analyzed.The results provide a valuable reference for the operation and implementation of central heating system.